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A THESISSUBMITTED TO THE
SAURASHTRA UNIVERSITYFOR THE DEGREE OF
Doctor of PhilosophyIN
THE FACULTY OF SCIENCE ( CHEMSITRY )
BY
KIRITKUMAR P. VAISHNANI
UNDER THE GUIDANCE
OF
Dr. SHIPRA BALUJADr. SHIPRA BALUJADr. SHIPRA BALUJADr. SHIPRA BALUJADr. SHIPRA BALUJA
Department of ChemistrySaurashtra University
Rajkot- 360 005Gujarat - (INDIA)
2006
Doctor of Philosophy
Gram : UNIVERSITY Phone : (R) 2584221 Fax : 0281-2577633 (O) 2578512
SAURASHTRA UNIVERSITYUniversity Road. Rajkot - 360 005.
Dr. Shipra Baluja Residence : M.Sc., Ph.D. 20A/2-Saurashtra University Associate Professor Karmachari Society Department of Chemistry University Road,
Rajkot - 360 005. GUJARAT (INDIA)
No.
Statement under O.Ph.D. 7 of Saurashtra University
The work included in the thesis is my own work under the
supervision of Dr. Shipra Baluja and leads to some contribution in chemistry subsidised
by a nnumber of references.
Dt. : 27 - 02 - 2006 ( KIRITKUMAR P. VAISHNANI )
Place : Rajkot.
This is to certify that the present work submitted for the Ph. D. Degree
University by Kiritkumar P. Vaishnani is his own work and leads to advancement in the
knowledge of chemistry.
The thesis has been prepared under my supervision.
Date : 27 - 02 - 2006 Dr. SHIPRA BALUJA Place : Rajkot. Associate Professor
Department of Chemistry, Saurashtra University Rajkot - 360 005.
ACKNOWLEDGEMENT
Completing of my research work is truly a marathon event and I would not
have been able to complete this journey without the co-operation and support of
countless people over the past three years. I can not find the word to express the
deepest gratitude to my esteemed teacher, adorable guide DR. SHIPRA BALUJA,
Associate Professor, Department of Chemistry, Saurashtra University, Rajkot. Her
invaluable guidance, constructive criticism, motivative attitude, punctuality,
encouragement, tremendous help, parental care and expert supervision throughout
the research work brought my efforts to fruition.
I extend deep sense of gratitude to Prof. H. H. Parekh, Head, Department of
Chemistry, Saurashtra University, Rajkot, for providing necessary facilities and
administrative help.
With a deep sense of gratitude I wish to express my sincere thanks to
Prof. P. H. Parsania, Dr. A. K. Shah, Dr. V. H. Shah, and Shree Hareshbhai
Kundal for their moral support and encouragement.
I would like to extend my thanks to non- teaching staff of Chemistry
Department. Special thanks to Mr. Pankaj Kachhadia for Mass and IR data.
I specially thank Dr. U. V. Manvar, Ex. Dean of Science Faculty,
Saurashtra University, Rajkot, for Stimulating suggestions and encouragement.
I express my sincere thanks to my principal, Shree M. M. Raval, Dean of
Science Faculty, Saurashtra University, Rajkot, Shree J. P. Dholakia, Head,
Department of Chemistry and my all staff members of Bahauddin Science College,
Junagadh, for kind support and providing facilities.
I also consider myself very fortunate to have been provided with invaluable
help and moral support by Shree S. G. Desai, Joint Director, Higher Education,
Gandhinagar.
I wish to express my gratitude to Prof. S. V. Chanda, Department of
Bioscience, Saurashtra University, Rajkot and Dr. Nimish Mungara, P. D. U.
Medical College Rajkot, for the help in conducting biological activities.
I find myself in difficult position to express my deep indebtedness to my
colleagues and friends, Dr. K. M. Rajkotia, Dr. Joshi, Shree G. K. Bera, Dr. D. C.
Karia, Dr. Pranav, Dr. Mayur, Dr. Anjana, Asif, Nikunj, Nirmal, P. K. Kasundra,
J. C. Javia, N. V. Gothi, Dr. Harshad, Sangani, Dr. Vaghela, Nilesh, Janak, Sunil,
Niral, Rahul, Harshad, Bhavin, Dushyant, Bhardavabhai, Chavdabhai, Vazabhai
and Jitendra.
I am thankful to Dr. Narendra V. Patel, Mr. Vipul Chatrabhuji and
Dr. Parimal Chatrabhuji for motivating and giving moral support.
I shall remain indebted to my Parents and Family Members for their
affection and moral support. I get emotional when I think about the sacrifice of my
Wife Rekha and Children during my busy hours.
I express my Sincere thanks to Mr. Rajubhai Solanki for his Excellent Type
Setting and timely completion of these documents.
And finally, still there are many more Well-Wishers, Friends, Relatives, who
directly and indirectly rendered me valuable help and moral strength to complete this
academic endeavour. I have deep reverence for all of them.
Last but not the least, I praise and thank Lord Krishna, Whose benevolent blessing
always keep me on the right track.
Following organization made my task easier due to extension of their facilities :
Director, CDIR - Lucknow. ( Mass and NMR )
R. S. I. C. Nagpur University – Nagpur. ( TGA/ DTA )
R. S. I. C. Punjab University – Chandigarh. ( NMR )
Department of Chemistry, S. P. University,V.V.Nagar. ( DSC )
Department of Chemistry, Saurashtra University, Rajkot. ( Mass and IR )
Department of Bioscience, Saurashtra University, Rajkot. ( Biological
Activities )
P. D. U. Medical College Rajkot. ( Biological Activities )
KIRITKUMAR P. VAISHNANI
CONTENTS
SYNOPSIS PAGE
No.
CHAPTER - I LITERATURE SURVEY ON SYNTHESIS, CHARACTERIZATION AND APPLICATIONS OF SCHIFF BASES AND THIAZOLIDINONES
1-15
CHAPTER - II SYNTHESIS OF SCHIFF BASES AND THIAZOLIDINONES
16-24
CHAPTER - III SPECTRAL CHARACTERIZATION 25- 119
CHAPTER - IV DETERMINATION OF PHYSICOCHEMICAL PROPERTIES
SECTION – 1 HEAT OF SOLUTION 120-125
SECTION - 2 DENSITY 126-140
SECTION - 3 CONDUCTANCE 141-156
SECTION - 4 DISSOCIATION CONSTANTS 157-184
SECTION - 5 ACOUSTICAL PROPERTIES 185-215
SECTION - 6 THERMAL PROPERTIES 216-244
CHAPTER - V BIOLOGICAL ACTIVITIES 245-254
CHAPTER - VI A COMPREHENSIVE SUMMARY OF THE WORK
255-257
LIST OF PAPERS COMMUNICATED 258
0
CHAPTER - I
LITERATURE SURVEY
ON SYNTHESIS, CHARACTERIZATION
AND APPLICATIONS OF SCHIFF
BASES
AND THIAZOLIDINONES
1
Introduction :
The importance and uses of physicochemical properties are well
recognized. The applications and implications of compounds in certain
systems can be decided only if their physico chemical properties are known.
The major differences among behavioral profiles of molecules in the
environment are attributable to their physicochemical properties. For most
chemicals, only fragmentary knowledge exists about those properties that
determine the application of a compound. A chemical-by-chemical
measurement of the required properties is not practical because of expense.
Further, trained technicians and adequate facilities are not available for
measurement efforts involving thousands of chemicals. In fact, physical and
chemical properties have only actually been measured for about 1 percent of
the approximately 70,000 industrial chemicals. Hence, the need for physical
and chemical constants of chemical compounds has greatly accelerated in
industries, which are always in search of economical and better chemicals.
Although considerable progress has been made in process elucidation
and modeling for chemical processes[1-5], such as photolysis and hydrolysis,
only for a limited number of compounds reliable estimates of the related
fundamental thermodynamic and physicochemical properties (i.e.,
rate/equilibrium constants, distribution coefficient, solubility in water, etc.)
have been achieved. The values of these latter parameters, in most
instances, must be derived from measurements or from the expert judgment
of specialists in that particular area of chemistry. Nowadays, computer
programs are also available to estimate a variety of reactivity parameters[6-14].
This capability crosses chemical family boundaries to cover a broad range of
organic compounds.
The majority of the reactions occurring in solutions are of chemical or
biological in nature. It was previously presumed that solvent only provides an
inert medium for chemical reactions. The significance of solute-solvent
interactions was realized only recently as a result of extensive studied in
aqueous, non aqueous and mixed solvents. Ion-solvent and ion-ion
interactions play a major role in determining the behavior of solutes in
2
solutions[15-18]. In recent years, there has been an increasing interest in the
behavior of solutes in non-aqueous and mixed solvents with a view to
investigating ion-ion and ion-solvent interactions under varied conditions[19].
Fundamental research on non-aqueous electrolyte solutions has
catalyzed their wide technical applications in many fields. Non-aqueous
electrolyte solutions are competing with other ion conductors, especially at
ambient and at low temperatures, due to their high flexibility based on the
choice of numerous solvents, additives and electrolytes with widely varying
properties. However, different sequence of solubility, difference in solvating
power and possibilities of chemical or electrochemical reactions unfamiliar in
aqueous chemistry have open vistas for physical chemists and interest in
these organic solvents transcends the traditional boundaries of inorganic,
organic, analytical and physical chemistry.
The proper understanding of the interactions in solutions would form
the basis of explaining quantitatively the influence of the solvent and the
extent of interactions of ions in solvents and thus pave the way for real
understanding of different phenomena associated with solution chemistry.
These interactions in solutions can be interpreted by conductance, density,
viscosity, and acoustical data. The changes in ionic solvation have important
applications in organic and inorganic synthesis, study of reaction
mechanisms, non aqueous battery technology and extraction.
The density, specific volume, molecular mass and refractive index are
useful in the evaluation of various thermodynamic properties of chemical
materials. The values of heat of solution of different solutes in different
solvents are very much useful in industries. Further, solubilities and Henry's
Law constants[20-26] are also important properties for the application of various
compounds.
Knowledge of the acid-base ionization properties of organic molecules
is essential to describing their environmental transport and transformations, or
estimating their potential environmental effects. For ionizable compounds,
solubility, partitioning phenomena and chemical reactivity are all highly
dependent on the state of ionization in any condensed phase. The ionization
3
pKa of an organic compound is a vital piece of information in environmental
exposure assessment. It can be used to define the degree of ionization and
resulting propensity for sorption to soil and sediment that, in turn, can
determine a compound’s mobility, reaction kinetics, bioavailability,
complexation, etc[27].
The measurement of any property of a specimen undergoing a
programmed temperature change is thermal analysis. Thermal analysis
delivers information often unobtainable by other means. It has been used in
many areas of basic and applied research, quality control and acceptance,
prediction and performance evaluation of products. The thermal analysis
kinetic parameters are applied to problems such as failure and service life
prediction, oxidative stability, thermal breakdown, quality assurance and
control, and also optimizing conditions during industrial synthesis and
fabrication[28].
In the present work, the physico chemical properties such as density,
conductance, heat of solution, dissociations constants, thermal kinetics,
acoustical properties etc. of some organic compounds have been studied.
Among the various types of organic compounds, Schiff bases and
Thiazolidinones have been selected for the present study. The selection of
these compounds is due to their applications in various fields.
Day by Day, Schiff bases are known to be applied for human welfare.
Many Schiff bases are known to be useful in perfumery[29], as corrosion
inhibitor[30], as complexing agents(31) and as intermediate in many
reactions[32-35]. Some other applications of Schiff bases have also been
reported in literature in various fields[36-39]. Further, many workers[40-46]
reported a wide range of biological activities of various Schiff bases.
Literature survey shows that various workers synthesized[47-54] Schiff
bases due to their vivid applications. The preparation of some Schiff bases
have been reported by Sawodny et al[55]. Vazquoz et al[56] reported synthesis
of some Schiff bases from glycine and pyridoxal-5’-phosphate, pyridoxal and
5’-deoxy pyridoxal. Tietze synthesized some Schiff bases from 3-acetyl
tetramic acids with ethylene diamine[57]. Synthesis of some tripodal Schiff
4
bases have also been reported[58]. The characterization of synthesized Schiff
bases has been reported to be done by elemental analysis, IR, NMR and
mass spectral data [59-68]. Dash et al studied mass spectra of Schiff bases
derived from p-hydroxy benzaldehyde and their derivatives[69]. Khuhawar et al
studied infrared spectra of some Schiff base polymers derivatives[70]. NMR
study of Schiff bases from 2-hydroxy-1-naphthaldehyde was reported by
Schiff et al[71]. Przybylski et al reported mass spectra of some Schiff bases
from 5-hydroxy-3-oxapentylamine[72].
Various properties of Schiff bases have been reported[73-81]. Mishra and
Gautam[82] reported acoustical properties of some Schiff bases and their
complexes. Siddique et al[83]. also studied ultrasonic properties of some Schiff
bases in CCl4-water, ethanol-water and acetone-water mixtures. Sarkar et al
also studied thermal properties of some Schiff bases [84]. Chantarasiri et al
also reported some physico-chemical properties of hexadentate Schiff base
derived from salicylaldehydes and triethylenetetramine and zinc complexes[85].
Thiazolidinones, which belong to an important group of hetrocyclic
compounds have been extensively explored for their applications. The
thiazolidinones, substituted at 2 and 3 position are reported to exhibit a wide
variety of biological activities such as antibacterial[86,87], antitubercular[88], anti
HIV and anticancer[89], antidiabetic[90], insecticidal[91], herbicidal[92]
anthelmintics[93], cardiovascular[94], antiviral[95], hypnotic[96-98], antifungal[99-101],
antitumor[102], antiulcer[103], local anaesthetic[104] and antimicrobial[105,106].
Due to various biological activities of these compounds, various
workers[107-117] have synthesized thiazolidinones. Several methods for the
preparation of 4-thiazolidinones are nararated in literature [118-124]. Shah and
Trivedi[125] have synthesized thiazolidinones from 4-aryl thiosemicarbazones
by condensing them with chloroacetic acid, a-bromopropionic and a-
bromophenyl acetic acid. Nath and coworkers[126] have prepared 4-
thiazolidinones by cyclization of N-aryl-N’-(2'-pyridyl)-thiocarbamide with
chloroacetic acid. Saeda et al[127]. have synthesized some new
thiazolidinones.
5
Recently, various workers studied their biological properties[128-136].
Lodhi and co-workers[137] have been synthesized and studied antimicrobial,
antiinflammatory and analgesic property of 4-thiazolidinone and arylidene
derivatives. Mogilaiah and co-workers[138] isolated some 4-thiazolidinone
derivatives and tested their antibacterial activity Bhawana et al[139] have
synthesized thiazolidinone derivatives and compared their antiinflammatory
activity, ulcerogenic liability, cardiovascular and CNS effects. Sun et al
elucidated structure-antioxidant activity relationship for some thiazolidinones
derivatives[140]. Kocabalkanli et al also evaluated antimicrobial activities of
some 2, 5-disubstituted -4-thiazolidinones[141]. Kucukguzel et al[142] have
synthesized thiazolidinones as antimicrobial and anticancer agent. Tonghui et
al[143] have documented thiazolidinones as CFTR (cystic fibrosis
transmembrane conductance regulator) inhibitor. Sonawane et al[144] have
also synthesized some new thiaolidinone derivatives as in vivo pharmacology
and studied antidiarrheal efficacy of a thiazolidinone CFTR inhibitor in
rodents. CFTR inhibition of some new thiazolidinones have also been
reported[145,146]. Recently, Dayam et al.(147) have reported some novel
thiazolidinone derivatives as novel class of HIV- integrase inhibitors.
Küçükgüzel et al(148) also reported synthesis and biological activity of some 4-
thiazolidinones.
These valid observations led us to explore the synthesis and physico
chemical properties of some Schiff bases and thiazolidinones.
6
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16
The following Schiff bases have been synthesized from p-amino
phenol.
1 KPV-1 2-[(4-hydroxyphenyl)imino]methyl phenol
2 KPV-2 4-[(2-chlorophenyl)methylene]aminophenol
3 KPV-3 4-[(4-methoxyphenyl)methylene]aminophenol
4 KPV-4 4-[(2-nitrophenyl)methylene]amino phenol
5 KPV-5 4-[(3-nitrophenyl)methylene]aminophenol
6 KPV-6 4-[2-furylmethylene]aminophenol
7 KPV-7 4-[(4-chlorophenyl)methylene]aminophenol
8 KPV-8 4-[(4-hydroxyphenyl)imino]methyl-2-methoxyphenol
17
Synthesis of Schiff bases from p-amino phenol :
The requisite amount of aldehyde, dissolved in 20 ml methanol was
added to 0.1 mole of p-aminophenol and few drops of glacial acetic acid,
which acts as a catalyst. The mixture was refluxed for 10-12 hours at 70-80oC
in water bath.
The resulting solution was cooled to room temperature, and then
poured in crushed ice with constant stirring. The precipitate was filtered and
washed with Sodium bisulfite solution to remove excess of aldehyde. The
product was crystallized from hot methanol and dried.
R-CHO +
N
OH
CH RNH2
OH
where R =
OH Cl
KPV - 1
KPV - 4
OCH3
KPV - 7
NO2
KPV - 3
NO2
OH
OCH3
KPV - 5
KPV - 8
Cl
O
KPV - 2
KPV - 6
18
The physical constants of the synthesized Schiff bases are reported in Table
2.1.
Table 2.1 : Physical constants of KPV Schiff bases.
Compound Code
Molecular Formula
Molecular
Weight g
M.P. OC
% Yield
Rf* Value
KPV-1 C13 H11 N O2 213.235 140 58.7 0.64*
KPV-2 C13 H10 Cl N O 231.678 122 62.5 0.58*
KPV-3 C14 H13 N O2 227.259 165 67.8 0.44+
KPV-4 C13 H10 N2 O3 242.230 166 60.5 0.61*
KPV-5 C13 H10 N2 O3 242.230 162 66.7 0.65*
KPV-6 C11 H9 N O2 187.195 214 54.3 0.62#
KPV-7 C13 H10 Cl N O 231.678 210 53.6 0.44+
KPV-8 C14 H13 N O3 243.258 182 61.4 0.64+
* Ethyl acetate : Benzene - 2.0 : 8.0
+ Acetone : Benzene - 1.0 : 9.0
# Acetone : Benzene - 0.3 : 9.7
19
The following Schiff bases have been synthesized from p-fluoro
aniline.
1 RKV- 1 2-[(4-fluorophenyl)imino]methylphenol
2 RKV- 2 4-[(4-fluorophenyl)imino]methylphenol
3 RKV- 3 4-fluoro-n-[-(2-nitrophenyl)methylene]aniline
4 RKV- 4 N-[-(2-chlorophenyl)methylene]-4-fluoroaniline
5 RKV- 5 N-[-(4-chlorophenyl)methylene]-4-fluoroaniline
6 RKV- 6 4-[(4-fluorophenyl)imino]methyl-n,n-dimethyl-aniline
7 RKV- 7 4-fluoro-n-[-(4-methoxyphenyl)methylene]aniline
8 RKV- 8 4-[(4-fluorophenyl)imino]methyl-2-methoxyphenol
20
Synthesis of Schiff bases from p-fluoro aniline :
The requisite amount of aldehyde, dissolved in 20 ml methanol was
added to 0.1 mole of p-fluoro aniline and few drops of glacial acetic acid,
which acts as a catalyst. The mixture was refluxed for 10-12 hours at 70-80oC
in water bath.
The resulting solution was cooled to room temperature, and then
poured in crushed ice with constant stirring. The precipitate was filtered and
washed with Sodium bisulfite solution to remove excess of aldehyde. The
product was crystallized from hot methanol and dried.
R-CHO +
N
F
CH RNH2
F
Where R =
OH
Cl
RKV - 1
OCH3
NO2
RKV - 3
OH
OCH3
RKV - 5
RKV - 8
Cl
OH
NH3C CH3
RKV - 2
RKV - 6RKV - 4
RKV - 7
21
The physical constants of the synthesized Schiff bases are reported in Table
2.2.
Table 2.2 : Physical constants of RKV Schiff bases.
Compound Code
Molecular Formula
Molecular
Weight g
M.P. OC
% Yield
Rf* Value
RKV-1 C13 H10F N O 215.22 64 71.2 0.52 *
RKV-2 C13 H10F N O 215.22 164 58.5 0.61 *
RKV-3 C13 H9 N2 O2 244.22 63 65.8 0.59#
RKV-4 C13 H9ClFN 233.67 54 42.3 0.63*
RKV-5 C13 H9ClFN 233.67 60 57.5 0.49*
RKV-6 C15H15FN2 242.29 71 65.2 0.58#
RKV-7 C14H12FN O 229.25 52 59.6 0.62#
RKV-8 C14 H12FN O2 245.25 93 62.0 0.51#
* Acetone : Benzene - 1.0 : 9.0
# Acetone : Benzene - 1.5 : 8.5
22
The following Thiazolidinones have been synthesized from Schiff
bases of p-fluoro aniline.
1 DKV-1 2-(2-hydroxyphenyl)-3-(4-methylphenyl)-1,3-thiazolidin-4-one
2 DKV-2 2-(4-hydroxyphenyl)-3-(4-methylphenyl)-1,3-thiazolidin- 4-one
3 DKV-3 3-(4-methylphenyl)-2-(2-nitrophenyl)-1,3-thiazolidin-4-one
4 DKV-4 2-(2-chlorophenyl)-3-(4-methylphenyl)-1,3-thiazolidin-4-one
5 DKV-5 2-(4-chlorophenyl)-3-(4-methylphenyl)-1,3-thiazolidin- 4-one
23
Synthesis of Thiazolidinones :
The requisite amount of Schiff base dissolved in 20 ml methanol, was
added to 0.1 mole of thio glycolic acid and few drops of glacial acetic acid.
The mixture was refluxed for 10-12 hours at 70-80oC in water bath.
The resulting solution was cooled to room temperature, and then
poured in crushed ice with constant stirring. The precipitate was filtered and
washed with water. The product was crystallized from hot methanol and dried.
R-CH=N-R' + HSCH2COOHN
S
O R
R'
where R’ =
F
and R =
OH
DKV - 2
OH
DKV - 1
NO2
Cl
Cl
DKV - 3
DKV - 4 DKV - 5
24
The physical constants of the synthesized Thiazolidinones are reported in
Table 2.3.
Table 2.3: Physical constants of Thiazolidinones.
Compound Code
Molecular Formula
Molecular
Weight g
M.P. OC
% Yield
Rf* Value
DKV-1 C15 H12F N O2S 289.33 56 70.2 0.53
DKV-2 C15 H12F N O2S 289.33 102 67.8 0.62
DKV-3 C15 H11F N2 O3S 318.32 70 56.3 0.56
DKV-4 C15 H11Cl FNOS 307.77 81 32.5 0.63
DKV-5 C15 H11Cl FNOS 307.77 90 45.0 0.48
* Acetone: Benzene - 1.0: 9.0
25
Spectral studies of Schiff bases and Thiazolidinones :
The compounds are well characterized on the basis of infrared (IR), nuclear
magnetic resonance (NMR) and mass spectral data.
Infra-Red Spectra :
Infra-Red spectroscopy is one of the powerful analytical techniques which
offer the possibility of chemical identification.
IR spectrum arises due to excitation of vibrational and rotational energy
levels of the molecular or individual functional groups. It is also called as
“Vibrational Spectroscopy”. IR spectroscopy is an excellent method for the
qualitative analysis because except optical isomers, the spectrum of compound
is unique. It is most useful for the identification of purity and gross structural
details. This method is also useful in the field of natural products, forensic
chemistry and in industrial analysis of competitive products, determination of
force constant, bond strength, identification of compounds, presence of certain
groups in the molecules, identification of hydrogen bonding, study of co-ordination
compounds, polymers and detection of impurity etc.
25 The IR spectra (KBr pellets) of Schiff bases scanned on SHIMADZU
– FT -IR-8400 over the frequency range from 4000-400 cm-1 are shown in Figure
3.1 to 3.21. The characteristic absorption frequencies in cm-1 are given along with
the spectra.
26
0.0
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cmsb salicyaldehyde
455.2
497.6 543.9
617.2 698.2
721.3
748.3
829.3
906.5 941.2
968.2
1045.31122.5
1172.61234.4
1276.8
1377.11442.7
1508.2
1593.1
1612.4
2923.93008.7
3066.63097.5
FIG. 3.1 : IR SPECTRAL STUDY OF 2-[(4- HYDROXYPHENYL)IMINO] METHYL PHENOL (KPV-1)
NOH
OH
Type
Vibration mode
Frequency in cm-1
Expected frequency in cm-1 (1-3)
-OH
-O-H (sym.) O-H ( asym.)
3398 1377
3400 - 3200 1410 - 1310
Aromatic -C=C (str.) 1593 1600 - 1585 C-C ( o. o. p. d. ) 698 710 - 675 -C-H ( i. p. d. ) 1045 1300 - 1000
Ar-N=C-Ar -N=C(str.) 1612 1640 - 1580
27
O H
N
H O
T y p e
V i b r a t i o n m o d e
F r e q u e n c y i n c m - 1
E x p e c t e d f r e q u e n c y
i n c m - 1 (1 - 3 )
- O -H ( s y m . ) 3 3 9 8 - O H
O - H ( a s y m . ) 1 3 6 1 3 4 0 0 - 3 2 0 0 1 4 1 0 - 1 3 0 0
A r o m a t i c - C=C ( s t r . ) 1 5 0 4 1 6 0 0 - 1 4 5 0 C - C ( o . o . p . d . ) 7 5 6 7 1 0 - 6 7 5 - C -H ( i . p . d . ) 1 1 1 1 1 3 0 0 - 1 0 0 0
A r- N = C - A r - N=C(s t r . ) 1 6 1 6 1 6 4 0-1 5 8 0 C -C l - C - C l (str .) 7 5 6 7 6 0 -7 0 0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cmsb o-choloro
455.2
520.7
563.2
636.5
756.0
810.0
837.0
906.5 972.1
1026.11110.9
1157.2
1184.21215.1
1253.6
1361.7
1450.4
1504.4
1616.2
2923.92958.6
3398.3
FIG. 3.2 : IR SPECTRAL STUDY OF 4-[(2-CHLOROPHENYL) METHYLENE]AMINOPHENOL (KPV-2)
NOH
Cl
28
30.0
40.0
50.0
60.0
70.0
80.0
90.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cmsb p-och3
432.0
505.3 528.5
543.9 617.2
721.3
756.0
829.3
894.9 937.3
979.8
1022.21103.2
1168.8
1226.6
1265.2
1365.5
1438.8
1515.9
1569.9
1608.5
2565.1
2927.73089.8
FIG. 3.3 : IR SPECTRAL STUDY OF 4-[(4-METHOXY PHENYL) METHYLENE]AMINOPHENOL ( KPV-3)
OH
N
HO
Type
Vibration mode
Frequency incm-1
Expected frequency incm-1 (1-3)
-O-H (sym.) 3300 -OH
O-H ( asym.) 1365 3400-3200 1410-1300
Alkane -C-H (def.) sym. 2927 2975-2915 Aromatic -C=C (str.) 1569 1600-1585
C-C ( o. o. p. d. ) 756 710-675 -C-H ( i. p. d. ) 1265 1300-1000
Ar-N=C-Ar -N=C(str.) 1608 1640-1580 -C-O-C (str.) 1022 1070-1000
NOH
OCH3
29
FIG. 3.4 : IR SPECTRAL STUDY OF 4-[(2-NITROPHENYL)METHYLENE] AMINOPHENOL (KPV-4)
HO N
O2N
T y p e
V i b r a t i o n m o d e
F r e q u e n c y i n c m - 1
E x p e c t e d f r e q u e n c y
i n c m - 1 ( 1 -3 )
-O H O -H ( asym.) 1 3 4 0 1 4 1 0 -1 3 0 0
Aromat ic -C=C ( s t r . ) 1 5 8 9 1 6 0 0 -1 5 8 5
C -C ( o . o . p . d . ) 694 7 1 0 -675
-C - H ( i . p . d. ) 1 2 7 1 1 3 0 0 -1 0 0 0
A r -N=C -A r -N=C(s t r . ) 161 0 1640 -1580
N O 2 -C - N O 2 (sym.) 1 2 4 2 1390 -1250
-C -N O 2 ( asym.) 1 5 0 8 1 5 9 0 -1 5 0 0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0%T
500.0750.01000.01250.01500.01750.02000.03250.01/cm2-no2
424.3
468.7
505.3 540.0
624.9
673.1
694.3
738.7 794.6
831.3
1105.11141.8
1164.9
1242.1
1271.01340.4
1452.31508.2
1589.21610.4
2335.62482.2
2601.8
30
FIG. 3.5 : IR SPECTRAL STUDY 4-[(3-NITROPHENYL)METHYLENE]AMINO PHENOL (KPV-5)
NOH
NO2
OH
N
HO
Type Vibration mode
Frequency incm-1
Expected frequency
incm-1 (1-3) -O-H (sym.) 3250
-OH O-H ( asym.) 1273 3400-3200 1410-1300
Aromatic -C=C (str.) 1581 1600-1585 C-C ( o. o. p. d. ) 671 710-675 -C-H ( i. p. d. ) 1103 1300-1000
Ar-N=C-Ar -N=C(str.) 1620 1640-1580 -C-NO2 (sym.) 1510 1590-1500
NO2 -C-NO2 ( asym.) 1350 1390-1250
0.0
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cm3-no2
420.5
482.2 540.0
671.2
715.5
734.8 792.7
835.1
877.6 896.8
929.6 954.7
977.81082.0
1103.21163.0
1230.51272.9
1313.4
1350.11444.61581.5
1620.1
1886.3
2337.6
2459.1
2590.22669.3
31
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0%T
500.0750.01000.01250.01500.01750.02000.03250.01/cmfarfuraldehyde
466.7 528.5
594.0 671.2
736.8 829.3
960.5
1018.31103.2
1164.9
1234.4
1365.5
1454.21508.2
1604.7
2923.9
3240.2
FIG. 3.6 : IR SPECTRAL STUDY OF 4-[2-FURYLMETHYLENE]AMINO PHENOL (KPV-6)
NOHO
OH
N
HO
Type
Vibration mode
Frequency incm-1
Expected frequency
incm-1 (1-3) -O-H (sym.) 3240
-OH O-H ( asym.) 1366 3400-3200 1410-1300
Aromatic -C=C (str.) 1604 1600-1585 C-C ( o. o. p. d. ) 671 710-675 -C-H ( i. p. d. ) 1103 1300-1000
Ar-N=C-Ar -N=C(str.) 1605 1640-1580 -C-O-C (str.) 1018 1070-1000
32
FIG. 3.7 : IR SPECTRAL STUDY OF 4-[(4-CHOLOROPHENYL)METHYLENE] AMINOPHENOL (KPV-7)
NOH
Cl
OH
N
HO
Type Vibration mode
Frequency incm-1
Expected frequency
incm-1 (1-3) -O-H (sym.) 3210 -OH
O-H ( asym.) 1350 3400-3200 1410-1300
Aromatic -C=C (str.) 1595 1600-1450 C-C ( o. o. p. d. ) 719 710-675 -C-H ( i. p. d. ) 1107 1300-1000
Ar-N=C-Ar -N=C(str.) 1620 1640-1580 C-Cl -C- Cl (str.) 760 760-700
0.0
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cm4-chloro
410.8
491.8
513.0
549.7
624.9
684.7 719.4
759.9
823.5
889.1
941.2
975.9
1010.6
1083.91107.1
1163.01226.6
1274.9
1350.1
1446.5
1504.41595.0
1620.1
2337.6
33
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cmvaniline
462.9 516.9 644.2
821.6
1026.1
1122.51164.9
1265.2
1369.4
1454.21512.1
1596.9
2067.5
2846.7
2931.6
3232.5
FIG. 3.8 : IR SPECTRAL STUDY OF 4-[(4-HYDROXY PHENYL)IMINO]METHYL -2-METHOXYPHENOL (KPV-8)
NOH
OH
OCH3
O H
N
H O
Type Vibration mode
Frequency incm -1
Expected frequency
incm -1 (1 -3)
-O H O -H ( sym.) 3233 3400-3200 O -H ( asym.) 1369 1410-1300
Alkane -C-H (def . ) sym. 2847 2880-2860 -C H 3 -C-H (def.) asym. 2932 2975-2915
Aromatic -C=C (str.) 1596 1 60 0-1585 C-C ( o. o. p. d. ) 644 710-675 -C-H ( i. p. d. ) 1026 1300-1000
A r-N=C -A r -N=C(str .) 1596 1640-1580 -C-O -C (str.) 1026 1070-1000
34
FIG. 3.9 : 2-[(4-FLUOROPHENYL)IMINO]METHYLPHENOL (RKV-1)
NF
OH
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cm4-fl aniline+salisaldehyde
419.5
484.1
519.8
738.7
755.1
767.6
793.7
812.0
838.0
908.4 957.6
1031.81099.3
1149.5
1181.3
1230.51272.0
1299.9
1359.71385.8
1458.11489.9
1504.4
1542.0
1560.3
1570.9
1593.1
1615.3
2359.73418.6
OH
N
HO
Type Vibration mode
Frequency incm-1
Expected frequency
incm -1 (1-3) -O-H (sym.) 3418 -OH
O-H ( asym.) 1359 3400-3200 1410-1300
Aromatic -C=C (str.) 1593 1600-1450 C-C ( o. o. p. d. ) 738 710-675 -C-H ( i. p. d. ) 1272 1300-1000
Ar-N=C-Ar -N=C(str.) 1615 1640-1580 C-F -C- F (str.) 1385 1400-1000
35
FIG. 3.10 : 4-[(4-FLUOROPHENYL)IMINO]METHYLPHENOL (RKV-2)
NF
OH
0.0
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cm4-fl aniline+ 4-oh ald
429.1
461.0 498.6 541.0
582.5
634.5 710.7
762.8
889.1 967.2
1007.71098.4
1350.1
1384.81556.41614.3
2328.9
OH
N
HO
Type Vibration mode
Frequency incm-1
Expected frequency
incm-1 (1-3) Aromatic -C=C (str.) 1556 1600-1450
C-C ( o. o. p. d. ) 693 710-675 -C-H ( i. p. d. ) 1260 1300-1000
Ar-N=C-Ar -N=C(str.) 1614 1640-1580 C-F C-F(str.) 1346 1400-1000 NO2 -C-NO2 (sym.) 1311 1390-1250
-C-NO2 ( asym.) 1572 1590-1500
36
FIG. 3.11 : 4-FLUORO-N-[-(2-NITROPHENYL)METHYLENE]ANILINE (RKV-3)
0.0
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cm4-fl aniline+ 2- nitro ald
415.6
476.4 509.2
539.1
677.9
693.4 711.7
738.7 775.3
812.9
828.4
896.8 967.2
1099.31138.9
1159.1
1187.11216.0
1274.9
1311.5
1346.2
1443.61572.8
1591.2
1627.8
3047.3
OH
N
HO
Type Vibration mode
Frequency incm -1
Expected frequency
incm -1 (1-3) Aromatic -C=C (str.) 1589 1600-1450
C -C ( o. o. p. d. ) 720 710-675 -C-H ( i. p. d. ) 1218 1300-1000
A r-N=C -A r -N=C(str.) 1628 1640-1580 C-F C -F(str.) 1366 1400-1000 NO 2 -C-N O2(sym.) 1346 1390-1250
-C-NO 2(asym.) 1573 1590-1500
NF
O2N
37
FIG. 3.12 : N-[-(2-CHLOROPHENYL)METHYLENE]-4-FLUOROANILINE (RKV-4)
NF
Cl
0.0
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cm4-fl aniline+ O-cl ald
426.2
455.2 488.9 502.4
545.8
619.1
696.3
720.4
760.9 779.2
833.2
887.2 968.2
1009.7
1030.91051.1
1094.5
1121.5
1151.4
1163.0
1186.1
1218.01272.0
1293.2
1366.5
1436.91466.8
1499.6
1567.1
1589.21616.2
2918.13413.8
OH
N
HO
Type Vibration mode
Frequency incm-1
Expected frequency
incm-1 (1-3) Aromatic -C=C (str.) 1589 1600-1585
C-C ( o. o. p. d. ) 720 710-675 -C-H ( i. p. d. ) 1218 1300-1000
Ar-N=C-Ar -N=C(str.) 1616 1640-1580 C-Cl -C- Cl (str.) 760 750-700 C-F C-F(str.) 1366 1400-1000
38
FIG. 3.13 : N-[-(4-CHLOROPHENYL)METHYLENE]-4-FLUOROANILINE (RKV-5)
NF
Cl
0.0
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cm4-fl aniline+ p- cl ald
414.7
476.4
516.9
542.9
680.8 705.9
718.4 774.4
804.3 825.5
887.2
947.0 973.0
1010.6
1083.0
1153.41166.9
1188.11215.1
1352.01405.0
1471.6
1502.4
1542.0
1567.1
1590.21624.9
1908.4
2360.7
2876.6
3427.3
OH
N
HO
Type Vibration mode
Frequency incm-1
Expected frequency
incm-1 (1-3) Aromatic -C=C (str.) 1590 1600-1585
C-C ( o. o. p. d. ) 705 710-675 -C-H ( i. p. d. ) 1215 1300-1000
Ar-N=C-Ar -N=C(str.) 1624 1640-1580 C-Cl -C- Cl (str.) 718 750-700 C-F C-F(str.) 1352 1400-1000
39
FIG. 3.14 : 4-[(4-FLUOROPHENYL)IMINO]METHYL-N,N-DIMETHYL- ANILINE (RKV-6)
NF
N
CH3
CH3
0.0
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cm4-fl aniline+ n,n- di methyl ald poured
470.6
492.8
540.0
727.1
778.2
800.4
818.7
839.0
944.1 974.9
1066.6
1094.51123.5
1164.01216.0
1257.51293.2
1315.4
1365.5
1414.7
1429.2
1498.6
1530.4
1582.51604.7
2814.9
OH
N
H O
T y p e V i b r a t i o n m o d e
Frequency incm - 1
E x p e c t e d f r e q u e n c y
incm - 1 (1 -3 ) A l k a n e -C -H (str.) (sym.) 2 8 1 4 2 8 8 0 -2 8 6 0
-C -H(st r . ) (asym.) 2 9 6 0 2 9 7 5 -2 9 5 0 -N -( C H3 )2 1 3 6 5 1 3 8 5 -1 3 7 0
Aroma t i c -C = C - (str.) 1 5 8 3 1 6 0 0 -1 5 8 5 C -C ( o. o. p. d. ) 7 2 7 7 1 0 -6 7 5 -C -H ( i . p . d . ) 1 1 6 4 1 3 0 0 -1 0 0 0
A r-N = C - A r -N=C(s t r . ) 1 6 0 4 1 6 4 0 -1 5 8 0 C -F C -F(str .) 1 2 1 6 1 4 0 0 -1 0 0 0
40
FIG. 3.15 : 4-FLUORO-N-[-(4-METHOXYPHENYL)METHYLENE] ANILINE (RKV-7)
0.0
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cm4-fl aniline+ p- anisaldehyde
420.5
435.9
487.0 512.1
542.9
580.5
725.2
748.3
787.9 810.0
840.9
886.2 974.0
1022.2
1096.51107.1
1160.1
1179.4
1209.31253.6
1279.7
1308.6
1360.7
1421.4
1440.7
1461.01498.6
1571.91603.7
1625.9
2845.83431.1
O H
N
H O
T y p e V i b r a t i o n m o d e
F r e q u e n c y i n c m - 1
E x p e c t e d f r e q u e n c y
i n c m -1 ( 1 -3 )
A l k a n e -C -H ( s t r . ) ( s y m . ) 2 9 7 0 2 9 7 5 - 2 9 5 0 -C -H ( s t r . ) ( a s y m . ) 2 8 4 5 2 8 8 0 - 2 8 6 0 C -H ( b e n d ) 1 4 4 0 1 4 7 0 - 1 4 3 5
A r o m a t i c -C = C -( s t r . ) 1 6 0 3 1 6 0 0 - 1 5 8 5 C -C ( o . o . p . d . ) 7 2 5 7 1 0 - 6 7 5 -C -H ( i . p . d . ) 1 2 5 3 1 3 0 0 - 1 0 0 0
A r-N = C -A r -N = C ( s t r . ) 1 6 2 5 1 6 4 0- 1 5 8 0 C -F C -F ( s t r . ) 1 3 6 0 1 4 0 0 - 1 0 0 0
C -O -C C -O -C ( s t r . ) 1 0 2 2 1 0 7 0 - 1 0 0 0
NF
OCH3
41
FIG. 3.16 : 4-[(4-FLUOROPHENYL)IMINO]METHYL-2-METHOXYPHENOL (RKV-8)
NF
OH
OCH3
0.0
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cm4-fl aniline+ vaniline
422.4
463.8 483.1 510.1
526.5
591.1
617.2
650.9
708.8
758.0
781.1
835.1
870.8 931.6
974.0
1028.01045.3
1092.6
1122.51159.11283.5
1380.0
1428.2
1463.9
1513.11593.1
1624.9
2848.7
2945.1
O H
N
H O
T y p e V i b r a t i o n m o d e
F r e q u e n c y i n c m - 1
E x p e c t e d f r e q u e n c y
i n c m -1
- O - H - O - H ( s y m . ) 3 3 0 0 3 4 0 0 - 3 2 0 0 - O - H ( a s y m . ) 1 3 8 0 1 4 1 0 - 1 3 0 0
A l k a n e - C - H ( s t r . ) ( s y m . ) 2 8 4 9 2 8 8 0 - 2 8 6 0 - C - H ( s t r . ) ( a s y m . ) 2 9 4 5 2 9 7 5 - 2 9 5 0
A r o m a t i c - C = C - ( s tr . ) 1 5 9 3 1 6 0 0 - 1 5 8 5 C - C ( o . o . p . d . ) 7 0 8 7 1 0 - 6 7 5 - C - H ( i . p . d . ) 1 2 8 3 1 3 0 0 - 1 0 0 0
A r - N = C - A r - N = C ( s t r . ) 1 6 2 4 1 6 4 0 - 1 5 8 0 C - F C - F ( s t r . ) 1 1 5 9 1 4 0 0 - 1 0 0 0
C - O - C C - O - C ( s t r . ) 1 0 4 5 1 0 7 0 - 1 0 0 0
42
FIG. 3.17 : 2-(2-HYDROXYPHENYL)-3-(4-METHYLPHENYL)-1,3-THIAZOLIDIN- 4-ONE (DKV-1)
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cmthio salisaldehyde
419.5
484.1
519.8
738.7
755.1
767.6
793.7
812.0
838.0
908.4 957.6
1031.81099.3
1149.5
1181.3
1230.51272.0
1299.91360.7
1458.11489.9
1504.4
1542.9
1593.1
1615.3
2852.5
2923.9
O H
N
H O
T y p e V i b r a t i o n m o d e
F r e q u e n c y i n c m -1
E x p e c t e d f r e q u e n c y
i n c m -1 ( 1 -3 )
-O -H - O -H ( s y m . ) 3 3 4 0 3 4 0 0 -3 2 0 0 - O - H ( a s y m . ) 1 3 6 0 1 4 1 0 -1 3 0 0
A r o m a t i c - C = C -(str . ) 1 5 9 3 1 6 0 0 -1 5 8 5 C -C ( o . o . p . d . ) 7 3 8 7 1 0 -6 7 5 - C - H ( i . p . d. ) 1 2 7 2 1 3 0 0 -1 0 0 0
C = O - C = O (str.) 1 7 0 0 1 7 0 0 -1 8 5 0 C -S C -S (str . ) 5 1 9 7 0 0 -5 7 0
C -N C -N ( v i b .) 8 3 8 9 2 0 -8 3 0 C -F C -F (str . ) 1 0 3 2 1 0 7 0 -1 0 0 0
F
N
S
O
OH
43
FIG. 3.18 : 2-(4-HYDROXYPHENYL)-3-(4-METHYLPHENYL)-1,3-THIAZOLIDIN- 4-ONE (DKV-2)
F
N
S
O OH
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cm4-oh+thio
430.1
462.9 497.6
538.1 761.8
794.6
833.2
979.8
1103.2
1163.0
1188.1
1238.21286.4
1346.2
1388.7
1444.61502.4
1575.71598.9
1668.3
2327.9
2480.32590.2
3361.7
O H
N
H O
T y p e V i b r a t i o n m o d e
F r e q u e n c y i n c m -1
E x p e c t e d f r e q u e n c y
i n c m -1 (1 -3 )
-O -H - O - H ( s y m . ) 3 3 6 1 3 4 0 0 -3 2 0 0 - O - H ( a s y m . ) 1 3 8 8 1 4 1 0 -1 3 0 0
A r o m a t i c - C = C -(str . ) 1 5 9 8 1 6 0 0 -1 5 8 5 C -C ( o . o . p . d . ) 6 9 0 7 1 0 -6 7 5 - C - H ( i . p . d. ) 1 2 3 8 1 3 0 0 -1 0 0 0
C = O - C = O (str.) 1 6 6 8 1 7 0 0 -1 8 5 0 C -S C -S (str . ) 6 8 0 7 0 0 -5 7 0 C -N C -N ( v i b .) 8 3 3 9 2 0 -8 3 0 C -F C -F (str . ) 1 1 0 3 1 0 7 0 -1 0 0 0
44
FIG. 3.19: 3-(4-METHYLPHENYL)-2-(2-NITROPHENYL)-1,3-THIAZOLIDIN- 4-ONE (DKV-3)
F
N
S
O
O 2N
0.0
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cmthio 2-no2
419.5
495.7
528.5 602.7
728.1
777.3
788.8
823.5
836.1
866.9
1133.11157.2
1219.91232.4
1301.9
1321.11349.1
1380.0
1449.4
1509.2
1604.7
1692.4
1869.82344.3
2852.5
2923.9
O H
N
H O
T y p e V i b r a t i o n m o d e
F r e q u e n c y i n c m -1
E x p e c t e d f r e q u e n c y
incm -1 (1 -3 )
A r o m a t i c - C = C -(str . ) 1 6 0 4 1 6 0 0 -1 5 8 5 C -C ( o . o . p . d . ) 7 2 8 7 1 0 -6 7 5 - C - H ( i . p . d . ) 1 2 3 2 1 3 0 0 -1 0 0 0
A r- N O 2 ( C - N O 2) ( sym.) 1 3 8 0 1 3 9 0 -1 2 5 0 ( C - N O 2) ( asym.) 1 5 0 9 1 5 9 0 -1 5 0 0
C = O C = O (str.) 1 6 9 2 1 8 5 0 -1 7 0 0 C -S C - S (str.) 6 0 2 7 0 0 -5 7 0 C -N C -N (vib . ) 8 3 6 9 2 0 -8 3 0 C -F C -F (str . ) 1 0 0 0 1 0 7 0 -1 0 0 0
45
FIG. 3.20: 2-(2-CHLOROPHENYL)-3-(4-METHYLPHENYL)-1,3-THIAZOLIDIN- 4-ONE (DKV-4)
F
N
S
O
Cl
0.0
20.0
40.0
60.0
80.0
100.0
%T
500.0750.01000.01250.01500.01750.02000.03250.01/cmthio o-cl
417.6 455.2
497.6
527.5
600.8 619.1
690.5
703.0
750.3
777.3
822.6
836.1
896.81015.5
1042.5
1096.51145.61156.2
1218.0
1234.4
1299.9
1320.21380.0
1449.41469.7
1509.2
1603.7
1692.4
2852.5
2924.8
O H
N
HO
Type Vibrat ion mode
Frequency incm -1
Expected frequency
incm -1 (1 -3 )
Aromatic -C=C-(str.) 1603 1600-1585 C-C ( o. o. p. d. ) 703 710-675 -C -H ( i. p. d. ) 1234 1300-1000
C =O C=O (str.) 1692 1850-1700 C-S C -S (str.) 600 700-570 C -N C-N (vib.) 836 920-830 C -C l C-Cltr.) 690 700-550 C-F C-F (str.) 1015 1070-1000
46
FIG. 3.21 : 2-(4-CHLOROPHENYL)-3-(4-METHYLPHENYL)-1,3-THIAZOLIDIN- 4-ONE (DKV-5)
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0%T
500.0750.01000.01250.01500.01750.02000.03250.01/cmp-cl thio
432.0
493.7
580.5
613.3
761.8
815.8 835.1
1012.6
1087.8
1126.4
1159.11180.4
1213.1
1292.2
1334.6
1380.9
1413.7
1460.0
1508.2
1596.9
1681.8
3068.53446.6
O H
N
HO
Type Vibration mode
Frequency incm -1
Expected frequency
incm -1 (1 -3 )
Aromatic -C=C-(str.) 1596 1600-1585 C -C ( o. o. p. d. ) 680 710-675 -C -H ( i. p. d. ) 1213 1300-1000
C =O C = O (str.) 1681 1850-1700 C-S C -S (str.) 613 700-570 C -N C -N (vib.) 835 920-830 C -C l C -Cltr.) 580 700-550 C-F C -F (str.) 1012 1070-1000
F
N
S
O Cl
47
1H NMR Spectral data :
The study of radio frequency radiation by nuclear is called Nuclear Magnetic
Resonance (NMR).
1H NMR is one of the most powerful tools available to the chemists and
biochemists for elucidating the structure of chemical species.At a given radio
frequency, all protons in a molecule may give NMR at different applied field
strengths.
In the presence of an externally applied magnetic field, a spinning nucleus
can only assume a limited number of stable orientations. In a magnetic field, a
spinning nucleus in lower energetic orientation absorbs sufficient electromagnetic
radiation and is excited to a higher energetic orientation. This results in nuclear
magnetic resonance.
1H NMR spectrum gives valuable data about the carbon chain, structural
diagnosis, conformational analysis, determination of reaction velocities, keto-
enol tautomerism, to study exchange effects, in determination of activation energy,
decoupling experiments identify the neighboring groups of protons, paramagnetic
shift reagents simplify complex spectra, the adjacent groups of protons and also
the number of groups of equivalent protons and hence of the nature of atoms in
the chain, the integration give the number of protons in each group of equivalent
protons.
The NMR spectra were scanned on Burker 300 KHz by using deuterated
chloroform or dimethyl sulfoxide as a solvent.
The chemical shift (δ ppm), and multiplicities of some Schiff bases are
reported in Tables 3.1 to 3.14 along with their spectra. ( Figures: 3.22 to 3.35)
48
FIG
. 3.2
2 :
NM
R S
PE
CT
RA
OF
2-[
(4- H
YD
RO
XY
PH
EN
YL
) IM
INO
] ME
TH
YL
P
HE
NO
L (K
PV
-1)
49
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
1 6.90 -8.23 8 H Multiple Ar - H 2 8.93 2 H Singlet = C - H
NOH
OH
TABLE 3.1 : NMR SPECTRAL STUDY OF 2-[(4- HYDROXYPHENYL) IMINO] METHYL PHENOL (KPV-1)
50
FIG
. 3.2
3 : N
MR
SP
EC
TR
A O
F 4
-[(
2-C
HL
OR
OP
HE
NY
L)
ME
TH
YL
EN
E]A
MIN
OP
HE
NO
L (
KP
V-2
)
51
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
a 6.86 -7.42 8 H Multiple Ar - H b 13.51 1 H Singlet O - H c 8.65 1 H Singlet = C - H
TABLE 3.2 : NMR SPECTRAL STUDY OF 4-[(2-CHLOROPHENYL) METHYLENE]AMINOPHENOL (KPV-2)
NOH
Cl
52
FIG
. 3.2
4 : N
MR
SP
EC
TR
A O
F 4
-[(
4-M
ET
HO
XY
PH
EN
YL
)ME
TH
YL
EN
E]A
MIN
OP
HE
NO
L (
KP
V-3)
53
TABLE 3.3 : NMR SPECTRAL STUDY OF 4-[(4-METHOXYPHENYL) METHYLENE]AMINOPHENOL ( KPV-3)
NOH
OCH3
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
a 6.83 -7.86 8 H Multiple Ar - H b 3.66 1 H Singlet O - H c 8.39 1 H Singlet = C - H d 3.89 3 H Singlet -OCH3
54
FIG
. 3.2
5 : N
MR
SP
EC
TR
A O
F 4
-[(
2-N
ITR
OP
HE
NY
L)M
ET
HY
LE
NE
]AM
INO
PH
EN
OL
(K
PV
-4)
55
TABLE 3.4 : NMR SPECTRAL STUDY OF 4-[(2-NITROPHENYL) METHYLENE]AMINOPHENOL (KPV-4)
HO N
O2N
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
a 6.89 -8.29 8 H Multiple Ar - H b 3.24 1 H Singlet O - H c 8.9 1 H Singlet = C - H
56
FIG
. 3.2
6 : N
MR
SP
EC
TR
A O
F 4
-[(
3-N
ITR
OP
HE
NY
L)M
ET
HY
LE
NE
]AM
INO
P
HE
NO
L (
KP
V-5
)
57
TABLE 3.5 : NMR SPECTRAL STUDY OF 4-[(3-NITROPHENYL) METHYLENE]AMINO PHENOL (KPV-5)
NOH
NO2
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
a 6.87 -8.58 8 H Multiple Ar - H b 9.09 1 H Singlet O - H c 8.71 1 H Singlet = C - H
59
TABLE 3.6 : NMR SPECTRAL STUDY OF 4-[2-FURYLMETHYLENE]AMINO PHENOL (KPV-6)
NOHO
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
a 6.55 -7.44 4 H Multiple Ar - H
b 7.85 - 8.25 3 H Multiple - H (furaran) c 8.87 1 H Singlet = C - H
60
FIG
. 3.2
8 :
NM
R S
PE
CT
RA
OF
4-
[(4-
CH
OL
OR
OP
HE
NY
L)M
ET
HY
LE
NE
]AM
INO
PH
EN
OL
(K
PV
-7)
61
TABLE 3.7 : NMR SPECTRAL STUDY OF 4-[(4-CHOLOROPHENYL) METHYLENE]AMINOPHENOL (KPV-7)
NOH
Cl
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
a 6.84 -7.83 8 H Multiple Ar - H b 9.03 1 H Singlet O - H c 8.45 1 H Singlet = C - H
62
FIG
. 3.2
9 : N
MR
SP
EC
TR
A O
F 4
-[(
4-H
YD
RO
XY
PH
EN
YL
)IM
INO
]ME
TH
YL
-2-
ME
TH
OX
YP
HE
NO
L (K
PV
-8)
63
TABLE 3.8 : NMR SPECTRAL STUDY OF 4-[(4-HYDROXY PHENYL) IMINO]METHYL-2-METHOXYPHENOL (KPV-8)
NOH
OH
OCH3
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
a 6.81 -7.62 7H Multiple Ar - H b 8.35 1 H Singlet = C - H c 8.95 1 H Singlet - O- H d 3.94 3H Singlet -OCH3
64
FI
G. 3
.30
: NM
R S
PE
CT
RA
OF
2-[
(4-F
LU
OR
OP
HE
NY
L) I
MIN
O]M
ET
HY
LP
HE
NO
L (
RK
V-1
)
65
TABLE 3.9 : NMR SPECTRAL STUDY OF 2-[(4-FLUOROPHENYL) IMINO]METHYLPHENOL (RKV-1)
NF
OH
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
a 6.91 -7.14 4 H Multiple Ar -OH
b 7.23 - 7.41 4 H Multiple Ar -F c 13.10 1 H Singlet -OH
d 8.59 1 H Singlet -N=CH
66
FIG
. 3.3
1 : N
MR
SP
EC
TRA
OF
4-FL
UO
RO
-N-(2
-NIT
RO
PH
EN
YL)
ME
THY
LEN
E]A
NIL
INE
(RK
V-3
)
67
TABLE 3.10 : NMR SPECTRAL STUDY OF 4-FLUORO-N-(2-NITROPHENYL) METHYLENE]ANILINE (RKV-3 )
NF
O2N
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
a 7.08 – 7.74 4 H Multiple Ar – NO2 b 8.06 – 8.31 4 H Singlet Ar - F c 8.93 1 H Singlet -N= C H
68
FIG
. 3.3
2 : N
MR
SP
EC
TR
A O
F N
-[-(
2-C
HL
OR
OP
HE
NY
L)
ME
TH
YL
EN
E]-
4-F
LU
OR
OA
NIL
INE
(R
KV-
4)
69
TABLE 3.11 : NMR SPECTRAL STUDY OF N-[-(2-CHLOROPHENYL) METHYLENE]-4-FLUOROANILINE (RKV-4)
NF
Cl
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
a 7.06 – 7.26 4 H Multiple Ar - F
b 7.35 – 8.24 4 H Singlet Ar – Cl c 8.90 1 H Singlet -N= C H
70
FIG
. 3.3
3 : N
MR
SP
EC
TR
A 2
-(2-
HY
DR
OX
YP
HE
NY
L)-3
-(4-
ME
THY
LPH
EN
YL)
-1,3
-TH
IAZO
LID
IN- 4
-ON
E (D
KV
-1)
71
TABLE 3.12 : NMR SPECTRAL STUDY OF 2-(2-HYDROXYPHENYL)-3- (4-METHYLPHENYL)-1,3-THIAZOLIDIN- 4-ONE (DKV-1)
F
N
S
O
OH
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
a 6.91 -7.14 4 H Multiple Ar - F b 7.23 - 7.40 4 H Multiple Ar -OH c 8.58 1 H Singlet -CH d 13.10 1 H Singlet - OH
72
FIG
. 3.3
4 : N
MR
SP
EC
TR
A O
F 3
-(4-
ME
TH
YL
PH
EN
YL
)-2-
(2-N
ITR
OP
HE
NY
L)-
1,3-
TH
IAZ
OL
IDIN
-4-O
NE
(D
KV-
3)
73
TABLE 3.13 : NMR SPECTRAL STUDY OF 3-(4-METHYLPHENYL)-2- (2-NITROPHENYL)-1,3-THIAZOLIDIN-4-ONE (DKV-3)
F
N
S
O
O2N
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
a 6.75 -7.32 4 H Multiple Ar - F
b 7.46 - 8.1 4 H Multiple Ar –NO2
c 3.74 - 3.92 2 H Singlet - CH2
d 2.9 - 3.0 1 H Singlet -CH
74
FIG
. 3.3
5 : N
MR
SP
EC
TR
A 2
-(2-
CH
LOR
OP
HE
NY
L)-3
- (4-
ME
THY
LPH
EN
YL)
-1,3
-TH
IAZO
LID
IN-4
-ON
E (
DK
V-4
)
75
TABLE 3.14 : NMR SPECTRAL STUDY OF 2-(2-CHLOROPHENYL)-3- (4-METHYLPHENYL)-1,3-THIAZOLIDIN-4-ONE (DKV-4)
F
N
S
O
Cl
Signal
No. Signal position
( δ ppm ) Relative No. Of Protons
Multiplicity
Inference
a 6.51 -7.01 4 H Multiple Ar - F
b 7.19 - 7.36 4 H Multiple Ar –Cl c 3.79 - 3.96 2 H Multiple - CH2
76
Mass spectral analysis :
A molecule is fragmented with excess of energy from an electron in mass
spectrum. The probability of cleavage of a particular bond is related to the bond
strength and to the stability of the fragments.
The mass spectrum provides information about
> The elemental composition of samples of matter,
> The structure of inorganic, organic and biological molecules,
> The qualitative and quantitative composition of solid surfaces and
> Isotopic ratios of atoms in samples.
Further, it provides data which cannot be obtained from other spectra.For
example, information about the C-skeleton from fragment peaks, functional groups
from high m/z peaks and characteristic ion series, to distinguish between cis and
trans isomers, to study reaction mechanisms, to study biochemical reaction,
measurement of ionization potential of bond strengths, quantitative analysis of
mixtures, study of polymeric compounds etc.
In this technique, gaseous ions are separated according to their mass to
charge (m/z) ratio. A mass spectrum is plot of relative abundance of the gaseous
component as a function of the mass to charge (m/z) of the components.
The mass spectra of Schiff bases and thiazolidinones were taken on
[JEOL SX 102/DA-6000] and GCMS - SHIMADZU - QP2010 spectrometer and
are shown in Figures 3.36 to 3.56. The proposed fragmentation patterns are given
in schemes 1 to 21.
77
FIG
. 3.
36 :
MA
SS
SP
EC
TR
A O
F 2
-[(4
- HY
DR
OX
YP
HE
NY
L)I
MIN
O]M
ET
HY
LP
HE
NO
L (
KP
V-1
)
79
F
IG.
3.37
: M
AS
S S
PE
CT
RA
OF
4-[
(2-C
HL
OR
OP
HE
NY
L)M
ET
HY
LE
NE
]AM
INO
PH
EN
OL
(K
PV
-2)
81
FIG
. 3.
38 :
MA
SS
SP
EC
TR
A O
F 4-
[(4
-ME
TH
OX
Y P
HE
NY
L)M
ET
HY
LE
NE
]AM
INO
PH
EN
OL
( K
PV
-3)
83
FIG
. 3.
39 :
MA
SS
SP
EC
TR
A O
F 4-
[(2
-NIT
RO
PH
EN
YL
)ME
TH
YL
EN
E]A
MIN
OP
HE
NO
L (
KP
V-4
)
85
FIG
. 3.
40 :
MA
SS
SP
EC
TR
A O
F 4-
[(3
-NIT
RO
PH
EN
YL
)ME
TH
YL
EN
E]A
MIN
OP
HE
NO
L (K
PV
-5)
89
FIG
. 3.
42 :
MA
SS
SP
EC
TR
A O
F 4
-[(
4-C
HL
OR
OP
HE
NY
L)M
ET
HY
LE
NE
]AM
INO
PH
EN
OL
(KP
V-7
)
91
FIG
. 3.
43 :
MA
SS
SP
EC
TR
A O
F 4-
[(4
-HY
DR
OX
Y P
HE
NY
L)I
MIN
O]M
ET
HY
L-
2-M
ET
HO
XY
PH
EN
OL
(K
PV
-8)
93
FIG
. 3.
44 :
MA
SS
SP
EC
TR
A O
F 2
-[(4
-FL
UO
RO
PH
EN
YL
)IM
INO
]ME
TH
YL
PH
EN
OL
(RK
V-1
)
95
FIG
. 3.
45 :
MA
SS
SP
EC
TR
A O
F 4
-[(4
-FL
UO
RO
PH
EN
YL
)IM
INO
]ME
TH
YL
PH
EN
OL
(RK
V-2
)
97
FIG
. 3.
46 :
MA
SS
SP
EC
TRA
OF
4-F
LUO
RO
-N-[
-(2-
NIT
RO
PH
EN
YL)
ME
THY
LEN
E]A
NIL
INE
(RK
V-3
)
99
FIG
. 3.
47 :
MA
SS
SP
EC
TR
A O
F N
-[-(
2-C
HL
OR
OP
HE
NY
L)M
ET
HY
LE
NE
]-4-
FL
UO
RO
AN
ILIN
E (R
KV
-4)
101
FIG
. 3.
48 :
MA
SS
SP
EC
TR
A O
F N
-[-(
4-C
HL
OR
OP
HE
NY
L)M
ET
HY
LE
NE
]-4-
FL
UO
RO
AN
ILIN
E (R
KV
-5)
103
FIG
. 3.
49 :
MA
SS
SP
EC
TR
A O
F 4
-[(4
-FL
UO
RO
PH
EN
YL
)IMIN
O]M
ET
HY
L-
N,N
-DIM
ET
HY
L- A
NIL
INE
(RK
V-6
)
104
SC
HE
ME
3.1
4 :
4-[
(4-F
LU
OR
OP
HE
NY
L)IM
INO
]ME
TH
YL
-N
,N-D
IME
TH
YL
- AN
ILIN
E (R
KV
-6)
105
FIG
. 3.
50 :
MA
SS
SP
EC
TR
A O
F 4
-FL
UO
RO
-N-[
(4-M
ET
HO
XY
PH
EN
YL
)ME
TH
YL
EN
E] A
NIL
INE
(RK
V-7
)
107
FIG
. 3.
51 :
MA
SS
SP
EC
TR
A O
F 4
-[(4
-FL
UO
RO
PH
EN
YL
)IM
INO
]ME
TH
YL
-2-
ME
TH
OX
YP
HE
NO
L (R
KV
-8)
109
FIG
. 3.
52 :
MA
SS
SP
EC
TR
A O
F (2
-HY
DR
OX
YP
HE
NY
L)-
3-(4
-ME
TH
YL
PH
EN
YL
)-1,
3-T
HIA
ZO
LID
IN- 4
-ON
E (D
KV-
1)
110
SC
HE
ME
3.1
7 : -
(2-H
YD
RO
XY
PH
EN
YL
)-3-
(4-M
ET
HY
LP
HE
NY
L)-
1,3-
TH
IAZ
OL
IDIN
- 4-O
NE
(DK
V-1)
111
FIG
. 3.
53 :
MA
SS
SP
EC
TR
A O
F 2
-(4-
HY
DR
OX
YP
HE
NY
L)-
3-(4
-ME
TH
YL
PH
EN
YL
)-1,
3-T
HIA
ZO
LID
IN- 4
-ON
E (D
KV-
2)
112
SC
HE
ME
3.1
8 : 2
-(4-
HY
DR
OX
YP
HE
NY
L)-
3-(4
-ME
TH
YL
PH
EN
YL
)-1,
3-T
HIA
ZO
LID
IN-4
-ON
E (D
KV-
2)
113
FIG
. 3.
54 :
MA
SS
SP
EC
TR
A O
F 3
-(4-
ME
TH
YL
PH
EN
YL
)-2-
(2-N
ITR
OP
HE
NY
L)-
1,3-
TH
IAZ
OL
IDIN
- 4-O
NE
(DK
V-3)
114
SC
HE
ME
3.1
9 : 3
-(4-
ME
TH
YL
PH
EN
YL
)-2-
(2-N
ITR
OP
HE
NY
L)-
1,3-
TH
IAZ
OL
IDIN
-4-O
NE
(DK
V-3)
115
FIG
. 3.
55 :
MA
SS
SP
EC
TR
A O
F 2
-(2-
CH
LO
RO
PH
EN
YL
)-3-
(4-M
ET
HY
LP
HE
NY
L)-
1,3-
TH
IAZ
OL
IDIN
- 4-
ON
E (
DK
V-4
)
116
SC
HE
ME
3.2
0 : 2
-(2-
CH
LO
RO
PH
EN
YL
)-3-
(4-M
ET
HY
LP
HE
NY
L)-
1,3-
TH
IAZ
OL
IDIN
-4-O
NE
(D
KV-
4)
117
FIG
. 3.
56 :
MA
SS
SP
EC
TR
A O
F 2
-(4-
CH
LO
RO
PH
EN
YL
)-3-
(4-M
ET
HY
LP
HE
NY
L)-
1,3-
TH
IAZ
OL
IDIN
- 4-O
NE
(D
KV-
5)
SC
HE
ME
3.2
1 :
2-(4
-CH
LO
RO
PH
EN
YL
)-3-
(4-M
ET
HY
LP
HE
NY
L)-
1,3-
TH
IAZ
OL
IDIN
-4-O
NE
(DK
V-5)
119
References :
[1] V.M. Parikh, “Absorption Spectroscopy of Organic Molecules”,Addission
Wesley Pub., 243-258 (1978).
[2] D. L. Pavia, G.M. Lampan and G.S. Kriz, “Introduction of spectroscopy”,
Saunders Publishng, Philadelphia, 46 (1979).
[3] R. M. Silverstein, G.S. Basseleo, and T.C. Manrill ; “Spectroscopic
Identification of Organic Compounds”, 4th Edn., John Wiley and Sons,
York.75.
120
Introduction :
The dissolution of a solute in a solvent is accompanied by the heat
change. If the heat is absorbed, i.e., the solution is cooler, the enthalpy change
(∆H) would be positive. If the heat is evolved, solution is warmer and so ∆H
would be negative. Thus, the heat of solution is defined as the change in
enthalpy, when one mole of substance is dissolved in specified quantity of
solvent at a given temperature. The molar heat of solution and melting
temperature of a substance can be determined from the solubility measurements
at different temperatures.
Literature survey shows that various workers studied thermodynamic
properties of several electrolytes in various pure and mixed solvents[1-8]. The heat
of solution for many organic and inorganic compounds, complexes, polymers etc.
have also been reported[9-19].
In the present work, heat of solution for the Schiff bases derived from
p-amino phenol was determined at 308.15 K in dimethylformamide (DMF) and
dimethylsulphoxide (DMSO).
121
Experimental :
The solvents used for the measurements were purified and fractionally
distilled prior to use by the method reported in the literature[20]. The solubility of
each Schiff base was determined by transferring 25 ml of saturated solution into
a pre-weighed 50 ml beaker at a definite temperature. The weight of beaker
along with solution was taken and the solvent was evaporated to dryness until
constant weight is obtained. This gives the weight of solute present in 25 ml
saturated solution. Three replicate measurements were carried out at a particular
temperature and average value of weight was determined. Subtraction of weight
of solute from the weight of solution gives the weight of solvent in 25 ml saturated
solution.
122
Results and Discussion:
The solubility (N2) of Schiff bases in both DMF and DMSO solvents are
given in Tables 4.1.1. It is observed that the solubility of Schiff bases is greater in
DMSO than in DMF. The dielectric constant (ε) of DMSO (ε = 46.6) is greater
than that of DMF (ε = 36.71). However, dipole moment of both the solvents,
DMSO and DMF are almost the same ( µ (DMSO) = 3.90 and µ (DMF) = 3.86).
Thus, dielectric constant of solvent plays an important role on the solubility of
studied Schiff bases.
In DMSO, the solubility is maximum for KPV-2 and minimum for KPV-5. In
DMF also, it is maximum for KPV-2 but minimum solubility is observed for KPV-1.
This suggests that the substituent groups also affect the solubility.
Further, Tables 4.1.1 shows that heat of solution are observed to be
positive for all the Schiff bases in both the solvents indicating thereby
endothermic behavior of these bases in both the solvents.
123
Table : 4.1.1 : The solubility and heat of solution of Schiff bases in DMF
and DMSO at 308.15 K.
DMF DMSO Compound code
N2 (.103 )
∆Hs (K.cal/mol)
N2 (.103 )
∆Hs (K.cal/mol)
KPV-1 0.0412 17.6899 0.0922 13.22557
KPV-2 0.0974 14.9156 0.1032 14.54788
KPV-3 0.0659 12.9253 0.0798 12.01739
KPV-4 0.0670 12.7806 0.0926 11.24671
KPV-5 0.0540 14.0998 0.0786 12.28948
KPV-6 0.0458 11.8315 0.0950 9.032239
KPV-7 0.0431 12.2403 0.0841 9.63699
KPV-8 0.0521 12.8982 0.0926 10.38911
124
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1673.
[10] I. R. Tasker, S. K. Suri and R. H. Wood, J. Chem. Eng. Data, 29 (1984)
193.
[11] D. G. Archer, H. J. Albert, D. E. White and R. H. Wood, J. Colloid Inter.
Sci., 100 (1984) 68.
[12] H. F. Holmes, R. H. Busey, J. M. Simonson, R. E. Mesmer, D. G. Archer
and R. H. wood, J. Chem. Thermodyn., 19, (1987) 863.
[13] N. U. Meurs, W. T. Warmerdam and G. Somsen, Fluid Phase Equi., 46
(1989) 263.
[14] P. H. Parsania, Asian J. Chem., 5 (1993) 312.
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125
[17] J. M. Romero, L. C. Leiva, N. L. Jorge, M. E. Gomez Vara, E. A. Castro,
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Phys., 6 (2004) 822.
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597, (2005) 181.
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Properties and Methods for Purification”, 4th Edition, Vol.II, Wiley
Interscience, New York.
126
Introduction :
The measurement of density is useful in determining the purity of
substances. The determination of density of certain physiological liquids is
often an important screening tool in medical diagnosis.
Literature survey shows that much work has been done in liquid
mixtures [1-13] but scanty work has been reported for the solutions, which
include solutions of organic, inorganic and polymeric materials [14-27].
Thus, in the present chapter, the density of all the Schiff bases derived
from p-amino phenol are determined in dimethylformamide (DMF) and
dimethylsulfoxide (DMSO) solutions at 308.15 K.
127
Experimental:
The solvents DMF and DMSO were purified and fractionally distilled
prior to use [28].
All the Schiff bases were recrystallized from methanol. For each Schiff
base a series of solutions were prepared of different concentrations in both
the solvents. The density of all the solutions was measured by Pyknometer at
308.15 K. The results are given in Tables 4.2.1.
Results and Discussion : The density of solution (ρ12) is related to densities of the solvent, solute
and their weight fractions g1 and g2, according to the equation:
1/ρ12 = g1/ρ1 + g2/ρ2 ……….(4.2.1)
where ρ12 is density of solution and ρ1 and ρ2 are the densities of the solvent
and solute respectively. The obtained density results in Tables 4.2.1 are
related to a first order polynomial with respect to concentration in the following
form
ρ = a + bc ………..(4.2.2)
where ρ is density, c is concentration and a and b are coefficients of above
linear equation. The values of coefficients a and b and correlation coefficient
(γ) for all the Schiff bases are given in Table 4.2.2.
The calculated g1 and g2 values in DMF and DMSO solutions are
reported in Table 4.2.3 and 4.2.4 respectively. From the plot of 1/ρ12g1 verses
g2/g1, the density of Schiff bases were calculated. Figures 4.2.1 and 4.2.2
show the plots of 1/ρ12g1 verses g2/g1 in DMF and DMSO respectively. The
inverse of slope gives the density of Schiff base (ρ2). All these densities are
given in Table 4.2.5.
The density of a compound can also be determined theoretically by
following equation [29].
ρ = KM / NAΣ∆Vi ………. (4.2.3)
where ρ the density of the compound, K is is packing fraction (0.60), is the
molecular weight of the compound, NA is the Avogadro’s number and ∆Vi is
the volume increment of the atoms and atomic groups present in the
compound. ∆Vi for some of the atoms and group of atoms are given in Table
4.2.6. The densities calculated from equations (4.2.2) are given in Table 4.2.5.
129
It is observed from Table 4.2.5 that in some cases, there is quite good
agreement between theoretical and experimental density values where as in
others, deviations between theoretical and experimental densities are larger.
It is reported in section - 5 that in solutions, molecular interactions exist.
Usually intermolecular interactions do not affect the density but due to
polar substituent, there may be change in volume as well as in the molecular
weight of the compound. Thus, the deviations between experimental and
calculated values again confirm the existence of intermolecular interactions
between solute and solvent molecules.
130
Table 4.2.1: The density (ρ12) of Schiff bases in DMF and DMSO solutions at
308.15 K.
Density g * cm-3 Conc. ( M ) DMF
KPV-1 KPV-2 KPV-3 KPV-4 KPV-5 KPV-6 KPV-7 KPV-8
0.00 0.9356 0.9356 0.9356 0.9356 0.9356 0.9356 0.9356 0.9356
0.01 0.9366 0.9382 0.9380 0.9408 0.9382 0.9412 0.9373 0.9439
0.02 0.9378 0.9388 0.9404 0.9414 0.9403 0.9414 0.9397 0.9446
0.04 0.9386 0.9401 0.9429 0.9433 0.9412 0.9430 0.9431 0.9457
0.06 0.9396 0.9411 0.9444 0.9441 0.9422 0.9438 0.9441 0.9476
0.08 0.9405 0.9413 0.9452 0.9446 0.9444 0.9453 0.9479 0.9480
0.10 0.9413 0.9416 0.9472 0.9459 0.9482 0.9459 0.9498 0.9487
DMSO
0.00 1.0853 1.0853 1.0853 1.0853 1.0853 1.0853 1.0853 1.0853
0.01 1.0879 1.0887 1.0907 1.0926 1.0925 1.0940 1.0918 1.0928
0.02 1.0886 1.0890 1.0909 1.0930 1.0937 1.0946 1.0922 1.0935
0.04 1.0889 1.0893 1.0922 1.0937 1.0942 1.0949 1.0924 1.0954
0.06 1.0892 1.0899 1.0926 1.0945 1.0944 1.0956 1.0925 1.0957
0.08 1.0896 1.0901 1.0960 1.0963 1.0953 1.0969 1.0927 1.0962
0.10 1.0899 1.0912 1.0971 1.0976 1.0953 1.0971 1.0929 1.0965
131
Table 4.2.2 : Coefficients a and b obtained for DMF and DMSO solutions of
Schiff bases.
DMF Schiff bases
a b γ
KPV - 1 0.8205 1.0678 0.9982
KPV - 2 0.8890 1.0659 0.9963
KPV - 3 0.6288 1.0659 0.9738
KPV – 4 0.8234 1.0632 0.9971
KPV – 5 0.9245 1.0636 0.9493
KPV – 6 0.7487 1.0632 0.9975
KPV – 7 0.7496 1.0676 0.9598
KPV - 8 0.8208 1.0598 0.9967
DMSO
KPV - 1 0.8355 0.9191 0.9994
KPV - 2 0.8185 0.9188 0.9992
KPV - 3 0.6185 0.9179 0.9835
KPV – 4 0.7067 0.9160 0.9972
KPV – 5 0.8084 0.9151 0.9976
KPV – 6 0.7414 0.9143 0.9980
KPV – 7 0.8739 0.9159 0.9998
KPV - 8 0.7632 0.9150 0.9945
132
Table 4.2.3 : The weight fractions g1 and g2 of Schiff bases in DMF solutions at
308.15 K.
Conc. (M) g1 g2 g1 g2 g1 g2 g1 g2
KPV - 1 KPV - 2 KPV - 3 KPV - 4
0.01 0.9977 0.0023 0.9975 0.0025 0.9976 0.0024 0.9974 0.0026
0.02 0.9954 0.0046 0.9951 0.0049 0.9952 0.0048 0.9948 0.0052
0.04 0.9909 0.0091 0.9901 0.0099 0.9903 0.0097 0.9897 0.0103
0.06 0.9864 0.0136 0.9852 0.0148 0.9855 0.0145 0.9846 0.0154
0.08 0.9818 0.0182 0.9803 0.0197 0.9807 0.0193 0.9794 0.0206
0.10 0.9773 0.0227 0.9753 0.0247 0.9760 0.0240 0.9743 0.0257
KPV - 5 KPV - 6 KPV - 7 KPV - 8
0.01 0.9974 0.0026 0.9980 0.0020 0.9975 0.0025 0.9974 0.0026
0.02 0.9948 0.0052 0.9960 0.0040 0.9951 0.0049 0.9948 0.0052
0.04 0.9897 0.0103 0.9920 0.0080 0.9902 0.0099 0.9897 0.0103
0.06 0.9573 0.0427 0.9881 0.0119 0.9853 0.0148 0.9846 0.0154
0.08 0.9794 0.0206 0.9841 0.0159 0.9804 0.0196 0.9794 0.0206
0.10 0.9744 0.0256 0.9802 0.0198 0.9756 0.0244 0.9743 0.0257
133
Table 4.2.4 : The weight fractions g1 and g2 of Schiff bases in DMSO
Solutions at 308.15 K.
Conc. (M)
g1 g2 g1 g2 g1 g2 g1 g2
KPV - 1 KPV - 2 KPV - 3 KPV - 4
0.01 0.9980 0.0020 0.9979 0.0021 0.9979 0.0021 0.9978 0.0022
0.02 0.9960 0.0040 0.9957 0.0043 0.9958 0.0042 0.9956 0.0044
0.04 0.9920 0.0080 0.9915 0.0085 0.9917 0.0083 0.9911 0.0089
0.06 0.9880 0.0120 0.9872 0.0128 0.9875 0.0125 0.9867 0.0133
0.08 0.9840 0.0160 0.9830 0.0170 0.9834 0.0166 0.9823 0.0177
0.10 0.9800 0.0200 0.9787 0.0213 0.9792 0.0208 0.9779 0.0221
KPV - 5 KPV - 6 KPV - 7 KPV - 8
0.01 0.9978 0.0022 0.9983 0.0017 0.9979 0.0021 0.9978 0.0022
0.02 0.9956 0.0044 0.9966 0.0034 0.9957 0.0043 0.9955 0.0045
0.04 0.9911 0.0089 0.9932 0.0069 0.9915 0.0085 0.9911 0.0089
0.06 0.9867 0.0133 0.9898 0.0103 0.9873 0.0127 0.9867 0.0133
0.08 0.9823 0.0177 0.9863 0.0137 0.9830 0.0170 0.9822 0.0178
0.10 0.9779 0.0222 0.9829 0.0171 0.9788 0.0212 0.9778 0.0222
134
Fig. 4.2.1 : The plots of 1/ρ12g1 against g2/g1 for [A] KPV - 1 and [B] KPV - 2
in DMF at 308.15 K.
135
Fig. 4.2.2 : The plots of 1/ρ12g1 against g2/g1 for [A] KPV - 1 and [B] KPV - 2 in
DMSO at 308.15 K.
136
Table 4.2.5 : Experimental and calculated densities of Schiff bases in DMF
and DMSO solutions at 308.15 K.
Density gm/cm3 Solvents
Density gm/cm3
Compounds DMF
DMSO
Calculated from eqn. (4.2.3)
KPV - 1 1.3000 1.2727 1.1287
KPV - 2 1.1765 1.2000 1.1722
KPV - 3 1.6812 1.3572 1.1086
KPV - 4 1.2820 1.4285 1.1931
KPV - 5 1.5263 1.1800 1.1931
KPV - 6 1.5190 1.3530 1.3899
KPV - 7 1.2658 1.1210 1.1722
KPV - 8 1.2358 1.2000 1.0771
137
Table 4.2.6 : Volume increments of some atoms and groups of atoms.
Atom or Volume Atom or Volume Atomic group Increment Atomic group Increment Vi (A0)3 Vi (A0)3 3.52 1.25
2.7 1.02 7.46 8.40 14.70 3.60 8.40 2.66 5.62 26.30
1.08 OH
C
C
1.4
H
C
1.484
C
C
1.4
1.281.37
N C
C
1.4
C
C
1.37
N
C
1.41.48C C
C
C
N C C
H
1.08
1.484
1.37 CH31.50
C Oar
1.5 H
H
H
O C1.08
1.08
1.08
ar
H
CCN
1.5 1.5O
C C
O
O
NC1.37
1.217
138
Continue…(Table 4.2.6) Atom or Volume Atom or Volume Atomic group Increment Atomic group Increment Vi (A0)3 Vi (A0)3 11.65 5.6 10.10 7.84 19.35
12.641.48Car
O
C C 1.50
1.40
C1.27
O 7.29
C1.27
C 1.090.58
1.13
OC
CarC
ClCar1.77
1.37arC HO
1.08
1.4C C
C
C1.28
OC1.4
1.771.4 C Cl
C
139
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141
Introduction:
Electrical conduction is a property of ionic solutions. The conductance of
electrolytic solutions depends on the concentration of the ions and also on the
nature of the ions present (through their charges and mobilities), and
conductance behavior as a function of concentration is different for strong and
weak electrolytes.
In physical chemistry, this technique is also used for determining the
ionization constant of weak electrolytes, in determining equilibrium constant and
rates of reactions that proceed with the formation or disappearance of ions, in
titration of solutions and in studies of interionic forces. Mullyniemi et al.[1] have
used an indirect conductometric screening method for the detection of antibiotic
residues in bovine kidneys. Sawai et al.[2] have used this technique to
investigate the growth of fungi. Literature survey shows that conductance of
many organic and inorganic compounds[3-17] have been measured in aqueous
and non-aqueous solvents, but very less data is available for Schiff bases and
their metal complexes[18-25]. Recently, conductances of some Schiff bases in
DMF and DMSO have been measured at different temperatures by Grzeszcuk
and Bator[26]. Further, in our laboratory, some conductance measurements have
been done for Schiff bases[27, 28].
The conductances of some Schiff bases of p-amino phenol are measured
in DMF and DMSO solutions at 308.15 K. The selection of these two solvents is
due to their dipolar aprotic characteristics, which avoid any proton interference
with the conductivity of complex systems[11]. The solubility restriction in media of
high dielectric constant does not allow for characterization of transport properties
in solvents of a wide range of varying dielectric constants.
142
Experimental : All the solvents used were distilled prior to use. The solutions of different
concentrations were prepared for each Schiff base in DMF and DMSO. The
conductance of each solution was measured by using Systronics Conductivity
Meter (Model No. 306) having cell constant 0.85 cm-1 at 308.15 K. The
conductance of each solution was corrected by subtracting conductance of pure
solvent.
143
Results and Discussion :
The measured conductance (C) for all the solution, after correction, was
used to determine the specific conductance κ, from which equivalent
conductance λC was calculated by the equation
κ = C θ ….. (4.3.1)
where θ is the cell constant.
λC = 1000 κ / c ..… (4.3.2)
where c is the concentration (g.equi/lit) of the solutions. The calculated values are
reported in Tables 4.3.1 and 4.3.2 for all Schiff bases derived from p-amino
phenol in DMF and DMSO at 308.15 K respectively. It is evident from Tables 4.3.1
and 4.3.2 that for all Schiff bases, equivalent conductance increases with dilution
in both the solvents. Further, It is observed that the values of λC are higher for
DMF than those in DMSO solutions. The equivalent conductance values
decreases in the following order :
In DMF : KPV-4 > KPV-2> KPV-3 > KPV-1 > KPV-5 > KPV-6 >KPV- 8 > KPV-7.
In DMSO : KPV-1 > KPV-7 >KPV-8 > KPV-2 > KPV- 6 > KPV-4 >KPV-5 > KPV-3.
It is observed that in DMF, the equivalent conductance of KPV- 4 is
maximum over the wide range of concentration whereas minimum λC is observed
in KPV-7. However, in DMSO, highest λC value is observed in KPV- 1 whereas
low λC is observed in KPV-3. This suggests that conducting behavior of Schiff
base depends on solvent and nature of solute under study rather than on its
molecular weight [12].
Due to different substituents present, conductance varies differently in
different solvents due to interaction between solute and solvent molecules. This is
explained in chapter-IV, section-5.
In DMF, presence of nitro group increases the equivalent conductance
whereas p-choloro substitution decreases the conductivity. However, in DMSO,
144
Table 4.3.1 The conductance (C) and equivalent conductance (λC) of Schiff bases in DMF at 308.15 K .
Conc. c
(gm/lit)
C. 105
(Ω)-1 λC
(cm2/Ω.equiv.)C. 105
(Ω)-1 λC
(cm2/Ω.equiv.)C. 105
(Ω)-1 λC
(cm2/Ω.equiv.)C. 105
(Ω)-1
λC (cm2/Ω.equiv.)
KPV - 1 KPV - 2 KPV - 3 KPV - 4 0.001 0.0500 0.4250 0.0585 0.4973 0.0549 0.4667 0.7100 6.0350 0.002 0.0610 0.2593 0.0653 0.2775 0.0574 0.2440 0.7470 3.1748 0.004 0.0780 0.1658 0.0749 0.1592 0.0616 0.1309 0.8010 1.7021 0.006 0.0960 0.1360 0.0833 0.1180 0.0647 0.0917 0.8420 1.1928 0.008 0.1260 0.1339 0.0906 0.0963 0.0679 0.0721 0.8850 0.9403 0.010 0.1550 0.1318 0.0969 0.0824 0.0699 0.0594 0.9210 0.7829 0.020 0.3000 0.1275 0.1310 0.0557 0.0800 0.0340 1.0900 0.4633 0.040 0.5310 0.1128 0.1850 0.0393 0.0800 0.0170 1.2000 0.2550 0.060 0.6300 0.0893 0.2130 0.0302 0.0833 0.0118 1.3900 0.1969 0.080 0.7330 0.0779 0.2250 0.0239 0.1320 0.0140 1.6000 0.1700 0.100 0.8590 0.0730 0.2390 0.0203 0.1350 0.0115 1.1700 0.0995
KPV - 5 KPV - 6 KPV - 7 KPV - 8 0.001 0.0504 0.4284 0.0181 0.1539 0.0088 0.0748 0.0110 0.0935 0.002 0.0652 0.2771 0.0247 0.1050 0.0111 0.0472 0.0144 0.0612 0.004 0.0678 0.1441 0.0381 0.0810 0.0149 0.0317 0.0200 0.0425 0.006 0.0694 0.0983 0.0492 0.0697 0.0181 0.0256 0.0232 0.0329 0.008 0.0717 0.0762 0.0594 0.0631 0.0214 0.0227 0.0268 0.0285 0.010 0.0731 0.0621 0.0673 0.0572 0.0237 0.0201 0.0355 0.0302 0.020 0.0828 0.0352 0.1040 0.0442 0.0374 0.0159 0.0565 0.0240 0.040 0.1000 0.0213 0.1538 0.0327 0.0623 0.0132 0.0941 0.0200 0.060 0.1190 0.0169 0.1821 0.0258 0.0794 0.0112 0.1180 0.0167 0.080 0.1300 0.0138 0.2124 0.0226 0.0991 0.0105 0.1530 0.0163 0.100 0.1410 0.0120 0.2500 0.0213 0.1160 0.0099 0.1900 0.0162
145
Table 4.3.2: The conductance (C) and equivalent conductance (λC) of Schiff bases in DMSO at 308.15 K.
Conc. c
(gm/lit)
C. 105
(Ω)-1 λC
(cm2/Ω.equiv.)C. 105
(Ω)-1 λC
(cm2/Ω.equiv.)C. 105
(Ω)-1 λC
(cm2/Ω.equiv.)C. 105
(Ω)-1
λC (cm2/Ω.equiv.)
KPV - 1 KPV - 2 KPV - 3 KPV - 4 0.001 0.0760 0.6460 0.0323 0.2746 0.0152 0.1292 0.0230 0.1955 0.002 0.1310 0.5568 0.0674 0.2865 0.0178 0.0757 0.0295 0.1254 0.004 0.1860 0.3953 0.0839 0.1783 0.0242 0.0514 0.0421 0.0895 0.006 0.2340 0.3315 0.1050 0.1488 0.0263 0.0373 0.0434 0.0615 0.008 0.2480 0.2635 0.2160 0.2295 0.0314 0.0334 0.0452 0.0480 0.010 0.2580 0.2193 0.3320 0.2822 0.0357 0.0303 0.0475 0.0404 0.020 0.2610 0.1109 0.4280 0.1819 0.0477 0.0203 0.0519 0.0221 0.040 0.3480 0.0740 0.5860 0.1245 0.0808 0.0172 0.0777 0.0165 0.060 0.4110 0.0582 0.7340 0.1040 0.1090 0.0154 0.1050 0.0149 0.080 0.4860 0.0516 0.8790 0.0934 0.1440 0.0153 0.1310 0.0139 0.100 0.6320 0.0537 0.9150 0.0778 0.1660 0.0141 0.1550 0.0132
KPV - 5 KPV - 6 KPV - 7 KPV - 8 0.001 0.0240 0.2040 0.0260 0.2210 0.0596 0.5066 0.0395 0.3358 0.002 0.0271 0.1152 0.0333 0.1415 0.0760 0.3230 0.0424 0.1802 0.004 0.0332 0.0706 0.0454 0.0965 0.0842 0.1789 0.0486 0.1033 0.006 0.0366 0.0519 0.0569 0.0806 0.0901 0.1276 0.0539 0.0764 0.008 0.0423 0.0449 0.0682 0.0725 0.0995 0.1057 0.0590 0.0627 0.010 0.0438 0.0372 0.0704 0.0598 0.1060 0.0901 0.0617 0.0524 0.020 0.0465 0.0198 0.1080 0.0459 0.1160 0.0493 0.0876 0.0372 0.040 0.0580 0.0123 0.1930 0.0410 0.1620 0.0344 0.1260 0.0268 0.060 0.0676 0.0096 0.2820 0.0400 0.1670 0.0237 0.1660 0.0235 0.080 0.0728 0.0077 0.3490 0.0371 0.1740 0.0185 0.1920 0.0204 0.100 0.0810 0.0069 0.4250 0.0361 0.1920 0.0163 0.2310 0.0196
146
presence of –OH group increases while methoxy group decreases the equivalent
conductance.
The plots of equivalent conductance verses √c are given in Figure 4.3.1 in
both the solvents. It is clear from these figures that almost all Schiff bases are
weak electrolytes in nature.
For weak electrolytes, the equivalent conductance at infinite dilution (λ0)
can not be calculated by extrapolation of λC verses √c plots. However, we have
tried to determine λ0 values, by extrapolating these plots. These λ0 values are
given in Table 4.3.3. Singh et al[11] reported an alternative procedure to calculate
λ0 values for poly electrolytes. For the present systems, the same procedure was
tried to determine λ0 by the following equation:
κ = κ0 + λ0 c+ c φ(c) …………. (4.3.3)
where κ and κ0 are the electrolytic conductivities of the solutions and solvent
respectively. c is the equivalent concentration and the function φ(c) denotes the
effect of interionic interactions. The slope dκ/dc of the plot of κ verses c
approximates the limiting conductivity (λ0), provided other derivatives dκ0/dc and
d[cφ(c)]/dc in the differential form of equation (4.3.4) are neglected as compared
to λ0.
dκ/dc = dκ0/dc+ λ0 + d/dc [c φ(c)] ----- (4.3.4)
Figures 4.3.2 shows the variation of corrected conductance with
concentration for all Schiff bases in both DMF and DMSO at 308.15 K. It is clear
from the figures that in lower concentration range i.e., up to 0.01M, conductance
varies almost linearly with concentration for all the Schiff bases. However, non-
linearity is observed at higher concentration i.e. above 0.01M.
147
Figure 4.3.1: The plots of equivalent conductance verses √c for Schiff bases in
DMF and DMSO at 308.15 K.
DMF -KPV-1
0.0
0.3
0.6
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
DMSO -KPV-1
0.0
0.4
0.8
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
DMF-KPV-2
0.0
0.3
0.6
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
DMSO-KPV-2
0.00
0.15
0.30
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
DMF-KPV-3
0.0
0.3
0.6
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
DMSO-KPV-3
0.00
0.08
0.16
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
148
Figure 4.3.1: (contd.)…..
DMF-KPV-4
0
4
8
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
DMSO-KPV-4
0.00
0.12
0.24
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
DMF-KPV-5
0.0
0.3
0.6
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
DMSO-KPV-5
0.00
0.12
0.24
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
DMF-KPV-6
0.00
0.10
0.20
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
DMSO-KPV-6
0.00
0.12
0.24
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
149
Figure 4.3.1: (contd.)…..
DMF-KPV-7
0.00
0.04
0.08
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
DMSO-KPV-7
0.0
0.3
0.6
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
DMF-KPV-8
0.00
0.06
0.12
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
DMSO-KPV-8
0.0
0.2
0.4
0.0 0.2 0.4
C
equi
. con
d. (m
ho.c
m.2 /e
qui.)
150
Figure 4.3.2: Variation of conductance with concentration for Schiff bases in
DMF and DMSO at 308.15 K.
DMF -KPV-1
0.0
0.5
1.0
0.00 0.06 0.12
Concentration (M)
Con
duct
ance
. 10
5 (mho
) DMSO -KPV-1
0.0
0.5
1.0
0.00 0.06 0.12
Concentration (M)
cond
ucta
nce
. 105 (m
ho)
DMF-KPV-2
0.0
0.2
0.4
0.00 0.06 0.12
Concentration (M)
Con
duct
ance
. 10
5 (mho
)
DMSO-KPV-2
0.0
0.5
1.0
0.00 0.06 0.12
Concentration (M)
cond
ucta
nce
. 105 (m
ho)
DMF-KPV-3
0.00
0.08
0.16
0.00 0.06 0.12
Concentration (M)
cond
ucta
nce
. 105 (m
ho)
DMSO-KPV-3
0.00
0.10
0.20
0.00 0.06 0.12
Concentration (M)
cond
ucta
nce
. 105 (m
ho)
151
Figure 4.3.2: (contd.)…..
DMF-KPV-4
0.0
1.0
2.0
0.00 0.06 0.12
Concentration (M)
con
dduc
tanc
e . 1
05 (mho
)
DMSO-KPV-4
0.00
0.10
0.20
0.00 0.06 0.12
Concentration (M)
cond
ucta
nce
. 105 (m
ho)
DMF-KPV-5
0.00
0.08
0.16
0.00 0.06 0.12
Concentration (M)
cond
ucta
nce
. 105 (m
ho)
DMSO-KPV-5
0.00
0.05
0.10
0.00 0.06 0.12
Concentration (M)
cond
ucta
nce
. 105 (m
ho)
DMF-KPV-6
0.00
0.12
0.24
0.00 0.06 0.12
Concentration (M)
con
duct
ance
. 10
5 (mho
)
DMSO-KPV-6
0.0
0.3
0.6
0.00 0.06 0.12
Concentration (M)
cond
ucta
nce
. 105 (m
ho)
152
Figure 4.3.2: (contd.)…..
DMF-KPV-7
0.00
0.06
0.12
0.00 0.06 0.12
Concentration (M)
cond
ucat
nce
. 105 (m
ho)
DMSO-KPV-7
0.00
0.10
0.20
0.00 0.06 0.12
Concentration (M)
cond
ucta
nce
. 105 (m
ho)
DMF-KPV-8
0.00
0.08
0.16
0.00 0.06 0.12
Concentration (M)
con
duct
ance
. 10
5 (mho
)
DMSO-KPV-8
0.00
0.12
0.24
0.00 0.06 0.12
Concentration (M)
cond
ucta
nce
. 105 (m
ho)
153
As interionic interactions are present in all the systems over the wide
range of concentrations, so the derivative d[cφ(c)]/dc cannot be ignored in
comparison to λ0. However, limiting equivalent conductivities were evaluated
from the limiting slope of small linear portions of the κ verses c curve, assuming
that the interionic interactions in this range of concentration are limited. For all
the systems, the calculated λ0 values are given in Table 4.3.3. It is evident from
Table 4.3.3 that except for KPV - 5 and KPV - 8 in DMF, deviations are quite high
between the values evaluated from graph and those calculated by eq. 4.3.3. This
suggests that for the studied Schiff bases, eq. ( 4.3.3 ) is not valid.
154
Table 4.3.3: The limiting equivalent conductance (λ0) for all Schiff bases in DMF and
DMSO at 308.15 K.
DMF DMSO Compound
Code λo
( cm2/Ωequiv.)
λo
( cm2/Ωequiv.)
calc. by eq. (4.3.2)
λo
( cm2/Ωequiv.)
λo
( cm2/Ωequiv.)
calc. by eq. (4.3.2)
KPV - 1
KPV - 2
KPV - 3
KPV - 4
KPV - 5
KPV - 6
KPV - 7
KPV - 8
8.18
3.91
1.40
22.50
1.25
5.24
1.60
0.27
0.70
0.95
0.75
13.70
1.30
0.33
0.15
0.19
2.50
1.61
2.24
1.07
2.43
5.86
3.75
2.71
0.86
0.38
0.22
0.32
0.45
0.40
1.10
0.78
155
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157
Introduction :
The dissociation constants are used to measure the strength of acid
and bases. They are also known as acidity constant, ionization constant or
formation constant.
Since long chemists have concerned themselves with the development
of precise methods of measuring acidity constants. In general terms, any
physical property, which varies with protonation, may provide a suitable
method for the measurement of dissociation constants.
The dissociation or acidity constant is determined by determining one
of the species, at equilibrium. The activity or concentration of the others can
be calculated from the amount of the acid or base initially introduced and the
stoichiometry of the acid base equilibrium. As the equilibrium is highly mobile,
physical methods, which do not disturb the equilibrium, are preferred for the
determination of the equilibrium concentration of the species present. For the
measurement of dissociation constant, various methods have been
developed [1], such as: (i) potentiometry including pH metry, (ii) spectrophoto-
metry, (iii) conductometry, (iv) solubility measurements[1], (v) cryoscopy[2],
(vi) measurement of the relative distribution of an acid between two immiscible
solvents[3], (vii) measurements of the rates of acid catalyzed hydrolysis of
esters[4], (viii) magnetic measurements etc. Recently, some new methods
such as capillary electrophoresis[5-7], Ikuta and Hirokawa[8] , feedback-based
flow ratiometry[8,9], UV visible[10] , mass spectrometry[11] etc. have also been
used to determine acid dissociation constant. The use of Raman spectra and
nuclear magnetic constants are also known to be used for a number of acids,
which are regarded as strong in aqueous solution [10, 12, 13].
For very week acids, conductance method was used, which was more
time consuming[4]. When the acid is sparingly soluble and acid strengths are
very high or very low. Spectrophotometer method is considered to be an ideal
method, but this method is also more time consuming. It is applicable if at
least one of the species at equilibrium absorbs characteristically in the
ultraviolet or visible region and the relevant ionic species show absorption
maxima at different wavelengths.
158
The most time economical method is potentiometry, which is mostly used
for the determination of dissociation constants of acids. Further, it can be used
for acids of pKa range from 2 to 11 units[12]. The calomel and glass electrodes
are used for the measurement[4] and carbonate free potassium hydroxide is the
best alkali to use as a titrant.
The potential generated by the hydrogen ions, in the solution of an acid in
a given medium is measured by an electronic potentiometer assembly. The
relationship between the potential of glass electrode and the pH of the solution
has the general form:
-log [H+] = pH = E0 – Ec / 0.0591 at 250C
where E0 is the observed potential and Ec is the potential of the calomel
electrode. All these terms in above equation change with time. So, it must be
calibrated before and after use with a pair of known buffers, the pH of one of
which must lie near to the pH region to be measured. The correctness of the
results depends upon the exactness of the calibration of pH-meter. The
reference solutions of known pH are preferred due to three primary reasons [14].
1. Saturated calomel reference electrodes are not highly reproducible
and this is particularly true for small immersion type electrode.
2. The potentials of the commercial glass electrodes vary widely and the
symmetry potentials may fluctuate from day to day.
3. The pH meter is usually calibrated to read directly in pH units.
Accurate results cannot be expected if pKa to be determined is very low.
In such cases, more sensitive instruments should be used.
The pH metric methods measure directly the activity of the hydrogen
ions. So, one can get reliable values of dissociation constant by this method.
This method is very popular although there are certain difficulties in mixed
aqueous media and non-aqueous media. The solubility method for determining
pKa is not so accurate as conductometric, potentiometric or spectrophotometric
technique, but is useful in cases where the substance is too insoluble in water
for conductometric or potentiometric methods.
159
There are many applications of dissociation constants. The nature of
the functional groups can be determined by simple comparison of acidity or
dissociation constant of the unknown compound with those of known
compounds. The dissociation or formation constant also provides useful
information about structure, tautomeric equilibria, solvent-solute interactions
etc.[15]. By determining dissociation constants, Prenesti et al. interpreted acid–
base properties of grape red wines [16].
Generally, the formation constant and other thermodynamic properties
of water-insoluble compounds are measured in purely non-aqueous organic
solvent or in a mixture of two solvents, one of which may be water. A solvent
mixture containing water and water-miscible organic solvent is known as mixed
aqueous medium. A number of works has been done in non-aqueous and
mixed-aqueous media [17-23].
Various workers studied the dissociation constant of many
substances[24-28] by using different methods. Grunwald[29] measured ionization
of formic acetic and benzoic acid by differential potentiometry. Czaja et al also
used this technique for the determination of dissociation constant of substituted
phenols[30]. Sandhu[31] used pH metry for the determination of stability
constants of some complexes.
The ionization constants of various other acids in pure and mixed
solvents have also been studied [32-39].
Pardeshi and Bhobe reported dissociation constants of some amino
acids[40]. Arora et al[41]., reported the dissociation constant of some hydroxyl
coumarins in ethanol-water mixtures. Etxebarria et al. determined the
protonation constant of 4-methylpyridine in potassium nitrate-toluene
systems[42]. Palanichamy[43] studied the dissociation constants of some
aliphatic acids and amino acids by potentiometry. Rengaraj et al. and others
determined formation constant of some Schiff bases and their metal
complexes[44]. Robert et al.[45] reported the acidity constants of benzidine and
N,N-dimethylbenzidine. Boraei and Ahmed[46] studied formation constant of
transition metal ion mixed complexes of tricine and 8-hydroxy quinoline.
A computer programme was also reported to determine conditional
formation constant of carbonic acid in sea water[47]. Ghaseni et al[48] studied
160
the acidity constant of 4-(2-pyridylazo)resorcinol in acetonitrile-water mixtures.
The dissociation constant of some biologically active sulfonamides have also
been reported by Remko and Lieth[49]. Partanen and Covington reported the
dissociation constants from electrochemical cell data for propionic acid and n-
butyric acids and some aliphatic carboxylic acids in aqueous sodium chloride
solutions[50].
In the present work, the dissociation constants of some Schiff bases
are studied in 1, 4- dioxane-water (60:40 v/v) mixture at 308.15 K.
161
Experimental :
The chemicals used were of B.D.H Analar grade. All solutions used for
the titration are prepared using distilled water. Following are the
concentrations of the solutions used for the titration.
Solutions Concentration (M) Nitric acid 0.1
Sodium hydroxide 0.5, 0.1
Sodium nitrate 1.0
Schiff base (in 1,4-dioxane) 0.1
Nitric acid and sodium hydroxide were standardized by titrating with
0.1 N NaOH and 0.05 M succinic acid solution respectively.
The 1, 4-dioxane used was of S. Merck and was purified by the reported
method [51].
The buffer solutions used for the calibration of pH meter were 0.05 M
potassium hydrogen phthalate and 0.01 M Borax buffer.
A systronic pH meter (Model No. EQ 664) was used for the pH
determination. The systronic glass electrode and a saturated calomel
electrode were used as indicator and reference electrodes respectively.
Before operation, the glass electrode was immersed in 0.1 M HCl for twenty
minutes. Then, it was washed thoroughly with distilled water.
Before measurement, the pH meter was calibrated with buffer solution of
known pH.
162
Calvin Bjerrum pH titration :
The following sets of mixtures were prepared for titration:
(I) 0.8 ml HNO3 (0.1M) + 11.2 ml water + 24.0 ml 1, 4-dioxane + 4.0 ml
NaNO3 (1.0 M).
(ii) 0.8 ml HNO3 (0.1M) + 11.2 ml water + 22.0 ml 1, 4-dioxane + 2.0 ml
ligand solution (0.1M) + 4.0 ml NaNO3 (1.0 M).
Thus, total volumes (V0) in each set = 40.0 ml and 1, 4-dioxane: water
ratio 60:40 (v/v).
The above mentioned solutions were allowed to attain a constant
temperature (308.15 K) and then titrated against standard NaOH solution (0.5
M) under an inert atmosphere of nitrogen. The change in the pH of solution
with each addition of alkali was recorded and is given in Tables 4.4.1.
163
Theory :
In the present work, except KPV-1, other Schiff bases are of HL type.
KPV-1 is of H2L type. Thus, the equilibria are,
L + H ↔ HL
and
L + H ↔ HL
H L + H ↔ H2L
In general, these equations can be represented as:
The thermodynamic proton-ligand stability constant (TKjH ) is given by:
[ ] 1
jHj
j
LHTK
LH H−
=
……….. (4.4.1)
TKjH is reciprocal of the thermodynamic dissociation constant of the acid LHj
dissociating as:
The overall thermodynamic proton-ligand stability constant βjH is given by:
[ ][ ]
jHj j
LHT
L Hβ
= ……….. (4.4.2)
and it refers to the reaction:
The stoichiometric proton-ligand stability constant is given by:
[ ] 1
jHj
j
LHK
LH H−
=
……….. (4.4.3)
and
[ ][ ]
jHj j
LH
L Hβ
= ……….. (4.4.4)
164
An inert electrolyte is used to determine the stability constant in a
particular salt medium. Sodium nitrate is mostly preferred as supporting
electrolyte, because of very slight complexing tendency of nitrate ion.
Generally, the competition between nitrate ion and the ligand under study is
minor importance. The molar concentrations are used in place of activities.
For the determination of dissociation constants, Bjerrum[52] introduced a
relation for the determination of Hn , which is defined as average number of
hydrogen bound to each ligand.
Hn = K1H [H] + 2K1
H K2H [H]2 + .....JK1
H K2H [H] ... Kj
H [H]j / 1 + K1H [H] + K1
H
K2H [H]2.....K1
HK2H.....Kj
H [H]j …….......(4.4.5)
From equation (4.4.4), we can write
[ ]
[ ]1
1
jHj
jH
jHj
j
j Hn
H
η
η
β
β
=
=
=∑
∑ : ( )0 1Hβ = ………… (4.4.6)
Equation (4.4.6) is called Bjerrum formation function of the system.
The determination of dissociation or formation constants from
experimental data comprises the following three steps: (i) evaluation of
formation curve of the system (ii) calculation of stoichiometric K`s of the
system by direct solution of the formation function and (iii) conversion of
stoichiometric constants into thermodynamic constants.
When the system consists of a ligand, which is a conjugated base of a
weak acid, the pH-metric method introduced by Bjerrum [52] has been widely
used. This method is known as "Bjerrum-Calvin pH titration technique".
In this technique, concentration of H+ ions is measured potentiometrically.
Thus, a large amount of data can be obtained in a short period of time. The
Irving and Rossotti method [53] has some advantages, such as:
(i) This method is valid for both pure water and for the mixed solvents.
(ii) In this method, it is not necessary to convert the pH-meter reading in to
stoichiometric hydrogen ion concentration.
165
(iii) It is not necessary to know the stoichiometric concentration of neutral
salt added to maintain the ionic strength constant.
Due to these advantages, this method is used in the present work.
In this method, the pH-meter is standardized using an aqueous buffer
and the meter reading B is plotted against volume of alkali used to titrate:
(1) A mixture containing a mineral acid, a chelating agent and a neutral
electrolyte to keep ionic strength constant.
(2) A mixture same as above but without the chelating agent.
The possible hydrolysis reactions are ignored because (i) fresh reagent
solutions were used in pH titrations, (ii) titration times were of the order of one
hour, (iii) there were no observable drifts with time in the meter readings and
(iv) the concentrations of the mineral acid or alkali in the solutions were small.
After each addition of standard alkali, the pH meter reading (B) is noted
using a glass electrode-saturated calomel electrode combination. For both the
titrations, same initial volume of the mixture and same standard alkali is used.
The titration curves obtained in the above two titrations are designated as the
reagent or ligand titration curve and the acid titration curve respectively.
Usually, a pH-meter calibrated with an aqueous buffer is used for
aqueous solutions only. However, for the mixed aqueous media, especially
aqueous dioxane solutions, Van Uitert and Haas[54] gave a relation between
the glass electrode reading B in dioxane-water medium and the stoichiometric
hydrogen ion concentration of the same in mixture of varied composition and
ionic strength. They reported the relation:
- log [H] = B + log f + log U0H ………. (4.4.7)
where f is the activity coefficient of the hydrogen ions in the solvent mixture
under consideration at the same temperature and ionic strength, and U0H is a
correction factor at zero ionic strength, which depends only on the solvent
composition and temperature. U0H is taken as unity in aqueous media. The
values of U0H and f are reported in literature[56]. The meter reading in any
aqueous dioxane solution can, therefore, be converted into hydrogen ion
166
concentration using equation (4.4.7), provided that correction factor for the
appropriate solvent, salt medium, and temperature, has been determined.
Equation (4.4.7) can be written as:
1/ antilog B = [H] f U0H ……. (4.4.8)
∴ [H] = 1/ f U0H . [1/antilog B] ……..... (4.4.9)
Substituting for [H] in equation (4.4.5) we get,
Hn = (K1H/f U0
H)[1/antilog B] +....+ ((JK1H K2
H...KJH) /(f U0
H)J)[1/antilogB]J
/(1+K1H/f U0
H))[1/antilog B]+..+ ((K1HK2
H...KJH)/(f U0
H)J)[1/antilogB] . . ..(4.4.10)
.H o Hj H kjK fU p= …....( 4.4.11)
[ ].H o Hj H jfU pβ = …. ……(4.4.12)
The proton-ligand constant, pKjH can be obtained by the following
methods:
1. Interpolation at half Hn values:
At the following Hn values, log K1 and log K2 can be determined:
( )1 0.5log HK n= . .... … (4.4.13)
( )2 1.5log HK n= ..……. (4.4.14)
2. Mid point slope method:
For H2L type ligands:
K1 K2 [L]2 = 1
or log K1 K2 = 2 pL1 ……. (4.4.15)
From the measured mid-point slope, D, the ratio K1/K2 can be
calculated by eq. (4.4.16):
1
2
4.606
2D
KK
−= +
……. (4.4.16)
The individual values of K1 and K2 were obtained by using K1/K2 values
and relation (4.4.15).
167
Results and discussion :
The titration curves obtained in the above two titrations are designated
as the acid titration curve and ligand or reagent titration curve respectively.
The titration curves for KPV-1 and KPV-4 are shown in Figure 4.41.
It is observed from these figures that for the same volume of alkali, the
reagent titration would show a lower pH than the acid titration.
From the acid titration curve and ligand titration curve, the average
number of proton associated with the ligand ( Hn ) can be calculated by the
equation given by Irving and Rossotti[54].
Hn = Y - (V” - V') (N0 + E0) / (V0 + V') T0L ……. (4.4.19)
where Y is number of displaceable protons per ligand molecule. For KPV-1, Y
is taken to be 2 whereas for rest of the Schiff bases its value is 1. V' and V”
values are the volume of alkali required at the same pH for both acid and
ligand titration curves respectively. V0 is the initial volume of test solution. N0,
E0 and T0L are the initial concentration of the alkali, acid and ligand
respectively.
Table 4.4.1 shows the values of Hn for all the Schiff bases. The
formation curves of the proton-ligand systems for all the bases are shown in
Figures 4.4.2 and 4.4.3. It is observed that for KPV-2 to KPV-7, the formation
curves extend from 0 to 1, whereas for KPV-1, Hn values extend over the
range from 0 to 2 indicating two dissociation steps.
For KPV-2 to KPV-7, the proton-ligand stability constants were obtained
by solving equation (4.4.1), which becomes equation (4.4.2):
( ) 111 0log
HH Hn n pK anti B
+ − = ……….(4.4.20)
The plots of log ( Hn )/( Hn -1) against B is a straight line and are shown
in Figure 4.4.4. From these plots, log pK1H values were calculated at several B
by the following equation
168
Figure 4.4.1: The plot of pH meter reading (B) against volume of NaOH for
(A) KPV - 1 and (B) KPV - 4 at 308.15 K.
0
5
10
15
0 1 2 3 4 5Vol. of NaOH added (ml)
BAcid
Acid +Ligand
0
5
10
15
0 1 2 3 4 5Vol. of NaOH added (ml)
B
Acid
Acid +Ligand
169
Table 4.4.1: The pH (B), Hn , log pK1H and other terms for Schiff bases at
308.15 K.
Half-integral value=log pk2
H= (B) Hn (1.5) = 4.23 Average log pK2H = 4.26
Half-integral value=log pK1H=(B) Hn (0.5)=12.07 Average log pK1
H =11.51
B V"-V' V' Hn
log [( Hn -1) / (2- Hn )]
*log [ Hn / (1- Hn )]
log pK2
H *log pK1
H
KPV – 1
3.8 0.559 0.704 1.4397 -0.1053 3.6947 3.9 0.530 0.711 1.4688 -0.0542 3.8458 4.0 0.521 0.719 1.4783 -0.0378 3.9622 4.1 0.509 0.727 1.4905 -0.0165 4.0835 4.2 0.501 0.734 1.4980 -0.0035 4.1965 4.3 0.486 0.749 1.5130 0.0226 4.3226 4.4 0.478 0.757 1.5213 0.0370 4.4370 4.5 0.468 0.772 1.5369 0.0642 4.5642 4.6 0.444 0.779 1.5558 0.0973 4.6973 4.7 0.428 0.795 1.5719 0.1258 4.8258
10.0 0.14 1.06 0.8609 *0.7916 *10.7916 10.1 0.15 1.07 0.8510 0.7567 10.8567 10.2 0.16 1.07 0.8411 0.7236 10.9236 10.3 0.17 1.07 0.8311 0.6921 10.9921 10.4 0.18 1.08 0.8212 0.6622 11.0622 10.5 0.18 1.09 0.8213 0.6623 11.1623 10.6 0.21 1.09 0.7915 0.5793 11.1793 10.7 0.22 1.11 0.7817 0.5539 11.2539 10.8 0.24 1.11 0.7618 0.5049 11.3049 10.9 0.25 1.12 0.7519 0.4816 11.3816 11.0 0.28 1.12 0.7222 0.4149 11.4149 11.1 0.31 1.16 0.6927 0.3530 11.4530 11.2 0.34 1.20 0.6633 0.2945 11.4945 11.3 0.36 1.22 0.6437 0.2568 11.5568 11.4 0.38 1.24 0.6241 0.2201 11.6201 11.5 0.40 1.25 0.6044 0.1840 11.6840 11.6 0.41 1.26 0.5946 0.1663 11.7663 11.7 0.43 1.28 0.5750 0.1313 11.8313 11.8 0.45 1.30 0.5554 0.0967 11.8967 11.9 0.47 1.32 0.5359 0.0625 11.9625 12.0 0.50 1.36 0.5068 0.0118 12.0118 12.1 0.51 1.38 0.4971 -0.0050 12.0950 12.2 0.52 1.50 0.4888 -0.0195 12.1805 12.3 0.54 1.54 0.4696 -0.0528 12.2472
170
Continue (Table 4.4.1)……...
B V"-V' V' Hn
log [ Hn / (1- Hn )] log pK1H
KPV – 2
9.8 0.250 1.05 0.7515 0.4807 10.2807
9.9 0.300 1.05 0.7018 0.3718 10.2718
10.0 0.340 1.06 0.6622 0.2922 10.2922
10.1 0.380 1.07 0.6225 0.2172 10.3172
10.2 0.430 1.07 0.5728 0.1274 10.3274
10.3 0.474 1.08 0.5292 0.0508 10.3508
10.4 0.520 1.08 0.4835 -0.0286 10.3714
10.5 0.560 1.09 0.4389 -0.1066 10.3934
10.6 0.630 1.09 0.3744 -0.2229 10.3771
10.7
10.8 0.670 0.720
1.09 1.10
0.3347 0.2853
-0.2983 -0.3989
10.4017 10.4011
10.9 0.760 1.11 0.2457 -0.4871 10.4129
11.0 0.800 1.12 0.2062 -0.5854 10.4146
11.1 0.850 1.13 0.1568 -0.7305 10.3695
11.2 0.900 1.14 0.1074 -0.9195 10.2805
Half-integral value=log pK1H = (B) Hn (0.5)=10.36 Average log pK1
H = 10.35
171
Continue (Table 4.4.1)……...
B V"-V' V' Hn
log [ Hn / (1- Hn )] log pK1
H
KPV - 3
11.0 0.160 1.210 0.8416 0.7253 11.7253
11.1 0.175 1.220 0.8268 0.6788 11.7788
11.2 0.195 1.230 0.8070 0.6214 11.8214
11.3 0.210 1.235 0.7922 0.5812 11.8812
11.4 0.225 1.240 0.7774 0.5431 11.9431
11.5 0.250 1.250 0.7527 0.4835 11.9835
11.6 0.280 1.260 0.7231 0.4169 12.0169
11.7 0.300 1.270 0.7034 0.3751 12.0751
11.8 0.320 1.280 0.6837 0.3348 12.1348
11.9 0.350 1.290 0.6542 0.2768 12.1768
12.0 0.370 1.300 0.6345 0.2395 12.2395
12.1 0.390 1.310 0.6148 0.2031 12.3031
12.2 0.440 1.330 0.5656 0.1147 12.3147
12.3 0.480 1.350 0.5264 0.0459 12.3459
12.4 0.540 1.360 0.4673 -0.0569 12.3431
12.5 0.560 1.400 0.4481 -0.0905 12.4095
Half-integral value=log pK1H=(B) Hn (0.5)=12.34 Average log pK1
H=12.09
172
Continue (Table 4.4.1)……...
B V"-V' V' Hn
log [ Hn / (1- Hn )] log pK1
H
KPV – 4
11.0 0.260 1.120 0.7420 0.4588 11.4588
11.1 0.290 1.120 0.7123 0.3936 11.4936
11.2 0.320 1.120 0.6825 0.3323 11.5323
11.3 0.355 1.120 0.6478 0.2646 11.5646
11.4 0.380 1.140 0.6231 0.2184 11.6184
11.5 0.400 1.149 0.6034 0.1822 11.6822
11.6 0.440 1.160 0.5638 0.1115 11.7115
11.7 0.477 1.170 0.5273 0.0474 11.7474
11.8 0.520 1.180 0.4848 -0.0264 11.7736
11.9 0.567 1.188 0.4383 -0.1077 11.7923
12.0 0.600 1.200 0.4058 -0.1656 11.8344
12.1
12.2 0.645 0.690
1.213 1.230
0.3615 0.3172
-0.2471 -0.3330
11.8529 11.8670
12.3 0.728 1.257 0.2801 -0.4100 11.8900
12.4 0.770 1.270 0.2388 -0.5035 11.8965
Half-integral value=log pK1H=(B) Hn (0.5)=11.77 Average log pK1
H=11.71
173
Continue (Table 4.4.1)……...
B V"-V' V' Hn
log [ Hn / (1- Hn )] log pK1
H
KPV - 5
11.5 0.239 1.249 0.7636 0.5092 12.0092
11.6 0.250 1.270 0.7528 0.4836 12.0836
11.7 0.260 1.360 0.7346 0.4422 12.1422
11.8 0.350 1.380 0.6549 0.2782 12.0782
11.9 0.391 1.410 0.6157 0.2047 12.1047
12.0 0.410 1.420 0.5961 0.1690 12.1690
12.1 0.440 1.422 0.5667 0.1166 12.2165
12.2 0.450 1.440 0.5569 .0992 12.2992
12.3 0.490 1.500 0.5182 .0316 12.3316
12.4 0.530 1.590 0.4801 -0.0345 12.3654
12.5 0.564 1.656 0.4476 -0.0914 12.4086
Half-integral value=log pK1H=(B) Hn (0.5)=12.35 Average log pK1
H =12.20
174
Continue (Table 4.4.1)……...
Half-integral value=log pK1H=(B) Hn (0.5)=12.20 Average log pK1
H=11.86
B V"-V' V' Hn
log [ Hn / (1- Hn )] log pK1
H
KPV - 6
11.0 0.400 1.180 0.6037 0.1828 11.1828
11.1 0.410 1.200 0.5940 0.1652 11.2652
11.2 0.420 1.210 0.5842 0.1476 11.3476
11.3 0.425 1.220 0.5793 0.1390 11.4390
11.4 0.435 1.240 0.5696 0.1218 11.5218
11.5 0.440 1.250 0.5648 0.1132 11.6132
11.6 0.450 1.280 0.5552 0.0963 11.6963
11.7 0.470 1.300 0.5357 0.0621 11.7621
11.8 0.480 1.340 0.5263 0.0457 11.8457
11.9 0.485 1.390 0.5219 0.0381 11.9381
12.0 0.490 1.500 0.5183 0.0317 12.0317
12.1 0.495 1.530 0.5137 0.0238 12.1238
12.2 0.510 1.550 0.4992 -0.0014 12.1986
12.3 0.520 1.580 0.4898 -0.0178 12.2822
12.4 0.550 1.600 0.4606 -0.0686 12.3314
12.5 0.560 1.640 0.4513 -0.0849 12.4151
175
Continue (Table 4.4.1)……...
B V"-V' V' Hn
log [ Hn / (1- Hn )] log pK1
H
KPV - 7
11.0 0.218 1.160 0.7839 0.5596 11.5596
11.1 0.226 1.180 0.7761 0.5398 11.6398
11.2 0.270 1.200 0.7326 0.4378 11.6378
11.3 0.290 1.224 0.7130 0.3952 11.6952
11.4 0.320 1.250 0.6835 0.3343 11.7343
11.5 0.350 1.276 0.6540 0.2766 11.7766
11.6 0.380 1.300 0.6246 0.2211 11.8211
11.7 0.410 1.390 0.5958 0.1686 11.8686
11.8 0.450 1.380 0.5563 0.0982 11.8982
11.9 0.480 1.434 0.5273 0.0476 11.9476
12.0 0.500 1.480 0.5082 0.0142 12.0142
12.1 0.530 1.533 0.4794 -0.0359 12.0641
12.2 0.560 1.580 0.4505 -0.0863 12.1137
Half-integral value=log pK1H=(B) Hn (0.5)=12.05 Average log pK1
H=11.83
176
Figure 4.4.2 : The plot of Hn against B for Schiff bases at 308.15 K.
0
0.5
1
9 10 11 12 13B
n H
KPV - 2
KPV - 3
KPV - 4
0
0.5
1
10 11 12 13B
n H
KPV - 5
KPV - 6
KPV - 7
178
Figure 4.4.4 : The plot of log [ Hn /(1- Hn )]against B for Schiff bases at 308.15
K.
-1.5
-1
-0.5
0
0.5
1
1.5
2
9 10 11 12 13B
log[
n H/(1
-nH)]
KPV - 2
KPV - 3
-0.5
0
0.5
1
10 11 12 13
B
log
[nH/(1
-nH)]
KPV - 5
KPV - 6
179
Figure 4.4.5 : The plot of log [ Hn -1/(2- Hn )]against B for KPV-1 at 308.15
K.
-1.5
-1
-0.5
0
0.5
1
1.5
9 10 11 12 13B
log
[nH
-1/(2
-nH)]
180
( )( )1log log
1HH
H
npK B
n
= +
− ………. (4.4.21)
From these log pK1H values, the average value of pK1
H can be
calculated.
For KPV-1 base, the proton-ligand constants were calculated by
solving equation (4.4.1). For all the points below Hn =1, the following equation
was used. ( )( )1log log
1HH
H
npK B
n
= +
− ………. (4.4.22)
where as for all the points above Hn =1, the equation used was:
( )( )2
1log log
2HH
H
npK B
n
− = +
− ………. (4.4.23)
The plot of log ( )( )
1
2
nH
nH
−
−
against B gives a straight line and are
shown in Figure 4.4.5. The values of log pK1H and log pK2
H are given in Table
4.4.1
The dissociation constants of all the Schiff bases were also evaluated
by half-integral method. All these values are given in Table 4.4.1. It is
observed that the values calculated by half-integral are in fairly good
agreement with the observed values.
The comparison of pK1H values shows that acidic character changes in
the order: KPV-2 > KPV-4 > KPV-7 > KPV-6 > KPV-3 ≈ KPV-5. The acidic
character depends on the type of substituent group. In KPV-2, -Cl is at ortho
position whereas in KPV-7, it is at para position. Similarly, KPV-4 and KPV-5
contain –NO2 group at ortho and para positions. Thus, it is observed that
presence of –Cl or –NO2 group at ortho position increases the acidic character
whereas at para position, the acidic character is found to decrease. The
presence of intra molecular hydrogen bonding also plays an important role in
deciding the acidic character of a compound. When intra molecular hydrogen
bonding is weak, acidic character increases. In KPV-2 and KPV-4, due to
ortho substitution, there may be some steric hindrance, which may cause
181
some weakening in intra molecular interactions thereby increasing the acidic
character. In case of KPV-1, due to –OH group at ortho position, acidic
character is increased but not as much as KPV-2 and KPV-4.
182
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185
In this chapter, various acoustical parameters have been evaluated from
experimental data of Ultrasonic velocity, density and viscosity of solutions of
some Schiff bases in dimethylformamide (DMF) and dimethylsulfoxide
(DMSO) at 308.15 K.
Introduction :
The name Ultrasound is given to sound waves having frequencies
higher than those to which the human ear can respond (i.e.> 20 KHz ). It is
also known as silent sound waves.
In recent years, Ultrasonic has become the subject of extensive
research in wide range of application in different fields like chemical
industries, consumer industries, medical field, process industries, food
industry, physics, chemistry and biology etc [1-13]. As it is a non-destructive
technique, it attracts more attention. In medical field, this technique has been
used to detect gall stones, cancerous tissues, and foreign bodies in tissues.
Further ultrasonic studies on hemoglobin, myoglobin and borine serum
albumin have been reported [8-10]. In chemistry, ultrasonic waves are knows to
be useful to chemical reactions and processes. Ultrasound waves have
proven to enhance reaction yields in more convenient reaction conditions[14-17].
Further, it helps to understand the molecular interactions in liquid[18]. liquid
mixtures[19-25] and solutions[26-33]. Various thermodynamic properties can be
also studied by measuring acoustical parameters in liquid mixtures and
solutions.
Literature survey shows that much work has been done in pure
liquids[34-36], liquid mixtures[37-48] and solutions of inorganic salts[49-52], amino
acid[53-56], polymers[57-60 ] etc.
However scanty work has been done for organic compounds [61-65]
specially Schiff bases [66-69].
Thus, in the present chapter, acoustical properties of solutions of some
Schiff bases have been studied in DMF and DMSO at 308.15 K.
186
Experimental :
The solvents dimethyl formamide (DMF) and dimethylsulfoxide
(DMSO), used in the present study are purified by standard methods. The
mole fraction of purity was better than 0.995 for both the solvents.
The solutions of all the Schiff bases were prepared in both the solvents
over the wide range of concentrations. The densities, viscosities and
ultrasonic velocities of pure solvents and solutions of different concentration
were measured at 308.15 K by using pyknometer, an Ubbelohde suspended
level viscometer and ultrasonic interferometer operating at 2 MHz with the
uncertainties of 0.0001 g/cm3, + 0.06 % and 0.01% respectively.
Density measurement :
The weight of distilled water, pure solvents and solutions of Schiff
bases were measured by using pyknometer. The densities were evaluated by
using following equation :
ρ (g/cc)=[(wt. of solvent or solution)/(wt. of water)] x [density of water].. (4.5.1)
Viscosity measurement :
To determine viscosity of solution the determine the Ubbeholde
viscometer [70] was used, which obeys Stoke’s low[71]. The measured quantity
of the distilled water / solvent / solution was placed in the viscometer, which
was suspended in a thermostat at 308.15 + 0.1 K. The digital stopwatch with
an accuracy of + 0.01 sec was used to determine flow time of solutions. Using
the flow times (t) and known viscosity of standard water sample the viscosity
of solvent and solution were determined according to equation:
η1 / η2 = t1ρ1 / t2ρ2 ……….(4.5.2)
Sound velocity measurement :
Ultrasonic interferometer (Model No. F-81), Mittal Enterprise, New
Delhi, working at frequency of 2 MHz was used to determine sound velocity.
187
The solvent / solution was filled in the measuring cell with quartz crystal
and then micrometer was fixed. The circulation of water from the thermostat
maintained at 308.15 K was started and test solvent /solution in the cell is
allowed to thermally equilibrate. The micrometer was rotated very slowly so as
to obtain a maximum or minimum of anode current (n). A number of maximum
readings of anode current were counted.
The total distance (d) traveled by the micrometer for n=10, was read.
The wavelength (λ) was determined according to the equation (4.5.3).
λ = 2d / n ………. (4.5.3)
The sound velocity (U) of solvent and solutions were calculated from the
wavelength and frequency (F) according to equation (4.5.4).
U = λ F ………. (4.5.4)
188
Results and Discussion :
The density (ρ), viscosity (η) and sound velocity (U) of pure solvents
and different Schiff bases solutions in dimethylformamide (DMF) and
dimethylsulfoxide (DMSO) were calculated at 308.15 K and are reported in
Table 4.5.1.
From these measurements, various acoustical parameters like specific
acoustical impendence (Z), isentropic compressibility (κs), intermolecular free
length (Lf), Rao’s molar sound function (Rm), molar compressibility (W),
Vander Waals constant (b), relaxation strength (r), internal pressure (π),
solvation number (Sn) etc. were evaluated using the following equations:
1. Specific acoustical impedance :
Specific acoustical impedance (Z) can be calculated as:
Z = Uρ ………. (4.5.5)
2. Isentropic compressibility :
Isentropic compressibility (κs) can be evaluated according to the
following the equation [72].
κs = 1/U2ρ ………. (4.5.6)
3. Intermolecular free path length :
Jacobson [73] proposed an equation for calculating the inter molecular
free path length (Lf), which is given below:
Lf = KJ κs 1/2 ………. (4.5.7)
where KJ is Jacobson constant (=6.0816 x 104)
4. Rao’s molar sound function :
Rao’s molar sound function (Rm) can be evaluated by an equation
given by Bagchi et al [74].
Rm = (M/ρ) U1/3 ………. (4.5.8)
189
Table 4.5.1: The density (ρ), ultrasonic velocity (U) and viscosity (η) of Schiff
bases in DMF and DMSO at 308.15 K.
Conc. (M)
Density ρ
(gm.cm-3)
VelocityU . 10-5 (cm.s-1)
Viscosityη . 103
(poise)
Density ρ
(gm.cm-3)
Velocity U . 10-5 (cm.s-1)
Viscosityη . 103 (poise)
DMF DMSO
KPV - 1 KPV - 1
0.00 0.9356 1.4380 0.6780 1.0853 1.4648 0.9425 0.01 0.9366 1.4468 0.6940 1.0879 1.5156 1.6036 0.02 0.9378 1.4492 0.7013 1.0886 1.4940 1.6696 0.04 0.9386 1.4536 0.7215 1.0889 1.4884 1.6945 0.06 0.9396 1.4588 0.7431 1.0892 1.4874 1.7079 0.08 0.9405 1.4616 0.7490 1.0896 1.4820 1.7349 0.10 0.9413 1.4648 0.7674 1.0899 1.4816 1.7510
KPV - 2 KPV - 2
0.01 0.9382 1.4476 0.6857 1.0887 1.4684 1.3822 0.02 0.9388 1.4424 0.6893 1.0890 1.4656 1.4325 0.04 0.9401 1.4400 0.7211 1.0893 1.4632 1.4770 0.06 0.9411 1.4388 0.7277 1.0899 1.4608 1.5167 0.08 0.9413 1.4364 0.7388 1.0901 1.4596 1.5682 0.10 0.9416 1.4336 0.7539 1.0912 1.4584 1.6263
KPV - 3 KPV - 3
0.01 0.9380 1.4432 0.6828 1.0907 1.4800 1.6506 0.02 0.9404 1.4492 0.7108 1.0909 1.4780 1.6884 0.04 0.9429 1.4556 0.7401 1.0922 1.4744 1.7123 0.06 0.9444 1.4580 0.7605 1.0926 1.4720 1.7331 0.08 0.9452 1.4624 0.7825 1.0960 1.4704 1.7605 0.10 0.9472 1.4680 0.8143 1.0971 1.4688 1.8940
KPV - 4 KPV - 4
0.01 0.9408 1.4780 0.7170 1.0926 1.4904 1.7389 0.02 0.9414 1.4644 0.7236 1.0930 1.4872 1.7551 0.04 0.9433 1.4600 0.7360 1.0937 1.4848 1.7844 0.06 0.9441 1.4592 0.7499 1.0945 1.4820 1.8061 0.08 0.9446 1.4576 0.7556 1.0963 1.4744 1.8760 0.10 0.9459 1.4524 0.7671 1.0976 1.4708 1.9278
190
Continue…. (Table: 4.5.1)
Conc. (M)
Density ρ
(gm.cm-3)
VelocityU . 10-5
(cm.s-1)
Viscosityη . 103 (poise)
Density ρ
(gm.cm-3)
Velocity U . 10-5 (cm.s-1)
Viscosityη . 103 (poise)
DMF DMSO
KPV - 5 KPV - 5
0.01 0.9382 1.4344 0.6795 1.0925 1.4384 1.7503 0.02 0.9403 1.4372 0.6949 1.0937 1.4516 1.8064 0.04 0.9412 1.4404 0.6970 1.0942 1.4600 1.8429 0.06 0.9422 1.4472 0.7094 1.0944 1.4716 1.8901 0.08 0.9444 1.4496 0.7367 1.0953 1.4784 2.0244 0.10 0.9482 1.4544 0.7634 1.0953 1.4840 2.0701
KPV - 6 KPV - 6
0.01 0.9412 1.4480 0.7224 1.0940 1.4692 2.0726 0.02 0.9414 1.4500 0.7315 1.0946 1.4616 2.0724 0.04 0.9430 1.4528 0.7478 1.0949 1.4516 2.0601 0.06 0.9438 1.4544 0.7664 1.0956 1.4460 1.9979 0.08 0.9453 1.4556 0.7908 1.0969 1.4364 1.9229 0.10 0.9459 1.4592 0.8103 1.0971 1.4284 1.8789
KPV - 7 KPV - 7
0.01 0.9373 1.4712 0.7622 1.0918 1.5040 1.6592 0.02 0.9397 1.4700 0.7724 1.0922 1.4952 1.7913 0.04 0.9431 1.4664 0.7829 1.0924 1.4912 1.8488 0.06 0.9441 1.4640 0.7954 1.0925 1.4808 1.9757 0.08 0.9479 1.4624 0.8724 1.0927 1.4692 2.0243 0.10 0.9498 1.4568 0.9667 1.0929 1.4484 2.2283
KPV - 8 KPV - 8
0.01 0.9439 1.4788 0.9987 1.0928 1.5148 1.8429 0.02 0.9446 1.4728 1.0339 1.0935 1.5112 1.9183 0.04 0.9457 1.4688 1.1051 1.0954 1.5008 1.9434 0.06 0.9476 1.4640 1.1893 1.0957 1.4912 2.0736 0.08 0.9480 1.4628 1.2796 1.0962 1.4828 2.1239 0.10 0.9487 1.4540 1.3809 1.0965 1.4748 2.7090
191
The apparent molecular weight (M) of the solution can be calculated
according to equation (4.5.9) :
M = M1W1 + M2W2 ………. (4.5.9)
where W1 and W2 are weight fractions of solvent and solute respectively. M1 and
M2 are the molecular weights of the solvent and compounds respectively.
5. Molar compressibility :
Molar compressibility (W) can be calculated by the following equation[75].
W = (M/ρ) κs -1/7 ………. (4.5.10)
6. Van der Waals Constant :
Van der Waals constant (b) can be calculated as follows [76].
b = M/ρ 1- (RT/MU2) √ [1 +(MU2/ 3RT) – 1] ………. (4.5.11)
where R is the gas constant (=8.3143 JK-1 mol-1) and T is the absolute
temperature.
7. Relaxation Strength :
The relaxation strength (r) can be calculated as follows [77].
r = 1- [U/U∞] 2 ………. (4.5.12)
where U∞ = 1.6 x 105 cm/s.
8. Internal Pressure :
Suryanarayana and Kuppuswamy[78] gave the following equation for
evaluating internal pressure:
π = bRT [Kη/U] 1/2 ρ2/3/M7/6 ………. (4.5.13)
192
where b is the packing factor (= 2). K is a constant (=4.28 X 109). The internal
pressure (π) depends on temperature, density, ultrasonic velocity and specific
heat at constant pressure.
9. Solvation Number :
The solvation number (Sn) can be evaluated according to Passynsky[79]
method.
Sn = M2 / M1 [1-κs /κs 1] [(100-X)/X] ……… (4.5.14)
where X is the number of grams of solute in 100 g. of the solution and M1 and M2
are the molecular weights of solvent and solute respectively. κs1 and κs are the
isentropic compressibility of solvent and solution, respectively.
These acoustical parameters are useful for the understanding of molecular
interactions in a solution. Some of these parameters are given in Tables 4.5.2
and 4.5.3 for Schiff bases in DMF and DMSO at 308.15 K.
Further, some of these parameters were also correlated with
concentration. The correlation coefficients along with correlation equation for
these parameters are given in Tables 4.5.4 and 4.5.5 for all the Schiff bases in
both the solvents.
Fig. 4.5.1 and Fig. 4.5.2 shows the variation of ultrasonic velocity with
concentration for Schiff bases solutions in DMF and DMSO. It is observed from
these figures that in DMF, ultrasonic velocity (U) increases with concentration for
KPV-1, KPV-3, KPV- 5 and KPV- 6 and decreases for KPV-2, KPV-4, KPV-7 and
KPV-8 where as in DMSO, velocity is found to decrease with increase in
concentration for all Schiff bases except KPV- 5.
The ultrasonic velocity depends on intermolecular free path length (Lf).
The ultrasonic velocity U increases with decrease in intermolecular free path
length (Lf) and vice versa. The variation of intermolecular free length (Lf) against
concentration is shown in Fig. 4.5.3 and 4.5.4 for Schiff base solutions in both the
solvents. It is obvious that in DMF, Lf decreases for KPV-1, KPV-3, KPV-5 and
193
KPV-6 where as it increases for KPV-2, KPV-4, KPV-7 and KPV-8. This is
reverse of Fig. 4.5.1 and 4.5.2 as expected. Similarly, Lf is found to increase with
concentration in DMSO for all Schiff bases except KPV-5. The increase in
ultrasonic velocity and decrease in Lf indicates close association between solute
and solvent molecules. Where as decrease in velocity and increase in Lf suggest
predominance of solute –solute interactions.
The predominance of a particular interaction in a particular solution can
also be decided by isentropic compressibility, which is shown in Fig. 4.5.5 and
4.5.6 for all the bases in DMF and DMSO respectively. It is observed that in DMF
solution, isentropic compressibility decreases with increase in concentration for
KPV-1, KPV-3, KPV-5 and KPV-6. However, it decreases only for KPV-5 in
DMSO. It is observed from Table 4.5.2 that in DMF solutions, relaxation strength
(r) also decreases with increase in concentration for KPV-1, KPV-3, KPV-5 and
KPV-6 where as it increases for KPV-2, KPV-4 KPV-7 and KPV-8. However,
acoustic impedance (Z) shows reverse nature. In DMSO solutions (Table 4.5.3),
only for KPV-5, Z increases and r decreases with concentration. For all other
Schiff bases, Z decreased and relaxation strength (r) increased with
concentration. The increase in Z and decrease in κs and r again proves the
existence of solute-solvent[80] interactions in KPV-1, KPV-3, KPV-5 AND KPV-6
(in DMF) and KPV-5 (in DMSO). The increase in isentropic compressibility (κs)
and relaxation strength (r) in other Schiff bases, KPV-2, KPV-4, KPV-7, KPV-8 in
DMF and all other bases except KPV-5 in DMSO suggests the predominance of
solute-solute interactions.
It is obvious from Tables 4.5.4 and 4.5.5 that Rao’s molar function (Rm),
molar compressibility (W) and Vander Waal’s constant (b) vary linearly with
concentration for all the Schiff bases in both the solvents. This suggests the
absence of complex formation in these solutions.
The internal pressure (π) is the resultant of the forces of attraction and
repulsion between the molecules in a liquid. It is observed from the Tables 4.5.2
that in DMF, except for KPV-1 and KPV-2, π values are first increasing and then
194
decreasing. For KPV-3, KPV-6, KPV-7 and KPV-8, it increased continuously. For
KPV-4, it decreases continuously whereas for KPV-5, π values first decreased
and then increased. In DMSO, except KPV-6, for other bases, internal pressure
values are found to increase. The increase in π values indicate the solute-solvent
interactions. Thus, it is observed that in these systems, both solute-solute and
solute-solvent interactions exist although some acoustical properties suggest the
predominance of one type of interaction.This is again confirmed by solvation
number (Sn).
The solvation number (Sn) is a measure of structure forming or structure
breaking tendency of solute in a solution. The increase in Sn values indicates
the structure-forming tendency of solute or vice versa. Fig.4.5.7 and 4.5.8
shows the variation of Sn with concentration in both DMF and DMSO
respectively. It is observed that in both DMF and DMSO solutions, except KPV-
6, other bases show structure-forming tendency. The Sn decreases with
concentration in both DMF and DMSO for KPV-6, suggesting thereby structure-
breaking tendency of this Schiff base.
Overall, both solute-solute and solute-solvent interactions exist in these
solutions of Schiff bases in both the solutions.
195
Table 4.5.2: Variation of acoustical parameters with concentration of Schiff bases in DMF at 308.15 K.
Conc. (M)
Specific Impedance
Z.10 -5 (gm.cm-2)
RelaxationStrength
r
Rao’s molar Sound Function
Rm.10-3 (cm-8/3.sec-1/3)
Molar Compressibility
W.10-3 (cm-1.dyn-1)
Van der Waal’sconstant
b (cm3.mol-1)
Internal Pressure
π
KPV - 1 0.00 1.3454 0.1922 4.0934 2.3033 73.4366 465.60060.01 1.3551 0.1823 4.1152 2.3152 73.7088 467.58560.02 1.3591 0.1796 4.1300 2.3238 73.9475 467.67800.04 1.3643 0.1746 4.1663 2.3442 74.5490 469.21170.06 1.3707 0.1687 4.2024 2.3644 75.1341 470.96710.08 1.3746 0.1655 4.2366 2.3838 75.7191 468.05150.10 1.3788 0.1619 4.2715 2.4035 76.3113 468.9551
KPV - 2 0.01 1.3581 0.1814 4.1130 2.3145 73.6596 464.64990.02 1.3541 0.1873 4.1273 2.3231 74.0008 464.02330.04 1.3537 0.1900 4.1628 2.3438 74.6924 469.64900.06 1.3541 0.1913 4.2006 2.3655 75.4079 466.62230.08 1.3521 0.1940 4.2408 2.3884 76.1846 465.03290.10 1.3499 0.1972 4.2800 2.4108 76.9509 464.7559
KPV - 3 0.01 1.3537 0.1864 4.1087 2.3123 73.6456 464.43700.02 1.3628 0.1796 4.1246 2.3217 73.8536 470.91550.04 1.3725 0.1724 4.1611 2.3426 74.4316 474.74010.06 1.3769 0.1696 4.1998 2.3637 75.1073 475.84610.08 1.3823 0.1646 4.2399 2.3873 75.7766 476.74900.10 1.3905 0.1582 4.2771 2.4085 76.3778 480.7038
KPV - 4 0.01 1.3905 0.1467 4.1326 2.3241 73.5763 470.75620.02 1.3786 0.1623 4.1416 2.3305 73.9414 472.06410.04 1.3772 0.1673 4.1775 2.3517 74.6676 470.98330.06 1.3776 0.1683 4.2215 2.3768 75.4873 469.48480.08 1.3768 0.1701 4.2660 2.4021 76.3276 465.47940.10 1.3738 0.1760 4.3029 2.4238 77.0879 464.1697
196
Continue…. DMF
Conc. (M)
Specific Impedance
Z.10 -5 (gm.cm-2)
RelaxationStrength
r
Rao’s molar Sound Function
Rm.10-3 (cm-8/3.sec-1/3)
Molar Compressibility
W.10-3 (cm-1.dyn-1)
Van der Waal’sconstant
b (cm3.mol-1)
Internal Pressure
π
KPV - 5 0.01 1.3458 0.1963 4.1030 2.3099 73.6723 464.34990.02 1.3514 0.1931 4.1207 2.3204 73.9604 466.59390.04 1.3557 0.1895 4.1682 2.3472 74.7883 460.74750.06 1.3636 0.1819 4.2187 2.3755 75.6143 457.86190.08 1.3690 0.1792 4.2591 2.3988 76.3240 460.81260.10 1.3791 0.1737 4.2939 2.4194 76.8954 463.5474
KPV - 6 0.01 1.3629 0.1810 4.0911 2.3032 73.2572 479.13330.02 1.3650 0.1787 4.1047 2.3108 73.4789 480.14570.04 1.3700 0.1755 4.1256 2.3229 73.8234 482.06840.06 1.3727 0.1737 4.1488 2.3361 74.2263 484.60110.08 1.3760 0.1724 4.1684 2.3476 74.5703 489.11410.10 1.3803 0.1683 4.1943 2.3621 74.9912 491.2657
KPV - 7 0.01 1.3790 0.1545 4.1392 2.3271 73.7896 485.62000.02 1.3814 0.1559 4.1494 2.3338 73.9983 486.86950.04 1.3830 0.1600 4.1745 2.3494 74.5164 486.01200.06 1.3822 0.1628 4.2112 2.3706 75.2249 484.71480.08 1.3862 0.1646 4.2353 2.3857 75.6985 503.32860.10 1.3837 0.1710 4.2639 2.4029 76.3123 525.3829
KPV - 8 0.01 1.3958 0.1458 4.1200 2.3181 73.3397 556.64140.02 1.3912 0.1527 4.1358 2.3277 73.7178 563.89090.04 1.3890 0.1573 4.1760 2.3510 74.5139 576.26450.06 1.3873 0.1628 4.2115 2.3720 75.2381 591.56450.08 1.3867 0.1641 4.2571 2.3979 76.0908 605.87500.10 1.3794 0.1742 4.2936 2.4195 76.8969 623.3630
197
Table 4.5.3: Variation of acoustical parameters with concentration of Schiff bases in DMSO at 308.15 K.
Conc. (M)
Specific Impedance
Z.10 -5 (gm.cm-2)
RelaxationStrength
r
Rao’s molar Sound Function
Rm.10-3 (cm-8/3.sec-1/3)
Molar Compressibility
W.10-3 (cm-1.dyn-1)
Van der Waal’sconstant
b (cm3.mol-1)
Internal Pressure
π
KPV - 1 0.00 1.5863 0.1655 3.7921 2.1778 67.8284 556.23250.01 1.6253 0.1281 3.8237 2.1944 68.0190 715.96840.02 1.6220 0.1328 3.8306 2.1988 68.1625 728.98040.04 1.6203 0.1346 3.8550 2.2130 68.6036 723.68750.06 1.6196 0.1358 3.8790 2.2269 69.0510 723.78750.08 1.6142 0.1421 3.8989 2.2388 69.4813 722.50180.10 1.6148 0.1425 3.9216 2.2520 69.9290 723.1596
KPV - 2 0.01 1.5986 0.1577 3.8019 2.1839 67.9215 670.19510.02 1.5960 0.1609 3.8143 2.1913 68.1860 679.73960.04 1.5939 0.1637 3.8427 2.2079 68.7405 684.28520.06 1.5921 0.1664 3.8700 2.2239 69.2748 687.65540.08 1.5911 0.1678 3.8998 2.2412 69.8371 693.02900.10 1.5914 0.1692 3.9261 2.2567 70.3385 699.9337
KPV - 3 0.01 1.6142 0.1444 3.8041 2.1849 67.8085 730.55970.02 1.6124 0.1467 3.8168 2.1924 68.0665 736.05700.04 1.6103 0.1508 3.8391 2.2059 68.5255 735.99630.06 1.6083 0.1536 3.8656 2.2214 69.0430 734.53190.08 1.6116 0.1554 3.8817 2.2317 69.3650 735.68370.10 1.6114 0.1573 3.9060 2.2461 69.8336 757.2291
KPV - 4 0.01 1.6284 0.1323 3.8090 2.1875 67.7602 747.50120.02 1.6255 0.1360 3.8225 2.1956 68.0497 747.91920.04 1.6239 0.1388 3.8531 2.2136 68.6423 747.05000.06 1.6220 0.1421 3.8830 2.2312 69.2260 744.72250.08 1.6164 0.1508 3.9047 2.2448 69.7311 753.86740.10 1.6144 0.1550 3.9316 2.2609 70.2748 757.8773
198
Continue…. DMSO Conc.
(M) Specific
Impedance Z.10 -5
(gm.cm-2)
RelaxationStrength
r
Rao’s molar Sound Function
Rm.10-3 (cm-8/3.sec-1/3)
Molar Compressibility
W.10-3 (cm-1.dyn-1)
Van der Waal’sconstant
b (cm3.mol-1)
Internal Pressure
π
KPV - 5 0.01 1.5715 0.1918 3.7645 2.1656 67.6502 763.34150.02 1.5876 0.1769 3.7893 2.1793 67.9263 768.36870.04 1.5975 0.1673 3.8298 2.2021 68.5549 765.84960.06 1.6105 0.1541 3.8742 2.2269 69.2092 764.48480.08 1.6193 0.1462 3.9120 2.2483 69.8061 781.55970.10 1.6254 0.1397 3.9520 2.2709 70.4590 780.6788
KPV - 6 0.01 1.6073 0.1568 4.0911 2.1713 67.4706 824.83030.02 1.5999 0.1655 4.1047 2.1722 67.5811 824.93400.04 1.5894 0.1769 4.1256 2.1778 67.8687 820.90420.06 1.5842 0.1832 4.1488 2.1844 68.1404 805.90350.08 1.5756 0.1940 4.1684 2.1882 68.3638 789.56840.10 1.5671 0.2030 4.1943 2.1946 68.6598 778.5227
KPV - 7 0.01 1.6421 0.1164 4.1392 2.1935 67.8057 726.92840.02 1.6331 0.1267 4.1494 2.1983 68.0498 754.05160.04 1.6290 0.1314 4.1745 2.2144 68.6044 759.84800.06 1.6178 0.1434 4.2112 2.2279 69.1508 780.81410.08 1.6054 0.1568 4.2353 2.2406 69.6873 786.12000.10 1.5830 0.1805 4.2639 2.2491 70.2014 823.0397
KPV - 8 0.01 1.6554 0.1037 4.1200 2.1975 67.8036 763.36850.02 1.6525 0.1079 4.1358 2.2050 68.0769 775.84290.04 1.6440 0.1202 4.1760 2.2178 68.5823 776.09590.06 1.6339 0.1314 4.2115 2.2336 69.1887 795.83620.08 1.6254 0.1411 4.2571 2.2494 69.7836 799.45050.10 1.6171 0.1504 4.2936 2.2657 70.3913 896.0518
199
Fig. 4.5.1 : Variation of ultrasonic velocity (U) against concentration for Schiff
bases in DMF at 308.15 K.
1.42
1.46
1.5
0 0.04 0.08 0.12
Concentration (M)
Vel
ocity
.10-5
(cm
/sec
)
KPV - 5KPV - 6KPV - 7KPV - 8
200
Fig. 4.5.2 : Variation of ultrasonic velocity (U) against concentration for
Schiff bases in DMSO at 308.15 K.
201
Table 4.5.4 : The correlation coefficient (γ) and correlation equations
between some acoustical parameters and concentrations (C)
of Schiff bases in DMF solutions at 308.15 K.
Parameters γ Correlation equation
KPV-1
U (cm.sec-1) 0.9946 U – 20285 C = 144532
W (cm-1.dyn-1) 0.9998 W – 988.26 C = 2304.8
b (cm3.mol-1) 0.9998 b - 29.17 C = 73.388
Rm (cm-8/3.sec-1/3) 0.9999 Rm -1752.9 C = 4096.5
η (poise) 0.9911 η + 8.20E-3 C = 6.90E-3
r 0.9947 r + 0.2307 C = 0.184
KPV-2
U (cm .sec-1) 0.9582 U + 13381 C = 141671
W (cm-1.dyn-1) 0.9995 W – 1078.4 C = 2302.0
b (cm3.mol-1) 0.9993 b – 36.549 C = 73.261
Rm (cm-8/3.sec-1/3) 0.9992 Rm -1872.2 C = 4119.8
η (poise) 0.9772 η - 7.60E-3 C = 6.80E-3
r 0.9578 r - 0.1505 C = 0.1824
KPV-3
U (cm.sec-1) 0.9827 U – 25173 C = 144306
W (cm-1.dyn-1) 0.9996 W – 1078.2 C = 2300.5
b (cm3.mol-1) 0.9989 b - 31.046 C = 73.261
Rm (cm-8/3.sec-1/3) 0.9997 Rm – 1890.7 C = 4087.5
η (poise) 0.9918 η - 1.30E-2 C = 6.80E-3
r 0.9830 r + 0.2863 C = 0.1866
KPV-4
U (cm.sec-1) 0.8698 U + 21885 C = 147324
W (cm-1.dyn-1) 0.9973 Rm -1963.5 C = 4105.6
b (cm3.mol-1) 0.8698 U + 21885 C = 147324
Rm (cm-8/3.sec-1/3) 0.9982 W – 1141.8 C = 2309.2
η (poise) 0.9943 η - 5.50E-3 C = 7.10E-3
r 0.8687 r - 0.2503 C = 0.1522
202
Parameters γ Correlation equation
KPV-5
U (cm. sec-1) 0.9942 U – 22115 C = 143244
W (cm-1.dyn-1) 0.9987 W – 1248.4 C = 2297.4
b (cm3.mol-1) 0.9982 b - 36.979 C = 73.299
Rm (cm-8/3. sec-1/3) 0.9982 Rm -2185.4 C = 4081
η (poise) 0.9665 η - 8.60E-3 C = 6.70E-3
r 0.9959 r + 8.87E-2 C = 4.385E-1
KPV-6
U (cm.sec-1) 0.9868 U - 11353 C = 144747
W (cm-1.dyn-1) 0.9995 W – 642.48 C = 2297.2
b (cm3.mol-1) 0.9996 b – 18.981 C = 73.077
Rm (cm-8/3.sec-1/3) 0.9993 Rm -1121.6 C = 4080.9
η (poise) 0.9979 η - 9.8E-3 C = 7.10E-3
r 0.9867 r + 0.1289 C = 0.1816
KPV-7
U (cm. sec-1) 0.9865 U + 14981 C = 147287
W (cm-1.dyn-1) 0.9988 W – 856.81 C = 2317.3
b (cm3. mol-1) 0.9985 b - 28.42 C = 73.455
Rm (cm-8/3.sec-1/3) 0.9982 Rm – 1416.3 C = 4122.4
η (poise) 0.9692 η - 2.09E-2 C = 7.20E-3
r 0.9866 r – 0.1714 C = 0.1526
KPV-8
U (cm.sec-1) 0.9767 U + 24142C = 147934
W (cm-1.dyn-1) 0.9996 W – 1133.3 C = 2305.5
b (cm3.mol-1) 0.9998 b - 39.457 C = 72.938
Rm (cm-8/3.sec-1/3) 0.9994 Rm -1953.5 C = 4098.1
η (poise) 0.9977 η - 4.22E-2 C = 9.50E-3
r 0.9767 r - 0.2766 C = 0.1452
203
Fig. 4.5.3 : Variation of Inter molecular free path length (Lf) against
concentration for Schiff bases in DMF at 308.15 K.
0.42
0.43
0.44
0 0.04 0.08 0.12
Concentration (M)
L f (
A0 )
KPV - 5KPV - 6KPV - 7KPV - 8
204
Fig. 4.5.4 : Variation of Inter molecular free path length (Lf) against
concentration for Schiff bases in DMSO at 308.15 K.
0.38
0.39
0.40
0 0.04 0.08 0.12
Concentration (M)
L f (
A0 )
KPV - 1KPV - 2KPV - 3KPV - 4
0.38
0.39
0.40
0.41
0 0.04 0.08 0.12
Concentration (M)
L f (
A0 )
KPV - 5KPV - 6KPV - 7KPV - 8
205
Table 4.5.5 : The correlation coefficient (γ) and correlation equations
between some acoustical parameters and concentrations (C)
of Schiff bases in DMSO solutions at 308.15 K.
Parameters γ Correlation equation KPV-1
U (cm.sec-1) 0.9636 U + 13189 C = 149405
W (cm-1.dyn-1) 0.9994 W - 650.53 C = 2187.00
b (cm3.mol-1) 0.9996 b - 22.016 C = 67.738
Rm (cm-8/3.sec-1/3) 0.9992 Rm – 1107.6 C = 3810.9
η (poise) 0.9209 η - 1.19E-2 C = 1.62E-2
r 0.9636 r - 0.1532 C = 0.1281
KPV-2
U (cm.sec-1) 0.9714 U + 10630 C = 146816
W (cm-1.dyn-1) 0.9999 W – 815.41 C = 2175.4
b (cm3.mol-1) 0.9999 b - 27.032 C = 67.653
Rm (cm-8/3.sec-1/3) 0.9998 Rm – 1392.9 C = 3787.2
η (poise) 0.9950 η - 2.55E-2 C = 1.37E-2
r 0.9711 r - 0.1215 C = 0.158
KPV-3
U (cm. sec-1) 0.9825 U + 12351 C = 148031
W (cm-1.dyn-1) 0.9989 W – 675.06 C = 2178.9
b (cm3.mol-1) 0.9983 b - 22.312 C = 67.621
Rm (cm-8/3.sec-1/3) 0.9984 Rm – 1121.9 C = 3794.3
η (poise) 0.9275 η - 2.24E-2 C = 1.62E-2
r 0.9823 r – 0.1422 C = 0.144
KPV-4
U (cm .sec-1) 0.9857 U + 21436 C = 149268
W (cm-1.dyn-1) 0.9990 W – 816.77 C = 2180.1
b (cm3.mol-1) 0.9996 b - 27.968 C = 67.502
Rm (cm-8/3.sec-1/3) 0.9986 Rm – 1366.7 C = 3796.7
η (poise) 0.9808 η - 2.06E-2 C = 1.71E-2
r 0.9858 r – 0.2479 C = 0.1297
206
Parameters γ Correlation equation
KPV-5
U (cm.sec-1) 0.9776 U -48395 C = 143900
W (cm-1.dyn-1) 0.9996 W – 1164.8 C = 2155.3
b (cm3.mol-1) 0.9999 b - 31.321 C = 67.316
Rm (cm-8/3.sec-1/3) 0.9995 Rm – 2072.4 C = 3746.5
η (poise) 0.9828 η - 3.54E-2 C = 1.71E-2
r 0.9786 r + 0.5531 C = 0.1913
KPV-6
U (cm.sec-1) 0.9946 U + 43540 C = 147136
W (cm-1.dyn-1) 0.9964 W – 264.99 C = 2167.7
b (cm3.mol-1) 0.9994 b - 13.88 C = 67.333
Rm (cm-8/3.sec-1/3) 0.9932 Rm – 388.76 C = 3771.7
η (poise) 0.9682 η + 2.31E-2 C = 2.12E-2
r 0.9944 r – 0.4927 C = 0.1545
KPV-7
U (cm.sec-1) 0.9772 U + 56526 C = 151067
W (cm-1.dyn-1) 0.9962 W – 643.516 C = 2187.4
b (cm3.mol-1) 0.9999 b - 26.838 C = 67.53
Rm (cm-8/3.sec-1/3) 0.9941 Rm – 1044.2 C = 3811.6
η (poise) 0.9807 η - 5.60E-2 C = 1.63E-2
r 0.9781 r – 0.6524 C = 0.1088
KPV-8
U (cm.sec-1) 0.9989 U + 45359 C = 1511937
W (cm-1.dyn-1) 0.9991 W – 755.45 C = 2189.2
b (cm3.mol-1) 0.9994 b - 28.763 C = 67.485
Rm (cm-8/3.sec-1/3) 0.9987 Rm – 1238.6 C = 3815.2
η (poise) 0.8773 η - 7.92E-2 C = 1.69E-2
r 0.9988 r – 0.5298 C = 0.0984
207
Fig. 4.5.5 : Variation of isentropic compressibility (κs) against
concentration for Schiff bases in DMF at 308.15 K.
4.8
5.0
5.2
0 0.04 0.08 0.12
Concentration (M)
ise.
com
p.10
11 (c
m2 /d
yn)
KPV - 5KPV - 6KPV - 7KPV - 8
208
Fig. 4.5.6 : Variation of isentropic compressibility (κs) against
concentration for Schiff bases in DMSO at 308.15 K.
3.9
4.2
4.5
0 0.04 0.08 0.12
Concentration (M)
ise.
com
p.10
11 (c
m2 /d
yn)
KPV - 5KPV - 6KPV - 7KPV - 8
4.1
4.2
4.3
4.4
0 0.04 0.08 0.12
Concentration (M)
ise.
com
p.10
11 (c
m2 /d
yn)
KPV - 1KPV - 2KPV - 3KPV - 4
209
Fig. 4.5.7 : Variation of Solvation number (Sn) against concentration
for Schiff bases in DMF at 308.15 K.
0
10
20
0.01 0.02 0.04 0.06 0.08 0.1
Concentration (M)
S n
KPV - 1KPV - 2KPV - 3KPV - 4
0
5
10
0.01 0.02 0.04 0.06 0.08 0.1
Concentration (M)
Sn
KPV - 5KPV - 6KPV - 7KPV - 8
210
Fig. 4.5.8 : Variation of Solvation number (Sn) against concentration
for Schiff bases in DMSO at 308.15 K.
0
40
80
0.01 0.02 0.04 0.06 0.08 0.1
Concentration (M)
S nKPV -1KPV - 2KPV - 3KPV - 4
-10
0
10
0.01 0.02 0.04 0.06 0.08 0.1
Concentration (M)
Sn
KPV - 5KPV - 6KPV - 7KPV - 8
211
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216
Introduction:
Thermal analysis includes a group of techniques in which specific
physical properties of a material are measured as a function of temperature or
time. The production of new high-technology materials and the resulting
requirement for a more precise characterization of these substances have
increased the demand for thermal analysis techniques. Thermal analysis has
been used to determine the physical and chemical properties of polymers,
electronic circuit boards, geological materials and coal. These analysis are
also important for environmental measurements, composition analysis,
product reliability, stability, chemical reactions and dynamic properties.
Among the thermal methods, the most widely used techniques are
thermogravimetry (TG), differential thermal analysis (DTA) and differential
scanning calorimetry (DSC) which find extensive use in chemistry,
biochemistry, metallurgy, materials science and various other areas. Further,
these techniques throw light on molecular architecture, degree of
polymerization, the extent of chain branching, on the kinetics of degradation,
etc[1-4]. Le Chaterlier[5,6] was the first to use thermal transformations of
materials as an analytical tool. Later on, a number of workers used these
techniques in a number of fields[7-12]. Thermal analysis is useful in both
quantitative and qualitative analysis.
In Thermo Gravimetric Analysis (TGA), the mass of a sample is
monitered as a function of temperature or time, when it is subjected to a
programmed temperature change in a specified atmosphere. The plot of a
mass change versus temperature is termed as a thermo gravgram or TG
curve.
Differential Thermal Analysis (DTA) is the oldest thermal technique in
which the difference of temperature between the sample and a reference
material is measured as a function of temperature while the substance and
reference material are subject to a controlled temperature program. This is
widely used in determining the thermal behavior and composition of naturally
occurring and manufactured products. It is of great importance in the field of
ceramics, mineralogy and metallurgy.
217
In differential scanning calorimetry (DSC), the energy necessary to
establish zero temperature difference between a substance and reference
material is recorded as a function of temperature or time. DSC provides useful
information about physical transformation such as melting, freezing,
volatilization, glass transformation, crystal-crystal transition, crystallization from
melt, crystalline disorientation etc. It is widely used to provide quantitative and
qualitative information about physical and chemical changes involving
endothermic or exothermic processes or heat capacity changes [13,14].
Literature survey shows that various workers studied thermal
properties of a large variety of compounds such as drugs, ceramics,
composites, geological materials, biological materials, polymers and other
organic and inorganic compounds[15-20]. Mital et al[21] reported kinetics of some
complexes. Ghani and Sherif also reported thermogravimetric studies of some
lanthanum complexes[22]. Low and Ishida[23] reported the effect of aliphatic
amines on thermal decomposition of polybenzoxazines. Thermo gravimetric
studies of some Schiff base complexes have also been reported[24].
Bhatt et al[25] studied thermal properties of some new bis (2,4-
pentanedionato)-zirconium aryl oxides. Matsumoto et al also studied thermal
behavior of some complexes[26].
In the present work, thermal analysis of some Schiff bases derived
from p-amino phenol have been done by TG, DTA and DSC techniques.
From TG curves, various kinetic parameters can be evaluated by
several methods. It is assumed that thermal and diffusion barriers are
negligible because small quantity of material is used, the shape of any TG
curve depends on the nature of apparatus and the way in which it is used.
Further, in all these method, Arrhenius equation is valid.
The kinetic treatments are based on the following:
dC/dt = K f (C) ……(4.6.1)
where C is the degree of conversion, t is time and K is rate constant. f(C) is a
temperature independent function of C.
218
The constant K is assumed to have the Arrhenius form:
K = A e -E/RT ……(4.6.2)
C is defined as the conversion with respect to initial material and is given as:
C = 1-(W/W0) ……(4.6.3)
where W0 and W are the initial weight at t=0 and weight at any time t of the
material.
Equation (4.6.3) can be rearranged as:
(W/W0) = (1-C) …...(4.6.4)
W/W0 is known as residual weight fraction.
Thus, the rate of conversion is,
dC/dt = - (1/W0) (dW/dt) .......( 4.6.5)
For homogeneous kinetics, the conversion is assumed to be of the form:
f (C) = (1-C)n ......( 4.6.6)
where n is order of the reaction.
Substituting the values from equation (4.6.2) and (4.6.6) in equation
(4.6.1) gives:
dC/ dt = A e -E/RT (1-C)n
or dC/dt = (A/β) e -E/RT (1-C)n ......( 4.6.7)
where A is the frequency factor, β is the rate of heating and E is the energy of
activation.
Various methods for single and multiple heating rates have been
reported [20-24]. The methods of single heating rate are as follows:
219
1. Freeman-Carroll[27] and Anderson-Freeman method[28] :
To analyze TG data at a single heating rate, Freeman and Carroll gave
the following equation:
ln(dC/dt)/ln (1-C) = n - E/R [(1/T)/(∆ln(1-C)] ......( 4.6.8)
A plot of left hand side against ∆(1/T)/[∆ln(1-C)] gives a straight line
with a slope equal to -E/R and the intercept is equal to n.
Anderson and Freeman used the following equation (4.6.8):
[∆ln(dC/dt)] = n [∆ln(1-C)] - E/R ∆(1/T) ......( 4.6.9)
The plot of [∆ln(dC/dt)] against [∆ln(1-C)] for equal intervals of ∆(1/T)
gives a straight line with slope equal to n and intercept -E/R ∆(1/T).
2. Sharp-Wentworth method[29] :
Sharp and Wentworth derived the following relation for first order
kinetics (n=1) to analyse the TG data:
log[(dC/dt)/(1-C)] = log (A/ β) – (E /2.303R).(1/T) .......( 4.6.10)
The plot of log [(dC/dt)/(1-C)] against 1/T would be a straight line with
slope equal to - (E/2.303R) and intercept equal to log (A/β).
3. Chatterjee Method[30] :
Chatterjee used the equation (4.6.11):
n = [log(dW/dt)1 - log(dW/dt)2]/(log W1-log W2) ...... (4.6.11)
where W1 and W2 are the sample weights.
4. Horowitz and Metzger method[31] :
The energy of activation E can be determined from a single TG curve by
the relation:
ln [ln(1-C)-1] = (E/RTs2)θ ...... (4.6.12)
220
where θ = T-Ts. T s is the temperature at which the rate of decomposition is
maximum.
Using the following equations (4.6.13) and (4.614) the frequency factor A
and entropy change ∆S can be determined.
ln E - ln (RTs2) = ln A - lnβ - E/RTs ...... (4.6.13)
A = (kbT / h) e ∆S/R ...... (4.6.14)
where kb is Boltzmann constant and h is Planck's constant.
221
Experimental :
The differential scanning calorimetric (DSC), Thermogravimetric
analysis (TG) and Differential thermal analysis (DTA) measurements were
made on the instrument “Universal V2.6D TA Instrument” at the heating rate
of 100 C per minute in nitrogen atmosphere for Schiff bases.
222
Results and Discussion :
The TG/DTA and DSC thermograms of some Schiff bases are given in
Figures 4.6.1 to 4.6.16 Various thermal properties such as initial
decomposition temperature (IDT), the decomposition temperature range and
the maximum degradation along with the percentage weight loss and
Exo/Endo transitions of Schiff bases are reported in Table 4.6.1.
It is observed from the Table 4.6.1 that initial decomposition
temperature is minimum for KPV-6 and maximum for the KPV-2. So, the
stability of Schiff bases in terms of initial decomposition temperature
decreases in the order: KPV-6 > KPV-4 > KPV-7 > KPV-3 > KPV-1 > KPV-8 >
KPV-5 > KPV-8. The stability depends upon the type of groups present in the
compound, their structure and bonding. The decomposition of each Schiff
base takes place in at least two steps. In first step, % weight loss is maximum
for KPV-2 and minimum for KPV-4 whereas in the second step, % weight loss
is maximum for KPV-1 and minimum for KPV-7.
The kinetic parameters, such as order of the degradation (n), energy of
activation (E), frequency factor (A) and entropy change (∆S) are reported in
Table 4.6.2 along with correlation coefficient (γ). The Freeman- Anderson
plots for KPV-7 for both steps are given in Figure 4.6.17.
Table 4.6.2 shows that for the first step, order of reaction is maximum
for KPV-6 and minimum for KPV-2. For all the Schiff bases, the values are
more than one. Similarly, for the second step also, order of reaction is higher
than one and is maximum for KPV-1. The energy of activation is found to be
greater in second step. For first step, energy of activation is maximum for
KPV-2 and minimum for KPV-3. However, for the second step, it is maximum
for KPV-6 and minimum for KPV-1. The frequency factor A is also observed to
be maximum for KPV-2 and minimum for KPV-6 and KPV-3 for the first step.
However, in the second step, A is maximum for KPV-6 and minimum for KPV-
1. Overall, wide range of A is observed in both the steps. The change in
entropy for all the Schiff bases is negative, which indicates that the transition
state is in more ordered state. The entropy of Schiff bases is maximum for
KPV-2 in the first step and KPV-6 in the second step.
223
Thus, it is concluded that thermal properties suggest that thermal
stability depends upon the type of substituent present. Considering
decomposition temperature, It is observed that presence of o-chloro
benzyldehyde (as in KPV-2) increases the stability whereas furfural group (as
in KPV-6) decreases the stability.
240
Table 4.6.1 : GA, DTA and DSC data for the Schiff bases.
Compd. Code.
Amt. (mg)
IDT
(0C)
Decomp. range.
(0C)
%Wt left
ResidualWt.
(mg)
Temp. of max. Degra.
(0C)
Transition DSC
(0C)
DTA
(0C)
Exptl. M. P (0C)
KPV - 1 2.1126 203.51 203.51 –261.76 59.34 4.53*
1.2537 0.0956*
232.62 Endo. Exo.
143.59 555.84
143.33 140
KPV – 2
2.1775 238.59 238.59 –290.60 31.33 5.58*
0.6422 0.1215*
264.35 Endo. Exo
Exo Endo
152.54255.36
141.99 235.73 578.48 652.44
122
KPV - 3 1.6836 198.23 198.23 –267.20 66.25 4.58*
1.1153 0.0788*
232.59 Endo. Endo Exo.
Endo Endo
193.51 60.37 183.53 501.71 634.84 698.14
165
KPV - 4 1.1266 184.60 184.60 –251.57 82.69 9.61*
0.9315 0.1082*
219.93 Endo. Exo. Exo
161.17227.43
152.51 246.64 599.96
166
KPV - 5 1.9106
224.18 224.18 –279.51 75.11 6.99*
1.4350 0.1335*
253.82 Endo. Endo Exo. Exo
166.19
264.04
160.34 220.37 577.96 726.28
162
KPV - 6 1.9836 171.07 171.07 –214.48 74.28 6.55*
1.4734 0.1299*
191.63 Endo.
Exo
121.70 175.74 709.94 220.46
214
KPV - 7 0.5947 187.41 187.41 –256.02 57.95 19.57*
0.3446 0.1164*
222.12 Endo. Endo Exo. Exo Exo
186.17
267.23
407.85 589.17 635.77 686.54
210
KPV - 8 1.2454 220.43 220.43 –280.89 69.86 8.97*
0.8700 0.1118*
256.17 Endo.
Exo.
208.54
275.33
201.44 479.61 658.10
182
* For the second step
241
Table 4.6.2 : The kinetic parameters for the 1st step.
Comp. code. n E, KJ A sec-1 ∆S°, JK-1 γ
KPV - 1 2.61 50.4163 8.33 x 103 -174.719 0.97
KPV - 2 1.88 110.3565 8.30 x 109 -60.0268 0.99
KPV - 3 4.08 13.7859 7.22 x 10-1 -252.199 0.99
KPV - 4 2.72 18.5467 2.73 -241.226 0.98
KPV - 5 3.68 15.7359 9.58 x 10-1 -250.305 0.97
KPV - 6 4.85 19.0692 7.21 x 10-1 -254.406 0.99
KPV - 7 2.01 21.7492 6.69 -233.78 0.99
KPV - 8 2.41 34.9378 1.29 x 102 -209.642 1.00
Table 4.6.3 : The kinetic parameters for the 2nd step.
Comp. code. n E, KJ A sec-1 ∆S°, JK-1 γ
KPV - 1 2.40 67.17009 1.26 x 103 -193.843 0.99
KPV - 2 1.64 155.4844 4.49 x 108 -87.9753 0.97
KPV - 3 1.67 158.8658 4.16 x 109 -68.9035 1.00
KPV - 4 1.73 101.9758 1.07 x 105 -157.513 1.00
KPV - 5 2.08 107.4423 3.22 x 104 -168.525 0.99
KPV - 6 1.71 232.0059 6.18 x 1011 -28.905 0.99
KPV - 7 1.45 142.1043 8.47 x 107 -101.727 0.99
KPV - 8 1.93 86.56231 2.76 x 103 -188.74 0.97
242
Fig. 4.6.17 : The Freeman-Anderson plots for KPV - 7 for [A] first step
and [B] for second step.
A
2.4
2.5
2.6
2.7
-0.0006 -0.00055 -0.0005 -0.00045 -0.0004 -0.00035
d(1/T)/dln(1-C)
ln(d
c/dt
)/ln(
1-C
)
B
1
2
3
-0.0001 -0.00008 -0.00006 -0.00004 -0.00002 0
d(1/T)/dln(1-C)
ln(d
c/dt
)/ln(
1-C
)
243
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245
Introduction :
Literature survey shows that Schiff bases are studied extensively
because of their various applications, especially in medical and biological
fields. Many Schiff bases have been known to be medicinally important and
are used to design medicinal compounds[1-3]. Many of them have been found
to demonstrate a wide range of pharmacological[4] activities, which include
antibacterial[5-11], antifungal[12,13], anti-HIV[14], antitumor[15-19], anti-
inflammatory[20], antipyretic[21-24] anticancer[25-28] etc. The antimicrobial
activities of Schiff bases derived from various aldehydes, amines, thiazoles,
benzothiazole, pyridoxal, amino acids, coumarins, triazoles and substituted
triazoles have been reported [29-35] .
In the present work, the antibacterial activities of some Schiff bases
derived from p-amino phenol are discussed.
246
Experimental :
The antibacterial activities of all the Schiff bases were studied in
dimethylformamide (DMF) and dimethylsulfoxide (DMSO).
Antibacterial testing :
The bacterial strains studied are identified strains and were obtained
from National Chemical Laboratory (NCL), Pune, India. Agar-ditch method
was used to study antibacterial activity of compound [33].
Three different concentrations i.e., 2 mg/0.1ml, 0.2 mg / 0.1 ml and 0.02
mg / 0.1 ml were prepared for all the Schiff bases in both DMF and DMSO.
A loop full of the given test strain was inoculated in 25 ml of N-broth and
was incubated for 24h in an incubator at 370C in order to activate bacterial
strain. Inoculation of the test strain was done by the Pour-plate technique.
0.2ml of the activated strain was inoculated into the media when it reached
40-450C temperature. It was then poured in the Petri plates and allowed to
solidify. After solidification of the media, ditch was made in the plates with the
help of cup-borer (0.85 cm) and then the solution of Schiff base in DMF and
DMSO was inoculated into the well. The activities of pure solvents were also
studied. The controls were maintained (for each bacterial strain and each
solvent), where 0.1ml of the pure solvent was inoculated into the well.
The inhibition zone formed by these compounds against the particular
test bacterial strain determined the antibacterial activities of all the
compounds.
The bacterial strains used are B. cereus-ATCC 11778, P. aeroginosa-
ATCC 27853, Escherichia coli-ATCC 25922, K. pneumoniae-NCIM 2719 and
Staphylococcus aureus-ATCC 25923.
247
Results and discussion :
The antibacterial activity of all the Schiff bases against the above
mentioned bacteria are shown in Figures 5.1 - 5.3. Fig. 5.1-A shows that all
the schiff bases could inhibit B. cer in both DMF and DMSO solvents.
However, inhibition is more in DMF than that in DMSO. This suggests that
solvent plays an important role in inhibition. In DMF, KPV-1 showed maximum
inhibition followed by KPV-4. Minimum inhibition is observed by KPV-6. In
DMSO also, KPV-1 showed maximum inhibition followed by KPV-6. Minimum
inhibition is observed by KPV-3, KPV-7 and KPV-8 in DMSO. In Fig. 5.1-B,
inhibition of all the bases is shown against E. coli in both the solvents. In
DMF, KPV-3 showed maximum inhibition followed by KPV-8. KPV-1 showed
minimum inhibition. But, in DMSO, only KPV-1 showed inhibition. Other bases
showed no inhibition at all. This again proves solvent effect on bacterial
activity.
All the Schiff bases have p-amino phenol as central moiety. The side
chains are different. Thus, in different solvents, different side chains show
different activity. KPV-1 has salicyldehyde as side chain, which is observed to
be most effective in both the solvents. KPV-6 has furfuraldehyde as side
chain, which is found to be least effective in DMF than in DMSO.
Fig. 5.2-A shows that against P. pneu also, KPV-1 is most effective in
both the solvents. However, inhibition is more in DMF than in DMSO. In DMF,
KPV-2, KPV-3 and KPV-6 showed minimum inhibition. KPV-4, KPV-5 and
KPV-8 are also quite effective in DMF. However, in DMSO, KPV-2, KPV-3
and KPV-8 showed no inhibition against P. pneu. Thus, salicyldehyde side
chain again proved to be more effective in DMF and DMSO against P. pneu.
Against K. pneu, all the bases had significant activity in DMF as shown
in Fig. 5.2-B. However maximum inhibition is observed by KPV-7, which
contains p-chloro benzaldehyde as side chain. In DMSO, KPV-5 showed
maximum activity whereas KPV-6 showed minimum activity. All other bases
had moderate activity against K. pneu. KPV-5 contains 3-nitro benzaldehyde
as side chain, which is found to more effective in inhibiting K. pneu. in DMSO
where as furfuraldehyde is least effective against this bacteria.
248
The inhibition against S. aur for all the bases in DMF and DMSO are
shown in Fig. 5.3. In DMF, inhibition is maximum than in DMSO. KPV-4 and
KPV-5 are most effective in both the solvents. In DMSO, KPV-6 and KPV-7
showed no inhibition. The results indicate that 2-nitro and 3-nitro
benzaldehyde side chains are most effective against S. aur. in both the
solvents where as furfuraldehyde and p-chloro benzaldehyde are not effective
at all against S. aur. in DMSO.
Thus, we conclude that inhibition depends upon three S; solvent,
structure and strain. Out of the two solvents studied, DMF proved to be better
solvent. p-amino phenol moiety is common in all bases but side chains are
different which has different effect on different bacterial strains in different
solvents. Overall, the base with salicyldehyde showed maximum inhibition
followed by nitro benzaldehyde side chain.
This implies that the p-amino phenol moiety with salicyldehyde and
nitro benzaldehyde side chains can be used as a lead molecule for drug
designing.
249
Fig. 5.1 : Antibacterial activity of Schiff bases against [A] B. cer [B] E. coli in DMF and DMSO solution.
[A]
0
1
2
3
4
5
6
7
8
9In
hibi
tion
zone
(cm
)
KPV-1 KPV-2 KPV-3 KPV-4 KPV-5 KPV-6 KPV-7 KPV-8
Compounds
DMFDMSO
[B]
0
1
2
3
4
5
Inhi
bitio
n zo
ne (c
m)
KPV-1 KPV-2 KPV-3 KPV-4 KPV-5 KPV-6 KPV-7 KPV-8
Compounds
DMFDMSO
250
Fig. 5.2 : Antibacterial activity of Schiff bases against [A] P. pneu [B] K. pneu in DMF and DMSO solution.
[A]
0
1
2
3
4
5
6
7In
hibi
tion
zone
(cm
)
KPV-1 KPV-2 KPV-3 KPV-4 KPV-5 KPV-6 KPV-7 KPV-8
Compounds
DMFDMSO
[B]
0
2
4
6
8
10
12
Inhi
bitio
n zo
ne (c
m)
KPV-1 KPV-2 KPV-3 KPV-4 KPV-5 KPV-6 KPV-7 KPV-8
Compounds
DMFDMSO
251
Fig. 5.3 : Antibacterial activity of Schiff bases against S. aur in DMF and DMSO solution.
0
1
2
3
4
5
6
7
8
Inhi
bitio
n zo
ne (c
m)
KPV-1 KPV-2 KPV-3 KPV-4 KPV-5 KPV-6 KPV-7 KPV-8
Compounds
DMF
DMSO
252
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255
A COMPREHENSIVE SUMMARY OF THE WORK
CHAPTER – I This chapter describes the literature survey on Schiff bases
and Thiazolidinones, their characterization and physico-
chemical properties.
CHAPTER – II The synthesis of Schiff bases and thiazolidinones are
described in this chapter along with their physical constant
data.
CHAPTER – III The characterizations of all the synthesized compounds are
done by IR, NMR and mass spectral data. The spectra and
the characteristic peak positions of IR and NMR spectra are
reported. Further, mass spectra and possible fragmentation
schemes are given in this chapter.
CHAPTER – IV The physicochemical properties of some Schiff bases were
also studied and are given in this chapter. The different
properties are given in different sections.
Section : 1 In this section, heat of solution of all the Schiff bases
derived form p-amino phenol were
determined at 308.15 K in DMF and
DMSO. It is observed that the solubility of Schiff bases is
greater in DMSO than in DMF. KPV-2 shows maximum
solubility in both the solvents. However, in DMSO, KPV-5
shows minimum solubility whereas in DMF, KPV-1 exhibited
minimum solubility. The heats of solution are observed to be
positive for all the Schiff bases in both the solvents
indicating thereby endothermic behavior of these bases in
these two solvents.
Section : 2 In this section, the densities of Schiff bases were measured
in DMF and DMSO at 308.15 K. The experimental density
256
values are in good agreement with those calculated
theoretically for some cases where as in others, deviations
between theoretical and experimental densities are larger
which may be due to salvation of ions in solution.
Section : 3 This section describes the conductance of some Schiff
bases in DMF and DMSO at 308.15 K. It is observed that all
Schiff bases are weak electrolytes in nature.
Section : 4 In this section, the dissociation constants of Schiff bases in
water - dioxane mixtures are studied at 308.15 K. The acidic
character depends on the type of substituent group. It is
observed that presence of –Cl or –NO2 group at ortho
position increases the acidic character whereas at para
position, the acidic character is found to decrease. So KPV-
2 and KPV-4, showed maximum acidic character.
Section : 5 This section describes the acoustical properties of Schiff
bases in DMF and DMSO at 308.15 K. These acoustical
properties are very useful for the understanding of
interactions occurring in the solutions. It is observed that in
both DMF and DMSO solutions, except KPV-6, other bases
shows structure forming tendency. KPV-6, exhibit structure
breaking tendency in both the solvents. The nature of
groups present in Schiff base played an important role in
the predominance of the interaction.
Section : 6 The thermal properties of Schiff bases are described in this
section. DSC, TGA and DTA thermo grams were scanned
at the heating rate of 100 C per minute. Thermal stability
depends on the presence of substituent in the compound. It
is observed that KPV-2 is most stable whereas KPV-6 is
257
least stable. Various kinetic parameters such as order of
reaction, energy of activation, frequency factor and entropy
were also calculated. The negative entropy for all the
studied Schiff bases indicates the more ordered transition
state.
CHAPTER – V The antibacterial activities of some Schiff bases are
explained in this chapter. For p-amino phenol Schiff bases,
study was done in DMF and DMSO. DMF is proved to be
better solvent. The Schiff base KPV-1 with salicyldehyde
showed maximum inhibition followed by ortho and para nitro
benzaldehyde side chains (KPV-4 and KPV-5).
258
LIST OF PAPERS COMMUNICATED :
(1) Evaluation of antibacterial activity of some Schiff bases.
Shipra Baluja, j. Parekh, S. Chanda and K. P. Vaishnani.
- Croatica Chem. Acta.
(2) Dissociation constants of some Schiff bases.
Shipra Baluja, Nikunj Kachhadia, P. K. Kasundra and K. P. Vaishnani
- Institution of Chemist.
(3) Physicochemical properties of Schiff bases.
Shipra Baluja, Asif Solanki, P. K. Kasundra and K. P. Vaishnani
- J. Indian Chem. Soc.
(4) Synthesis and antimicrobial studies of some thiazolidinones.
Shipra Baluja, j. Parekh, S. Chanda and K. P. Vaishnani.
- J. Serbian Chem. Soc.
(5) Ultrasonic studies of some derivatives of p-amino phenol.
Shipra Baluja, Nikunj Kachhadia, P. K. Kasundra and K. P. Vaishnani
- Fluid Phase Equilibria.
(6) Molecular interaction in solutions of some Schiff bases in DMF and
DMSO.
Shipra Baluja, Nikunj Kachhadia, P. K. Kasundra and K. P. Vaishnani
- Physics and Chemistry of Liquids.