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AlcoholsAlcohols, enols and , enols and phenolsphenols
Alcohols and alkyl halides are classified asAlcohols and alkyl halides are classified asprimaryprimarysecondarysecondarytertiarytertiary
according to their "degree of substitution."according to their "degree of substitution."
Degree of substitution is determined by countingDegree of substitution is determined by countingthe number of carbon atoms directly attached tothe number of carbon atoms directly attached tothe carbon that bears the halogen or hydroxyl group.the carbon that bears the halogen or hydroxyl group.
ClassificationClassification
CHCH33CHCH22CHCH22CHCH22CHCH22FF
CHCH33CHCHCHCH22CHCH22CHCH33
BrBr
primary alkyl halideprimary alkyl halide
secondary alkyl halidesecondary alkyl halide
ClassificationClassification
CHCH33CCHCCH22CHCH22CHCH33
OHOH
CHCH33
tertiary alcoholtertiary alcohol
HH
OHOH
secondary alcoholsecondary alcohol
IUPAC NomenclatureIUPAC Nomenclature
of Alcoholsof Alcohols
Name the alkyl group and add "alcohol" as aName the alkyl group and add "alcohol" as aseparate word.separate word.
Functional Class Nomenclature of AlcoholsFunctional Class Nomenclature of Alcohols
CHCH33CHCH22OHOH
CHCH33CHCHCHCH22CHCH22CHCH22CHCH33
OHOH
CHCH33CCHCCH22CHCH22CHCH33
OHOH
CHCH33
Name the alkyl group and add "alcohol" as aName the alkyl group and add "alcohol" as aseparate word.separate word.
Functional Class Nomenclature of AlcoholsFunctional Class Nomenclature of Alcohols
CHCH33CHCH22OHOH
CHCH33CHCHCHCH22CHCH22CHCH22CHCH33
OHOH
CHCH33CCHCCH22CHCH22CHCH33
OHOH
CHCH33
Ethyl alcoholEthyl alcohol
1-Methylpentyl alcohol1-Methylpentyl alcohol
1,1-Dimethylbutyl1,1-Dimethylbutylalcoholalcohol
Name as "alkanols." Replace -e ending of alkaneName as "alkanols." Replace -e ending of alkanename by -ol.name by -ol.
Number chain in direction that gives lowest numberNumber chain in direction that gives lowest numberto the carbon that bears the —OH group.to the carbon that bears the —OH group.
Substitutive Nomenclature of AlcoholsSubstitutive Nomenclature of Alcohols
CHCH33CHCH22OHOH
CHCH33CHCHCHCH22CHCH22CHCH22CHCH33
OHOH
CHCH33CCHCCH22CHCH22CHCH33
OHOH
CHCH33
Name as "alkanols." Replace -e ending of alkaneName as "alkanols." Replace -e ending of alkanename by -ol.name by -ol.
Number chain in direction that gives lowest numberNumber chain in direction that gives lowest numberto the carbon that bears the —OH group.to the carbon that bears the —OH group.
Substitutive Nomenclature of AlcoholsSubstitutive Nomenclature of Alcohols
CHCH33CHCH22OHOH
CHCH33CHCHCHCH22CHCH22CHCH22CHCH33
OHOH
CHCH33CCHCCH22CHCH22CHCH33
OHOH
CHCH33
EthanolEthanol
2-Hexanol2-Hexanol2-Methyl-2-pentanol2-Methyl-2-pentanol
OHOH
CHCH33
Substitutive Nomenclature of AlcoholsSubstitutive Nomenclature of Alcohols
Hydroxyl groups outrank Hydroxyl groups outrank alkyl groups when alkyl groups when it comes to numberingit comes to numberingthe chain.the chain.
Number the chain in theNumber the chain in thedirection that gives the direction that gives the lowest number to thelowest number to thecarbon that bears thecarbon that bears theOH groupOH group
CHCH33
OHOH
Substitutive Nomenclature of AlcoholsSubstitutive Nomenclature of Alcohols
6-Methyl-3-heptanol6-Methyl-3-heptanol
5-Methyl-2-heptanol5-Methyl-2-heptanol
OHOH
CHCH33
CHCH33
OHOH
alcohols and alkyl halides are polaralcohols and alkyl halides are polar
= 1.7 D= 1.7 D = 1.9 D= 1.9 D
Dipole MomentsDipole Moments
4646
+78+78
1.71.7
CHCH33CHCH22OHOH
MolecularMolecularweightweight
BoilingBoilingpoint, °Cpoint, °C
DipoleDipolemoment, Dmoment, D
Highest boiling point;Highest boiling point;strongest intermolecularstrongest intermolecularattractive forces.attractive forces.
Hydrogen bonding isHydrogen bonding isstronger than otherstronger than otherdipole-dipole attractions.dipole-dipole attractions.
Effect of Structure on Boiling PointEffect of Structure on Boiling Point
Hydrogen bonding in ethanolHydrogen bonding in ethanol
high yieldshigh yields
not reversible when carried outnot reversible when carried outin presence of pyridinein presence of pyridine
Reaction of Alcohols with Acyl ChloridesReaction of Alcohols with Acyl Chlorides
ROROHH HClHCl++ ++R'CClR'CCl
OO
R'CR'COROR
OO
a condensation reactiona condensation reaction
called Fischer esterificationcalled Fischer esterification
acid catalyzedacid catalyzed
reversiblereversible
EsterificationEsterification
ROROHH HH22OO++
HH++
++R'COHR'COH
OO
R'CR'COROR
OO
analogous to reaction with acyl chloridesanalogous to reaction with acyl chlorides
Reaction of Alcohols with Acid AnhydridesReaction of Alcohols with Acid Anhydrides
ROROHH ++ ++R'CR'COROR
OOOO
R'COCR'R'COCR'
OO
R'COHR'COH
OO
Esters of Inorganic AcidsEsters of Inorganic Acids
ROROH + HOH + HOEWGEWG ROROEWGEWG + H + H22OO
EWGEWG is an electron-withdrawing group is an electron-withdrawing group
HONOHONO22 (HO)(HO)22SOSO22 (HO)(HO)33PP OO++ ––
Primary alcoholsPrimary alcohols
Secondary alcoholsSecondary alcohols
from Hfrom H22OO
Oxidation of AlcoholsOxidation of Alcohols
RCHRCH22OHOH
OO
RCHRCH
OO
RCOHRCOH
OO
RCR'RCR'RCHR'RCHR'
OHOH
alcohol alcohol dehydrogenasedehydrogenase
Enzyme-catalyzedEnzyme-catalyzed
CHCH33CCHH22OHOH ++ NAD (a coenzyme)NAD (a coenzyme)++
++ ++ ++HHNADNAD HHCHCH33CCHH OO
Cleavage of Vicinal Diols by Periodic AcidCleavage of Vicinal Diols by Periodic Acid
CCCC
HOHO OHOH
HIOHIO44CC OO OO CC++
Enols and EnolatesEnols and Enolates
Enol-oxo tautomerismEnol-oxo tautomerism
CHCH33CHCH
OO
HH22CC CHCH
OHOH
KK = 3 x 10 = 3 x 10-7-7
CHCH33CCHCCH33
OO
HH22CC CCHCCH33
OHOH
KK = 6 x 10 = 6 x 10-9-9
Mechanism of EnolizationMechanism of Enolization (In general)(In general)
OO••••
CR'CR'
••••
RR22CC
HH
RR22CC CR'CR'
OO••••
•••• HH
percent enol is usually very smallpercent enol is usually very small
keto form usually 45-60 kJ/mol more stableketo form usually 45-60 kJ/mol more stablethan enolthan enol
Enol ContentEnol Content
RR22CHCR'CHCR'
OO
RR22CC CR'CR'
OHOH
enolenolketoketo
PhenolsPhenols
named on basis of phenol as parentnamed on basis of phenol as parent
substituents listed in alphabetical ordersubstituents listed in alphabetical order
lowest numerical sequence: first point oflowest numerical sequence: first point ofdifference ruledifference rule
5-5-ChloroChloro-2--2-methylmethylphenolphenol
NomenclatureNomenclature OHOH
CHCH33
ClCl
NomenclatureNomenclature OHOH
OHOH
1,2-Benzenediol1,2-Benzenediol
OHOH
OHOH
OHOH
OHOH
1,3-Benzenediol1,3-Benzenediol 1,4-Benzenediol1,4-Benzenediol
(common name:(common name:pyrocatechol)pyrocatechol)
(common name:(common name:resorcinol)resorcinol)
(common name:(common name:hydroquinone)hydroquinone)
name on basis of benzoic acid as parentname on basis of benzoic acid as parent
higher oxidation states of carbon outrankhigher oxidation states of carbon outrankhydroxylhydroxyl group group
NomenclatureNomenclature
pp-Hydroxybenzoic acid-Hydroxybenzoic acid
OHOH
COCO22HH
phenol is planarphenol is planar
C—O bond distance is 136 pm, which isC—O bond distance is 136 pm, which isslightly shorter than that of CHslightly shorter than that of CH33OH (142 pm)OH (142 pm)
Structure of PhenolStructure of Phenol
The OH group of phenols allows hydrogen bondingThe OH group of phenols allows hydrogen bonding
to other phenol molecules and to water.to other phenol molecules and to water.
Physical PropertiesPhysical Properties
HH OOOO
Hydrogen Bonding in PhenolsHydrogen Bonding in Phenols
Acidity of PhenolsAcidity of Phenols
most characteristic property of most characteristic property of
phenols is their acidityphenols is their acidity
CompareCompare OO HH••••••••
KKaa = 10 = 10-10-10
++HH ++
OO•••••••• ••••
––
CHCH33CHCH22OO HH••••
••••
KKaa = 10 = 10-16-16
++HH ++ CHCH33CHCH22OO••••
••••
––••••
Effect of strong electron-withdrawing groupsEffect of strong electron-withdrawing groupsis cumulativeis cumulative OHOH
NONO22
OHOH
NONO22
NONO22
OHOH
NONO22
NONO22
OO22NN
KKaa:: 7 x 107 x 10-8-8 1 x 101 x 10-4-4 4 x 104 x 10-1-1
CH(CHCH(CH33))22
OHOH
CHCH33
ThymolThymol
(major constituent of oil of thyme)(major constituent of oil of thyme)
Example: ThymolExample: Thymol
ClCl
OHOH
ClCl
2,5-Dichlorophenol2,5-Dichlorophenol
(from defensive secretion of(from defensive secretion of
a species of grasshopper)a species of grasshopper)
Example: 2,5-DichlorophenolExample: 2,5-Dichlorophenol
O-AcylationO-Acylation
(95%)(95%)
in the absence of AlClin the absence of AlCl33, acylation of the , acylation of the
hydroxyl group occurs (O-acylation)hydroxyl group occurs (O-acylation)
OOHH
CHCH33(CH(CH22))66CClCCl
OO
++
OOC(CHC(CH22))66CHCH33 OO
Typical Preparation is by Williamson SynthesisTypical Preparation is by Williamson Synthesis OONaNa ++ RRXX
OORR NaNaXX++
SSNN22
ExampleExample
acetoneacetone
heatheat
OONaNa ++ CHCH33II
OOCHCH33
(95%)(95%)
The most common examples of phenol oxidationsThe most common examples of phenol oxidationsare the oxidations of 1,2- and 1,4-benzenediolsare the oxidations of 1,2- and 1,4-benzenediolsto give quinones. to give quinones.
(76-81%)(76-81%)
QuinonesQuinones OHOH
OHOH
OO
OO
NaNa22CrCr22OO7,7, H H22SOSO44
HH22OO
The most common examples of phenol oxidationsThe most common examples of phenol oxidationsare the oxidations of 1,2- and 1,4-benzenediolsare the oxidations of 1,2- and 1,4-benzenediolsto give quinones. to give quinones.
(68%)(68%)
QuinonesQuinones
OO
OOAgAg22OO
diethyl etherdiethyl ether
OHOH
OHOH
CHCH33
CHCH33
AlizarinAlizarin(red pigment)(red pigment)
Some quinones are dyesSome quinones are dyes OO
OO
OHOH
OHOH
Ubiquinone (Coenzyme Q)Ubiquinone (Coenzyme Q)nn = 6-10 = 6-10
involved in biological electron transportinvolved in biological electron transport
Some quinones are important biomoleculesSome quinones are important biomolecules
CHCH33OO
CHCH33OO
OO
OO
CHCH33
nn
Vitamin KVitamin K(blood-clotting factor)(blood-clotting factor)
Some quinones are important biomoleculesSome quinones are important biomolecules OO
CHCH33
OO CHCH33 CHCH33 CHCH33 CHCH33
CHCH33