Part I

GENERAL PROCEDURE FOR THE SYSTEMATIC QUALITATIVE

ANALYSIS OF ORGANIC COMPOUNDS

i. Preliminary investigations.

a. Physical State.

b. Color

c. Odour.

d. Ignition on china porcelain.

e. Action of 30% sodium hydroxide solution.

f. Action of hot concentrated sulphuric acid.

g. Reaction with ferric chloride.etc.

ii. Detection of elements: Give details for the detection of nitrogen, sulphur and

halogens

iii. Detection of functional groups: Give the procedure for the detection of functional

groups especially for the group(s) that is found to be present.

iv. Determination of melting (boiling) point: The Compound is found to melt (boil)

at....C.

v. Probable Compound: On the basis of the standard data of the melting (boiling)

points of substances having particular functional groups(s), the given compound is

most probably.........

vi. Special tests of the compound: Give the special test(s), if any, for the particular

compound.

vii. Derivatives: Give the methods of the preparation of at least two important

derivatives and also mention their melting points observed by you.

1

Result:

Hence the given organic compound is:

1. Aromatic/Aliphatic

2. Saturated/Unsaturated

3. Special element present/Not present

4. Functional group present

5. Melting point

6. Probable compound based on melting point and derivatives prepared;

PRELIMINARY INVESTIGATIONS

1. Physical state and colour

In organic compounds the colour is generally associated with the presence of

certain functional groups i.e. particular group in the compound is responsible for a

particular shade. However, it should also be noted that several organic compounds are

colourless in the pure state but oxidized to coloured compound by atmospheric air,

e.g. amines. The different important groups along with their most usual colours are

summarized below in the solid and liquid states.

A. Solids

Colour Possible compounds

Yellow Iodoform, benzoin, Benzyl anthracene,

quionones and nitro compounds.

Orange Ortho-nitro aniline.

Pink Naphthols.

Brown

Diamines, aromatic higher amines and

aminophcnols.

2

B. Liquids

Colourless to red brown Amines.

Yellow to Orange Nitro compounds.

2. Odour.

Most of the organic compounds possess characteristic odowgtke- odour of

some compounds is so characteristic that it can be used even to distinguish the

particular class of compounds or sometimes even a single compounded from that of

others.

Odour Possible compounds

Carbolic or Phenolic Phenols

Naphthalene like Naphthalene, p-dichloro or p-dibromo benzene.

Mice like Acetamide.

Bitter almond like Benzaldehyde. nitrobenzene

Pleasant Alcohols, ethers, esters

Very pungent Lower aliphatic acids and their halogen derivatives.

3. Test for Aliphatic or aromatic nature:

i) Ignition

The nature of organic compound (whether aliphatic or aromatic) can be

established by the ignition test.

The compound is placed on a nickel spatula. The latter is then heated first

slowly and then strongly in a burner flame. If the compound burns with an non-smoky

flame, it is an aliphatic compound (except chloroform, chloral hydrate and ethyl

acetate which burn with a smoky flame); while if it burns with a sooty or smoky flame

the compound is aromatic in nature. The aliphatic and aromatic nature of compound

may further be ascertained by the following tests.

3

i. Nitration test. Take 1 gm. (or lml.) of the compound in a test-tube. Add

2ml. Of conc. HNO3 and 2ml. of conc H2SO4. Heat the contents for about

5 minutes,cool and pour the contents in cold water- formation of a yellow,

oily liquid or solid indicates the presence of an aromatic compound ;

otherwise it is an aliphatic compound.

ii. Le Rosen test. Take 0.2 gm. (or 3-4 drops) of the organic compound,3-4

drops of formaldehyde solution and 5ml, Of con H2SO4.Shake the

contents well and then warm-formation of red, orange, violet or green

colour or precipitate indicates the presence of an aromatic compound;

otherwise it is an aliphatic compound.

iii. Ignition on china porcelain: Place a small amount of the compound on a

porcelain dish and then heat it first gently and then strongly. Note the

change in appearance, the odour produced and the residue left.

Following are the notable observations and inferences of various important

compounds.

Observation Inference

Burns with luminous flame Aromajtic or unsaturated

Smoky flame... Aliphatic compounds

Smell of ammonia Amides

Violet vapours Iodoform

Chars but does not melt Uric acid, sulphonic acid, starch

Darkens, swells, chars with

Burnt Suger Odour

Carbohydrates, lartaratcs, lactates – 4 glucose

and some citrates.

4

4. Solubility

(i) Action of 20% sodium hydroxide solution:

Treat a small amount of the compound with nearly 5ml of the alkali solution

and note down the change in the cold state.

Observation Inference

Dissolves in NaOH, reprecipates on adding Aromatic acids, Phenol

Con. HCL

Mixture sets to a white solid Esters of diabasic acids

Highly coloured solution Nitrophenols, nitoracids, salicylaldehyde

Colour becomes deep on standing polyhydricphenols, some aminophenols

Yellow to brown resin Aliphatic aldehydes

Now heat the solution and note the change

Compound dissolves some esters or acid anhydrides

Ammonia is evolved Amides, imides, urea, thio-urea,

Yellow or brown solution sulphonamide sugars (except sucrose), polynitro

compounds, halogennophenols, halogenonitro

hydrocarbons.

Chloroform like odour Chloral.

ii) Action of hot concentrated sulphuric acid:

Treat a small amount of the given compound with concentrated sulphuric acid,

note the change and then warm it.

Observation Inference

Evolution of CO2 without charring urea.

Evolution of CO2 and CO.

And mixture becomes yellow

without charring.

Aliphatic hydroxy acids

Evolution of CO and /or CO2

And SO2 with immediate blackeningCarbohydrates, aliphatic hydroxy acids.

Blackening but no effervescences. Polyhydric phenols.

Pungent vapours without charring Carboxylic acids (simple)

5

iii) Action of NaHCO3:

0.l g of the substance treated with 2ml of saturated NaHCO3 soln.

Dissolves with brisk effervescence of CO2 Acid or acidchloride.

iv) Action of Dil. HCl:

0.5g of the substance treated with 2ml of dil. HCI and shake well.

Dissolves in HC1 and reappears on adding Basic substance (Amines)

10% NaOH solution.

5. Reaction with Neutral ferric chloride:

This regent is frequently used for identifying the presence of phenols and

aliphatic a-hydroxy acids., Take nearly two ml. of the compound solution either in

water or in alcohol and add to it one or two drops of neutral ferric chloride solution

and note the changes as below.

Observation Inference

Red colour but disappears Lower fatty acids, maleic acid

by adding dil.HCL. or amino acid.

Intense transitory bluish-green o-phenylene diamine

Colour.

Intense red-brown colour ortho or meta-phenylene diamine.

Or ppt.

Purple colour salicylaldehyde, salicylic acids, salicylamide

acetylsalicylic acid, phenyl salicylate.

Blue or red colour Phenols, resorcinols, cresols, arninophenols.

Greenish colour or ppt. Catechol. Quinolnes of naphthol.

Deep yellow colour aliphatic a-hydroxy acids

Pale brown ppt. dissolves in

div HCL

Dicarboxyiic acids soluble in water.

Ferric chloride may also be used for identifying certain amines. In practice, the

compound is dissolved in dilute hydrochloric acid and two drops of ferric chloride

solution are added to the solution.

6

Observation Inference

Green or blue green colour diphenylarnine, aniline

N-methylaniline

Violet colour P-anisidine.

Red colour P-phenetidine.

Red ppt. O-phanylenediamine.

Blue ppt. O-naphthylamine, o-toluidine.

6. Reaction with Tollen's reagent:

0.1 g of the substance dissolved in suitable solvent and add 2ml of Tollen's

reagent. Warm on water bath.

Black ppt or bright silver mirror Presence of Aldehydes, carbohydrates,

polyhydric Phenols or other reducing agents

7. Test for saturation or Unsaturation

1. Action of potassium permanganate: Potassium permanganate is a very

important oxidizing agent in neutral, acid as well as in alkaline medium.

i. In neutral medium:

Dissolve the substance in water and then add to it 4-5 Drops of neutral

potassium permanganate solution with constant shaking -violet colour discharged in

case of olefinic compounds.

ii. In acidic medium:

Perform above test using potassium permanganate solution acidified with

dilute sulphuric acid and then warm the contents-violet colour discharged in case of

olefinic compounds, or easily oxidisable compounds (aldehydes, ketones, oxalates

and formates.)

iii. In alkaline medium:

Perform the test as in (i) but using solution made alkaline with a few drops of

dilute sodium carbonate solution -violet colour discharged in case of aldehydes,

Phenolic acids, formates and cinnamates.

7

In case colour is discharged on warming –a hydroxy acids, viz, citric, lactic,

tartaric, etc. may be present.

2. 0.4 g of the substance +1 ml of water 3-4 drops of Bromine water. Shake well.

Yellow colour decolorized. Unsaturated compound

Yellow color persist Saturated compound

Yellow color decolorized & ppt

is Formed Saturated compound - amines, phenol.

8. TESTS FOR SPECIAL ELEMENTS

1. Lassaigne's test for nitrogen, sulphur and halogens:

Preparation of Lassaigne's extract of sodium fusion extract: Place a few

crystals or drops of an unknown compound in a fusion tube. Mold the test tube in an

inclined position and place a freshly cut out piece (the size of a wheat grain) of

sodium metal slightly above the substance. Mold the test tube horizontally using tongs

or wooden clamp. First heat sodium until it melts. Now set the test tube in the vertical

position so that the hot drops fall onto the test-substance. Meat the mixture to redness.

Plunge the red hot tube once in a china dish having nearly 10-15 ml. of distilled water

when the fusion tube will be torn out, if not, do so yourself with the help of tongs.

Boil the resulting product. Filter the hot solution and wash the residue with small

amount of distilled water. The filtrate so obtained is known as Lassaige's filtrate or

extract and used for testing nitrogen, sulphur and halogens. Lassaigne's extract should

be colourless. Yellow or brown colour indicates incomplete decomposition of the

original substance. If so, repeat the experiment using a new portion of the same

substance.

Na + C+N NaCN

2 Na + S Na2S

Na + C + S+N NaSCN

Na + X NaX

8

i. Test for nitrogen: Take a small quantity of the extract in a test tube and make

it alkaline (if it is not so) by adding a few drops of sodium hydroxide. Add 0.1

to 0.2 gms, of solid ferrous sulphate (a black precipitate will appear if sulphuc

is present), boil the resulting solution and then acidity it with cone. H2SO4 or-

HCL. The formation of Prussian blue precipitate or green colour indicates the

presence of nitrogen.

6NaCN + FeSO4 Na4Fe (CN)6 +Na2SO4

Sodium ferrocyanide

o2

FeSO4 Fe2 (SO4)3

3Na4Fe (CN)6 + 3Fe2 (SO4)3 Fe4 (Fe(CN)6)3 + 6Na2SO4

ferric ferrocyanide

Precautions: (i) Since the yellow colour of ferric chloride fades the Prussian blue

colour, it is better to avoid the addition of ferric chloride during the above test.

Similarly, on the same ground acidification with conc. H2SO4 is preferred to

concentrated HCL.

(iii) Some compounds like urea and its derivatives although possess nitrogen, they do

not respond the above test; the reason being the deficiency of carbon in these

compounds and hence in the above test whenever there is some doubt, the whole of

the process must be repeated using mixture of the compound with some amount of

cane sugar to provide sufficient amount of carbon.

Function of conc. H2SO4 or HCL The function of the acid is to dissolve the

precipitate of ferrous or ferric hydroxide (formed by reaction with FeSO4 and NaOH)

as the ferrous or ferric sulphate or chloride.

FeSO4 + 2NaOH Na2SO4 + Fe(OH)2

Fe2(SO4)3 + 6NaOH 3Na2SO4 + 2Fe(OH)3

9

Fe(OH)2 FeSO4 or FeCI2 +2H2O

2Fe(OH)3 Fe2(SO4)3orFeCl3+6H20

Test for sulphur: Following tests may be adopted for sulphur.

i. Acidify the Lassaigne's extract with dilute acetic acid and then add a few

drops of lead acetate, a black precipitate will be formed.

(CH3COO) 2 Pb + Na2S 2CH3COONa + PbS

Black

ii. Add few drops of freshly prepared dilute solution of sodium nitroprusside

(since in aqueous solution, it is unstable) to the extract, the appearance of a

purple colour confirms the presence of sulpur.

Na2 [Fe(CN)5 NO] + Na2S Na4 [Fe(CN)5NO5]

Sod.nitroprusside Sod. Sodiom Sulphorino pruside

(Violet)

iii. Test for nitrogen and sulphur when present together:

During performing the test for nitrogen if a blood red colour is developed after

adding ferrous sulphate crystals, nitrogen and sulphur seem-to be present together.

6 NaSCN + Fe (SO4)3 2Fe (SCN)3 + 3Na2SO4

ferric sulphocyanide (red colour)

10

Conc.H2SO4

Or Conc. HCl

Conc. H2SO4

Or Conc HCl

9. DETECTION OF FUNCTIONAL GROUPS

The tests of various important functional group are summarized below.

1. CARBOXYLIC ACIDS

Most aliphatic carboxylic acids are soluble in cold water, while aromatic acids

are sparingly soluble in cold water but readily soluble in hot or boiling water. The

presence of carboxylic group can easily be the following tests.

(i) Litmus tests:

Like phenols, the carboxylic acids turn blue litmus solution to red. For this

test, one drop of blue litmus solution is added to the aqueous solution of the acid, the

appearance of red colour indicates the presence of a phenol or an acids.

Precaution: As sometimes (viz. in case of very weak acids) it becomes

difficult to note the change in colour thus the test must be performed on a white tile.

(ii) Sodium bicarbonate:

Add some drops of concentrated sodium bicarbonate solution to the acid in

test tube or better on a watch glass or a white tile. Evolution of effervescences of

carbon dioxide indicates the presence of a carboxylic group.

RCOOH + NaHCO3 RCOONa + H2O + CO2

Precaution: Some phenols like 2,4,6 -trinitrophenol and 2,4,6-tribromophenol

also behave like acids and hence evolve carbon dioxide on treatment with sodium

bicarbonate.

(iii) lodate-iodide test:

Grind equal amounts of the carboxylic acid, potassium iodide and potassium

iodatc, the appearance of brown colour owing to the formation of free iodine indicates

the presence of a carboxylic group.

6RCOOH+5KI+KIO3 6RCOOK+3H2O+3I2

In case the compound is liquid take a little amount of it, 5-6 drops of 2%

potassium iodide solution and 5-6 drops of 4% potassium iodate solution. Cork the

11

test-tube and place in boiling water for 1-2 minutes. Cool and add about 5-10 drops of

starch solution. Blue colour indicates COOH group.

(iv) Ester test:

Warm nearly 1 ml. of the acid, 2ml. of methyl or ethyl alcohol and a small

amount of concentrated sulphuric acid for 1-2 minutes on the water bath, in a test

tube. Cool and pour the solution to a china dish-having some sodium carbonate

solution, fruity smell of ester indicates the presence of acid

RCOOH + C2H5OH R.C-OC2H5+H2O

(v) Ferric chloride test:

Neutralize 0.5 gm of the acid with excess of ammonia in a boiling test tube.

Boil the solution to remove excess of ammonia, cool and a few drops of neutral ferric

chloride solution. Note the colour of the resulting solution and take out inference

according to the following facts.

A reddish brown colour or ppt. is obtained in case of aliphatic mono-

carboxylic acids.

A buff or brownish coloured precipitate is obtained in case of aromatic

acids and some aliphatic acids like succinic and adipic acids.

An intense yellow colour is obtained in case of alpha hydroxy acids this

test may also be applied as follows. First add a few drops of ferric chloride

to a dilute aqueous solution of phenol and then add this resulting violet

coloured solution to a solution of a alpha hydroxy acid in water the violet

colour is discharged and a deep yellow tinge appears.

A violet or bluish colour is obtained in case of o-substituted aromatic

hydroxy acids.

12

O

vi. Detection of unsaturation in acid:

i. Dissolve a small amount of the acid in chloroform or carbon tetrachloride and add

to 2-3 drops of bromine solution in the same solvent (i.e. either CHCL3 or CCL4).

Disappearance of bromine colour without evolution by hydrobormic acid suggests

the presence of unsaturation in the compound. On the other hand, if the bromine

colour is discharged with the evolution of hydrobromic acid, a phenol, aromatic

amino or enol is indicated. The evolution of hydrobromic acid may be easily

detected by exposing the vapours to a solution of silver nitrate in nitric acid held

on the end of a glass rod.

R.CH = CH.R + Br R.CHBr.CHBr.R

(ii) Baeyer's test:

Add one or two drops of 1-2 % KMnO4 solution to small amount of the acid

dissolved in water or acetone disappearance of purple colour indicates the presence of

unsaturation.

Precaution: Some easily oxidisable compounds like aldehydes, alcohols,

formic acid some aliphatic hydroxy acids phenolic acids also respond this test.

(vii) Test for Dicarboxylic acids: Mix 0.1 g of the substance with 0.5g of resorcinol

and 4drops of con. H2SO4 in a hard glass test tube. Heat for 3-5 minutes pour it into

dil. NaOH. An intense greenish yellow fluorescence indicates a Dicarboxylic acid.

13

OH OH

BrBr

+ HBr

R.CH-CH.R

R.CH = CH.R OH OH(O) + H2O

KmnO4R.CHO RCOOH(O)

KMnO4

KmnO4

2. ACID ANHYDRIDES

i. Dissolve the compound in benzene or chloroform and add some aniline to

the resulting solution. Warm the solution for nearly 1-2 minutes, and cool.

A white precipitate of anilide is formed.

iii Anhydrides produce fruity smelling esters when warmed with n-butyl

alcohol.

3. PHENOLS

i. Litmus test: Like acids. phenols also turn blue litmus solution colour to

red

ii. Sodium bicarbonate: Except highly negatively substituted phenols

(eg.picric acid), Phenols in general do not decompose sodium bicarbonate

solution (difference from acids)

iii. Ferric chloride test: Add one or two drops of neutral ferric chloride to a

dilute aqueous or alcoholic solution of the compound in a test tube, the

appearance of a characteristic colour (violet, blue or green) indicates the

presence of phenolic group.

6C6H5OH +FeCl3 [(C6H50)6Fe]-3 +3HCL +3H+

iv. Take a small amount of the phenol in a test-tube, add to it alkali and a

small quantity of a cold solution of diazotised1 p-nitroantiine solution (p-

nitro aniline with dil HCl followed by cold-NaNO2 solution) red color.

14

Ac2O+C6H5NH2 AcNHC6H5

CONHC6H5

COOHAnilic acid

+C6H5NH2

COOH

COOH

v. Phthalein test.

Take a little (nearly 0.2gm.) of the phenol and an equal amount of phthalic

acnhydride in a dry test tube. Add nearly 2-3 drops of concentrated sulphuric acid and

fuse the mixture gently for about 15 minutes. Cool and pour the contents to dilute

sodium hydroxide solution. Characteristic colours of dyes are obtained as below.

Compound Colour of the dye formed Compound Colour of the dye Formed

Phenol Red Resorcinol Green

o-Croseol Red Hydroquinone Deep violet

m-Cresol Bluish-purple α-Naphthol Green

Catechol Blue β-Napthol Very faint green

vi. Nitrous acid test: Take a little of the compound in a test iube, add nearly

1ml of Conc. H2SO4 and then add a little sodium nitrite. Shake the contents

and warm gently, appearence of green/purple or blue colour indicates the

presence of phenolic OH group. Transfer the contents in little water when

the blue colour changes to red or blue-red. The colour will again change to

blue or green on addition of a little 20% Sodium hydroxide.

15

vii. Azo dye test: Dissolve 2-3 drops of aniline in one ml. of concentrated

hydrochloric acid and cool it in ice. To this solution add a few drops of

cold sodium nitrite solution and then add this solution to a cold solution of

phenol in an excess of NaOH solution. Coloured solution or precipitate

indicates the presence of a phenolic group.

Tests for polyhydric Phenols: (i) Take about 2 ml. of dilute ammonium hydroxide or

NaOH solution and add to it a crystal as large as rice -grain of the original compound.

Shake the content of the test tube -formation of yellow colour changing to red-brown

indicates polyhydric phenols.

(ii) Take about 3-4 ml. of Tollen's reagent in a test -tube and add to it 1ml of the

aqueous solution of the original compound -a grey or brown precipitate is formed

immediately in case of catechol, quinol, pyrogallol, gallic acid and tannic acid; within

30 seconds in case of orcinal and phloroglucinol; and within 2 minutes in resorcinol.

4. ALCOHOLS

Alcoholic group can be detected by the following tests.

i. Action of sodium: Take nearly 1ml. of the alcohol (in case of solid, dissolve it in

the dry benzene or ether) in a test-tube and add to it a small piece of freshly cut

sodium-evolution of brick effervescences of hydrogen suggests the presence of

alcoholic group.

2ROH+2Na 2RONa+H2

(i) Reaction with acetyl chloride.

Take about 1 ml. of acetyl chloride in a dry test tube and add to it about 0.5

ml. of the original compound -vigorous reaction occurs (i.e bubbles are freely

evolved) with in 2 minutes with the evolution of HCL fumes. Bring a glass rod dipped

in NH4OH -white fumes of ammonium chloride are produced. When the reaction

(bubbles) stops, add one ml. of water to dissolve the remaining HCL gas; separation

of an oily layer along with the ester like odour Confirms the presence of alcohol.

16

ROH + CH3COCl ROCOCH3 + HCI

HCI + NH4OH NH4C +H2O

Distinction between primary, secondary and tertiary alcohols:

i. Take 1ml of pure acetone, one drop or 10 mg. of the alcohol and then one drop of

the chromic acid regent. stir the mixture immediately-greenish blue coloured ppt.

is formed within two seconds in case of primary and secondary alcohols. If no

precipitate or colour change occurs at once tertiary alcohol is indicated.

ii. Take 1 ml. of the compound in a test tube and add 5 ml. of lucas reagent with

shaking. Note the following observations formation of insoluble chloride layer at

once tertiary alcohol. Appearance of cloudiness within 5 minutes secondary

alcohol. Solution remains clear with some darkening primary alcohol.

iii. Dissolve 0.2 gm. of the compound in about 10 ml. of 0.01% solution of bromine

in carbon tetrachloride. Add about 0.2 gm. of N-bromosuccinimide and place the

test tube in a water bath at 80°C.Note the colour obtained.

Permanent orange colour Primary alcohol.

Transient orange colour Secondary alcohol.

No colour Tertiary alcohol.

5. CARBONYL COMPOUNDS (Aldehydes and ketones)

i. Aldehydes and ketones, in general, are detected by reaction with 2, 4-

dinitrophenylhyrazine it form crystalline 2.4-dinitro-phenylhyrazine.

Add 2 drops or 1.1 gm. of the substance in dilute HCL to 3ml. of the 2,4-

dinitrophenylhyrazine solution (reagent) in dilute HCL and shake the mixture-yellow,

orange or red coloured crystalline precipitate may be formed at once, or on allowing

the mixture to stand for 15 minutes, or on gentle warming on a water-bath.

17

ii. Sodium bisulphite test: Most of the aldehydes and ketones react with a

concentrated aqueous solution of sodium bisulphite to form a crystalline solid.

C=O + NaHSO3

iii. Solutions of many aldehydes and ketones develop red colour when treated with

sodium nitroprusside and alkali. To a solution, of the substance add 1ml of 3%

sodium nitroprusside solution and 5 drops of 10% NaOH (Red or pink color).

iv. It is important to note that the above tests are not positive in all aldehydes and

ketones. In case of ketones only those ketones which have at least one methyl or

ethyl group attached to the carbonyl group respond these tests.

v. Add Nessier's solution to extremely dilute aqueous solution of aldehydes or

ketones voluminous precipitates. This test is given only by simpler aldehydes and

ketones.

vi. Fehling's test: Mix 2ml. of fehling solution A (copper sulphate solution) and

Fehling solution B (alkaline tartarate solution). To the mixed solution add 3 drops

(or 0.15gm.) of the suspected compound and warm the resulting solution. The

appearance of a red precipitate of cuprous oxide indicates the presence of an

aldehydic group.

R-CHO + 2Cu(OH)2 R-COOH+Cu2O +2H2O

Note that some ketones like benzoin also reduce Fehling solution.

vii. Schiff's test: Add two drops of the compound under test to 2ml. of the reagent

(pararosaniline hydrochloride solution, the colour of which is just decolourised by

passing SO2). Shake the contents, appearance of a violet or red colour within two

minutes indicates the presence of an aldehyde.

18

OHC

SO3Na

19

AR

NH

SO2H

SO2 NH NH2 +2ArCHO

ShakeC

SO3H

H2N

NHC

Ar

HSO3

H

C N C

Ar

SO3H

H

viii. Tollen's Test: Take nearly 3-4 ml. of the freshly prepared Tollen's reagent in a

clean and dry test - tube and add to this 2-3 drops (or 0.1 gm. in case of solid) of

the substance. Shake the solution and if no reaction occurs in the cold, warm (not

Boil) the tube gently in a beaker of water at 50: The formation of a black

precipitate of metallic silver or silver mirror indicates the presence of a reducing

substance like aldehydes.

Precautions: (i) The reagent must freshly prepared but it must be washed

away after use. As it forms explosive substance if stored.

CHO + Ag2O COOH + 2Ag

(iii) Some ketones like pyruvic acid reduce the Tollen's reagent.

ix. Benedict's test: Add 5ml of Benedict's solution to 0.4ml. of 2% solution of the

compound. Boil the solution for two minutes and then cool rapidly. Formation of

a red precipitate suggests the presence of a reducing sugar or an aliphatic

aldehyde.

RCHO + 2Cu++ (as citrate complex) + 4OH-

6. CARBOHYDRATES

The carbohydrates may be detected by the following tests.

i. Molisch's test: Dissolve nearly 0.005gm. of the carbohydrate in one ml. of

water, add two drops of the molisch’s reagent (10% α-napthol in alcohol)

and shake. Now add carefully 2ml. of concentrated sulphuric acid along

the side of the test-tube and allow it to stand for 2 minutes. The formation

of a reddish violet colour at the junction of two liquids indicates the

presence of carbohydrate. /'Shake' the contents of the test-tube in a stream

of cold water, a deep purple solution is obtained, which on dilution with

cold water yields a violet precipitate.

20

Tollen's SilverReagent mirror

RCOOH + Cu2O + 2H2O(red)

Polysaccharides Monosaccharides Sulphuric +hydroxyfurfural

Triarylmethane compounds (Violet)

(iv). Barfoed's test: The test is used in differentiating the monosaccharides from

disaccharides. Take one ml. of the freshly prepared Barfoed's reagent (0.33 gm. of

neutral copper acetate dissolved in 5 ml. of cold 1% acetic acid) and add one ml. of

the carbohydrate solution to it. Heat the solution in a boiling water-bath, formation of

a red precipitate in the blue solution, or on the sides of the tube just above the liquid,

within two minutes indicates the presence of a monosaccharide (glucose, fructose or

galactose).

7. ESTERS

i. Esters are usually identified by their hydrolysis reaction. Take 2-3ml of ester

solution in a test tube, add some sodium hydroxide solution and a drop of

phenolphthalein, the pink colour will be developed. Heat the reaction mixture

for some time, the disappearance of pink colour indicates the presence of an

ester group.

RCOQR' +alkali + Phenolphthalein RCOOH + R'OH

8. ALIPHATIC PRIMARY AMINES

Aliphatic primary amines in general can be detected by the following tests.

i. Carbylamine reaction: Warm a small amount (0.05 - 0.1 gm. or 2 drops) of

the amine with 2 drops of chloroform and one ml. of alcoholic potash in a

test tube, a nauseating (foul) odour of isocyanide (carbylamine) indicates

the presence of a primary aliphatic or aromatic amine.

RNH2 +CHCl3+ 3KOH RNC+3KCl+ 3H2O

Note: It is always advisable to decompose the isocyanide formed by adding

concentrated hydrochloric acid before throwing it in the sink.

21

heat

Pink color Pink color discharged

ii. Reaction with nitrous acid: Dissolve nearly 0.2 gm. of the amine in 5ml.

of cone hydrochloric acid, cool it in ice and then add nearly 2ml. of ice-

cold sodium nitrite solution, brisk effervescences of nitrogen will be

evolved in case the compound is primary amine. Sometimes, warming on

the water-bath is required in order to evolve the nitrogen.

RNH2+ HONO ROH+N2+ H2O

iii. Rimini's test: Take fiearly 3-drops of the amino solution in 5ml.of water,

add to it 1ml. of acetone and a drop of sodium nitropursside solution,

appearance of a violet colour within two minutes indicates the presence of

primary aliphatic amino group.

9. AROMATIC PRIMARY AMINES

i. Carbylaminc reaction: Same as in aliphatic primary amines.

ii. Reaction with nitrous acid: Dissolve nearly 0.1 gm. of the given amine in

3ml. of concentrated hydrochloric acid in a small beaker or a large hard

glass test tube. Cool it in ice to nearly 0°C and to this add 5ml. of ice cold

sodium nitrite aqueous solution with constant shaking till a slight excess of

nitrous acid predominates in the solution. When the reaction ceases, add

ice cold solution of β-naphthol in alkali; the formation of a bright red,

orange red or reddish blue precipitate or colour indicates the presence of

primary aromatic amino group. The solubility of the dye in NaOH

indicates the presence of a hydroxyl group in the amine.

10. ALIPHATIC AND AROMATIC SECONDARY AMINES

i. Reaction with nitrous acid: Dissolve nearly 1 gm. Of the compound in 3-

5 ml. of dilute hydrochloric acid and cool it is ice cold water. To the above

solution add 4-5ml. 10% sodium nitrite solution drop wise and with

constant shaking. Allow the solution to stand or 5 minutes when a yellow

or white oil precipitate is produced.

ii. Simon's test: Take a few drops of the compound and add to it dilute

solution of sodium nitroprusside followed by a few drops of dilute

acetaldehyde solution-deep blue or violet colours will be produced within

five minutes.

22

11. AMINO-ACIDS

Aliphatic: The presence of one of these acids may detected by the followings

tests,

i. Add few drops of 0.2% solution of ninhydrin reagent to the aqueous solution of

the substance a blue colour is produced.

ii. Add a few drops of ferric chloride solution to aqueous or alcoholic solution of

amino acids (red colour is developed),

iii. Sorensen test: Take near about 0.5gm. of the compound in a test tube and

dissolve it in water or alcohol. Add two drops of phenolphthalein and then very

dilute sodium hydroxide solution till a pink colour is obtained, In other test tube

take the similar things in the similar order only with the difference that here the

amino acid is replaced by 40% formalin solution. Add the solution from the

second test tube to the first; the disappearance of the pink colour is indication of

the amino acid.

23

O

C

C

O

C

OH

OH

H2N.CHR.COOH

O

C

C

O

C = N

O

C

C

O

CO2 + RCHO + H2O

Amino acid

Blue Color

Aromatic:

a. Aromatic amino acids are more acidic than the aliphatic amino acids cause

a vigorous evolution of carbon dioxide from sodium bicarbonate.

b. They usually give reddish colour with ferric chloride solution.

c. Like aromatic primary amines, these undergo diazotisation with nitrous

acid which couple with alkaline 2-naphthol solution to give coloured azo

dyes.

12. ALIPHA TIC NITRO COMPOUNDS

i. Dissolve a small amount of the compound in concentrated sodium hydroxide

solution and then add an excess of sodium nitrite solution. Now add some amount

of water followed by dropwise addition of dilute sulphuric acid. The appearance

of a red colour which disappears on adding excess of acid and reappears on adding

alkali indicates the presence of a primary aliphatic nitro group. Secondary nitro

group on similar treatment produces a permanent dark blue or blue green colour

soluble in chloroform. Tertiary nitro compounds do not respond this test.

ii. Reduction in neutral medium: Dissolve nearly 0.5gm. of the substance in an

equirnolar mixture of alcohol and water by warming. Add to it some amount of

zinc dust and solid NH4C1. Meat the mixture to boil and allow the reaction to

comlete. Filter the solution and add Tollen's reagent to the filtrate, a black

precipitate or mirror will be developed.

24

Zn-NH4Cl

RNO2 RNHOH + H2O

RNHOH + Ag2O RNO + 2Ag + H2O

13. AROMATIC NITRO COMPOUNDS

(i) Aromatic nitro compounds give the

(ii) test above

14. AMIDES AND EVIIDES

i. Reaction with nitrous acid: Like primary amines, amides and imides evolve

nitrogen on treatment with nitrous acid.

RCONH2 + HONO RCOOH + N2+ H2O

ii. Reaction with alkali: Dissolve 0.2 gm of the amide in excess of concentrated

sodium hydroxide solution. Heat the solution to boil, smell of ammonia gas

indicates the presence of amide group.

RCONH2+NaOH RCOONa + NH3

The evolution of ammonia gas can also be detected by the following tests.

a. Bring a red litmus paper over the mouth of the test tube, it changes to blue.

b. Bring a glass red dipped with concentrated hydrochloric acid to the mouth

of the test tube-dense white fumes of ammonium chloride.

iii. Only for aromatic amides: To a little of the compound, add some hydroxylamine

hydrochloride solution in ethyl alcohol. Boil the contents for about five minutes,

cool and then add about 4-5 drops of dilute (5%) ferric chloride solution-bluish

red colour

C6H5CONH2 + NH2OHHC1 C6H5CONHOH + NH4CI

iv. Only for aromatic amides: To the aqueous solution of the aromatic amide add

about 7-8 drops of 6% hydrogen peroxide and heat the contents to boiling. Cool,

add 1-2 drops of dilute (5%) ferric chloride solution bluish red colour in cold

25

within a short time or a brown colour on warming.

C6H5CONH2+H2O2 C6H6CONHOH + H2O

Tests for Urea: Urea, being the typical member of simple amides, gives certain

characteristic special tests.

i. Biuret test: Fuse a small amount of the urea in a test tube until it just melts and

ammonia is evolved. After some time when it resolidifies dissolve it in 1 ml. of

dilute sodium hydroxide solution and then add one to two drops of very dilute

copper sulphate solution, a pink colour will be developed changing to violet and

lastly deep blue. This test is also given by ox amide and malonamide.

2NA2-C-NH2 NH2CONHCONH2 + NH3

ii. Xanthydrol test: Dissolve a small amount of the compound in 50% acetic acid

and add to it 1 ml. of 5% xanthydrol solution in methanol, a precipitate will

immediately be formed. The test is given by urea as well as its derivatives.

iii. Take small amount of urea in aqueous solution and add to it sodium hypobromite

solution, brisk effervescences of nitrogen and carbon dioxide will be evolved.

iv. Urea nitrate test: 0.1g of the substance +1ml of water +1ml of con. HNO3. Shake

well. White ppt formed shows a diamide like urea. Urea oxalate test: 0.1g of the

substance shaken with 3ml of saturated solution of oxalic acid. White ppt

26

Benzamide Hydroxamic acid

O

ORNHCONH2 + HO.CH RNHCONH .CH O + H2O

indicates the presence of urea.

15. SULPHONIC ACIDS

Aromatic sulphonic acids:

i. These may be detected by fusion with alkali as follows. Mix about 0.5gm.of the

substance, 3gm. of potassium hydroxide and 5 drops of water in a nickel crucible.

Heat the crucible carefully, with occasional stirring, so that the mixture melts and

remains in the molten state for about 10 minutes. Cool the melt, add about 5 ml. of

water and stir the contents to dissolve the mass (warm, if necessary). Acidify the

solution - SO2 gas is evolved which may be detected by means of a filter paper

strip impregnated with acidified potassium dichromate solution.

ii. Treat the compound with phosphorus pentachloride and then with phenol in

alkaline medium. A crystalline derivative is obtained.

Ar-SO3H ArSO2Cl ArSO2-O-C6H5

The above formed sulphonyl chloride also reacts with ammonia to form

crystalline sulphonamide.

ArSo2Cl + NH2 ArSO2NH2 +HCI

16. THIOUREAS

i. Meat a small amount of the substance with 2 ml. of aq. NaOH to boiling for about

30 seconds. Cool and add one drop of CO2 Lead acetate-dark brown or black

colour.

RNH.CS.NR.R + 4KOH 2RNH2 + K2CO3 + K2S + H2O

K2S + (CH3COO)2 pb pbs black precipitate + 2CH2COOK

ii. Take a small amount of the compound in a test tube, add to it an alcoholic solution

of yellow mercuric oxide, and warm - a black precipitate of mercuric sulphide will

or formed.

27

PCl C6H5-OH

-HCl

Sulphonamide

RNH.CS.NH + HgO RNH.CO.NHR + HgS

iii. Fuse (melt) a small amount of the compound in a test tube, cool and dissolve the

product in water. Add aq. ferric chloride solution - a blood red colour will be

developed.

17. HYDROCARBONS

Although hydrocarbons have no general test, they can be detected by the

following tests.

i. Iodine test: Dissolve 0.2 gm. Or 2-3 drops of the substance in 5 ml. of benzene.

To this add 5 ml. of very dilute solution of iodine in benzene and shake; solution

remains violet.

ii. Friedel - Craft condensation test: (Only for aromatic hydrocarbons). Take

0.5gm. of anhydrous AICI3 in a dry test tube. Heat the test-tube when. AICI3

sublimes to deposit on the upper end of the tube. Now add 2-3 drops of a mixture

of equal amounts of the substance and chloroform. Allow this solution to come in

contact with aluminum chloride - appearance of red, orange, blue or green colour

due to the formation of triphenylmethane dyes indicates aromatic hydrocarbons.

Formalin Test

Sample + CCl4+HCHO+H2SO4

Observation red color with black ppt.

Esters:

1. Substance +1 drop of phenolpthalein + NaOH dorpwise while warming the pink

color disharges

2. Hydroxylamine test

Substaance + methanolic soln of hydroxylamine + HCl3 DROPS) + FEW

DROPS of Meth. Soln of KOH, boil, cool, add a drop HCl3 & acidity with CONC.

HCl

Purple / wine color ester confirmed

28

Part II

DERIVATIVES AND THEIR PREPARATIONS

Table of derivatives of the various classes of compounds

S. No Class of compounds Suitable derivatives

1. Acids Amides, Anilides, esters,bromo derivatives

2. Phenols Acetates, Benzoates, etc

3. Alcohols Acetates, Benzoates,

4. Aldehydes and Ketones 2.4 Dinitrophenylhydrazones, Phenyl

hydrazones, Oximes etc

5. Carbohydrates Osazones, Acetates, etc.

6. Amines Acetyl, Benzoyl, Bromo, etc.

7. Nitro compounds Polynitro, Amino and its derivatives.

8. Amides, Imides and Anilides Hydrolysis to acids, Nitro, picrates, etc.

9. Sulphonic acids Sulphonamides, Sulphanilides.

10. Hydrocarbons Nitro

DERIVATIVES OF CARBOXYLIC ACIDS

i. Amide: Shake the solution of 0.5 gm. of the acid with 1.5 ml. of phosphorus

pentachloride or thionyl chloride till the vigorous reaction ceases". Warm the

solution gently and then cool it. Now add cautiously nearly 10 ml of concentrated

ammonia solution, and when the vigorous reaction ceases, stir, cool and filter the

product (acid amide). Wash the acid amide with cold water, crystallize from water

and dry.

ii. Anilide or P-Toluidide: Shake the solution of 0.5 mg of the acid with 1.5 ml. of

PCl5 or SOCl2 till the vigorous reaction ceases. Warm the solution gently and then

cool it. Add nearly one ml. of aniline or p-toluidine (as the case may be) and shake

the reaction mixture vigorously. If necessary, warm and then cool. Filter off the

anilide or p-toluidide, wash it with cold water and crystallize it with alcohol and

dry.

Anilities or p- toluidide: may also be obtained directly from the acid itself.

29

One gram of the acid is relluxed gently under a very low flame for half an hour with

nearly two grams of the aniline or p-toluidine in a completely dry test tube. Cool the

reaction mixture, filter off the product and wash the anilide or p-toluidide with acid.

Crystallization may be accomplished by means of alcohol.

iii. Ester: Repeat as in acids

iv. For aromatic acids: Mix about 1g of the substance with 5ml of Br2 in glacial

acetic acid slowly, with constant stirring till yellow color develops. Shake well for

10-15 mts pour it into 50 ml of water with stiring. Filter the yellow crystals, wash

with water and recrystallise from dil AcOH.

DERIVATIVES OF ANHYDRIDES

i. Amide: Treat the compound with 10ml. of concentrated ammonia solution in a

glass stopper llask until a solid is formed, filter off the derivative, wash with water

and recrystallise from water or dilute alcohol.

ii. Anilide: (for monobasic acids): Meat a mixture of 1 ml. of aniline and 1 gm. of

the anhydride almost to boiling. Cool, add 3 ml. of water and stir the contents with

a glass rod. Recrystallise the product (anilide) from water or aqueous ethanol.

(RCO)2O + C6H5NH2 RCONHC6H5 + RCOOH

DERIVATIVES OF PHENOLIC HYDROXY GROUP

Benzoate: Dissolve 1.0 gm. of the phenol (or suspend 1.0 gm. of the amine) in 5 ml.

of acetone and add 2.5 ml. of benzoyl chloride Add 10 ml. of aq. NaOH gradually

with cooling and shaking, then add further 40 ml. of NaOH solution. Stopper the tube

or the flask and shake vigorously (if the flask or tube becomes hot it must be cooled

under tap Water) till the odour of benzoyl chloride has disappeared (which nearly

takes 20 minutes). The final solution should be alkaline to litmus.

30

O+NH3RCONH2

+

RCOOH

R.CO

R.CO

Acetate derivative: Take 1 g of the phenolic compound in a clean and dry test

tube; add 2.5ml of acetic anhydride and a drop of cone, sulphuric acid. Cork the tube,

shake it vigorously for 4-5mts and then transfer the mixture to 15ml of cold water,

Stir the contents with a glass rod till the oil solidifies. Filter, wash with water and

recrystallise from hot water.

DERIVATIVES OF ALCOHOLS

i. Acetate: Take one gm. of the alcohol, 0.5 g of fused sodium acetate and 5 ml. of

acetic anhydride in a conical flask. Shake and heat the mixture on a water bath for

1.4 hours. Transfer the warm solution into 75 ml. of ice cold water with vigorous

shaking. Keep the solution for some time and filter the product. Wash with water

and crystallize from alcohol.

ROH + (CH3CO)2O ROCOCH3 + CH3COOH

ii. Benzoate: Take I ml. of the alcohol, 10ml. of acetone, 5 ml of benzoyl chloride

and 50ml. of aqueous sodium hydroxide solution in a small flask. Cool, cork and

shake the flask vigorously till the odour of benzoyl chloride disappears. Filter off

the solid compound. Wash well with water and crystallize from alcohol.

DERIVATIVES OF ALDEHYDES AND KETONES

Oxime

For aldehydes and aliphatic ketones: Dissolve 0.5 gm. of hydroxylamine

hydrochloride and 0.5 gm. of the carbonyl compound, heat the mixture on the water

bath, add ethanol drop wise with shaking until a clear solution is obtained. Continue

refluxing until a sample of the reaction mixture gives a clear solution on adding to a

little 2N NaOH solution (1 to 2 hours). Cool the product when the derivative will

crystallize out, recrystallistion may be done with ethyl alcohol, aqueous ethanol or

petrol

31

CH3COONO

OH+(CH3CO)20 O C

O

CH3+CH3C

O

OH

C=O + NH2OH C = NOH + H2O

For aromatic and some cyclic ketones: Dissolve 1gm. of the ketone and 0.6

gm. of hydroxylamine hydrochloride in a mixture of 3 ml of ethanol and 1 ml. of

water. Reflux and Cool the reaction mixture, add about 20 ml. of water and shake,

filter the unchanged ketone (if any) and acidify the filtrate with dil. HCl (test with

blue litmus). Filter off the oxime.

Phenylhydrazone: It should be noted that phenylhydrazones of only the

aromatic carbonyl compounds are crystalline in nature while those of aliphatic

carbonyls are either oils or possess low m.p For aromatic carbonyl compounds,

dissolve 0.5 gm. of phenylhydrazine 0.8 gm. hydrochloride and 0.8 gm. of sodium

acetate in 5 ml of water. Add 0.2 to 0.4 gm. of the compound dissolved in alcohol to

the resulting solution. Shake the mixture and warm the solution on water bath for 10 -

15 mins, cool and filter of the derivate. Recrystallise the phenlhydrazone from dilute

ethanol, water or benzene,

C = O + H2N.HNC6HS C = N.HNC6H5

DERIVATIVES OF CARBOHYDRATES

i. Osazone: Take 0.5 gm of the powdered sample in a sugar clean test-tube. In

another test-tube dissolve 0.4 gm. of phenylhydrazine hydrochloride and.0.6 gm.

of crystalline sodium acetate in 4 ml of cold water and add this solution to first

test tube. Loosely cork the test tube, immerse it in a boiling water-bath with

periodical shaking, Cool the solution, filter the osazone precipitate and

recrystallise it from 50% alcohol.

ii. Acetate: Dissolve 0.5 mg. of the carbohydrate, 0.5 gm of powdered anhydrous

sodium acetate and 3 ml of acetic anhydride in 5 ml. of glacial acetic acid by

refluxing on a water bath. Further heat the solution for a period of two hours. Pour

cautiously the hot reaction mixture in 25ml/cold water and stir the solution

vigorously to decompose the excess of acetic anhydride. Filter off the product,

wash with cold water and recrystallise from alcohol.

32

Oxime

DERIVATIVES OF PRIMARY AND SECONDARY AMINES

(i) Acetyl derivative.

For primary amines: Suspend 0.5 gm of the amine in 0.15 ml. of water and

add 0.5 ml. of glacial acetic acid and 0.5 mol. of acetic anhydride drop wise with

saking If the mixture does not warm spontaneously, it is heated cautiously over a

small flame for 15 minutes. Cool the reaction mixture, if the oil does not solidify, stir

with a glass rod and cool in an ice bath. If on derivative separates, the acid in

neutralised with saturated sodium carbonate solution. Filter off the acetyl derivative

and recrystallise from water or aqueous ethyl alcohol.

For mononitroanilines: Take 1 mg. of the compound and 5 ml. of acetic

anhydride in a 100ml.wide mouthed flask fitted with a reflux condenser. Heat the

content to boiling for some time (2 minutes for m-and p-nitro and 10 minutes for a

nitroaniline), after refluxing, add 20ml. of boiling water. In case of para compound,

solid material separates out on the addition of water. Dissolve it by gradually adding

acetic acid with stirring and boil the contents in order to dissolve the oily material.

Cool, filter off the product and recrystallise from dil. Acetic acid.

For secondary amines: Warm a mixture of 0.5 gm. of the amine and 0.5 gm.

of acetic anhydride on the water-bath for 5-10 mins. Cool, add 3 ml. of water and stir

the mixture until the derivative is solidified.

It should be noted that sometimes the amine is resistant to acetylating, for

which sulphuric acid (as catalyst) may prove advantageous. One drop of concentrated

sulphuric acid is dissolved in 1 ml. of acetic anhydride, and one drop of this solution

is added to the reaction mixture before warming on the water bath.

ii) Benzoyl derivative: Suspend about 0.5 gm. of the compound in 10ml. of 5%

sodium hydroxide solution in a small conical flask. Add dropwise 1ml. of benzoyl

chloride, the flask should be well stoppered and shaken vigorously between additions

of the reagent. The reaction mixture should be kept cool throughout the addition.

Finally, shake the reaction mixture vigorously for 5-10 minutes and filter off the

product. Wash the derivative with water and recrystallise from alcohol.

33

DERIVATIVES OF NITRO COMPOUNDS

Nitro derivative:

Nitration with concentrated nitric acid: Add nearly 1 gm. of the compound

portion wise with shaking to 5 ml. of concentrated nitric acid density at room

temperature (cool under tap in case the reaction mixture tends to become warm). Stir

the mixture for 10 minutes and add some crushed ice when the product will be

crystallized out either on standing or on scratching the sides of the test-tube with a

glass rod. Filter off the product, wash with water and recrystallise.

DERIVATIVES OF AMIDES, IMIDES AND ANILIDES

i. Hydrolysis: Take 0.5 gm. of the compound and excess of 25% sodium hydroxide

solution in a conical flask fitted with reflux condenser. Reflux the contents until

all ammonia has been driven off (it takes about half an hour) and then cool. Add

concentrated hydrochloric acid drop wise till the reaction mixture is strongly

acidic and the acid separates out as a derivative. Filter and recrystallise from

alcohol.

RCONH2 + H2O RCOOH + NH3

RCONHR + H2O RCOOH + R NH2

ii. Xanthylamide: Add about 0.5 gm. of the substance to nearly 7 ml. of 7% solution

of xanthydrol in glacial acetic acid. Shake the contents well and then allow

standing for 10 minutes. If solid derivative is not obtained, heat the contents on a

water bath for about half an hour and then cool when solid xanthylamide is

obtained. Filter it off and recrystallise from acetic acid.

DERIVATIVES OF SULPHONIC ACIDS

i. Sulphonamide: Take 1 gm. of the dry sulphonic acid and mix it with 2 gm. of

phosphorous pentachloride. Heat the mixture on an oil bath at 150°C for about 30

minutes. When the reaction seems to be completed, cool the contents and treat

with 15ml. of cold water. Stir and wash the sulphonyl chloride twice with cold-

water by decantation. Now add 5ml. of the concentrated ammonia solution, with

stirring. Heat the reaction mixture on a water-bath for 5 to 10 minutes and then

34

cool. The amide will start crystallizing out, if not, evaporate the solution to

dryness on the water-bath. Recrystallise the derivative from water or aqueous

alcohol.

ii. Sulplianilmide: Prepare the sulphonyl chloride as above in (i) method. Dissolve it

in acetone and treat with 0.5 ml. of pure aniline dissolved in acetone together with

25ml. of deliver NaOH solution. Shake the mixture for 10 minutes, extract with

ether to remove excess of aniline. Acidy the product recrystllize from dil. Alcohol.

DERIVATIVES OF HYDROCARBONS

i. Nitration of halogeno hydrocarbons: Take 1 ml. or 1 gm. of the compound in a

dry test-tube, add to it 1.5 ml. conc HNO3 and 1.5ml. Conc H2SO4. Place the test-

tube in gently boiling water for 5 minutes with occasional shaking. Cool, add

10ml. of water and shake. Piker off the product, wash with cold water and

crystallize from alcohol.

ii. Picrate: Dissolve 0.5g of the compound (amine, phenol or aromatic hydrocarbon)

in minimum amount of ethanol. Add to it nearly 3ml of a saturated solution of

picric acid in ethanol. Warm the reaction mixture for one minute and then cool it

slowly. Filter off the picrate. Recrystallise the picrate of amines and phenols from

alcohol.

C10H8 + C6H2(NO2)3 OH C10H8C6H2(NO2)3 OH

35

SO2OH SO2Cl SO2NHC2H5

PCl5 H2NC6H5

Benzene sulphonyl chloride Sulphanilamide

Part III

LIST OF ORGANIC COMPOUNDS AND THEIR DERIVATIVES

m.pt:94°, α-Naptho

Colored crystalline solid. Slightly soluble in water. Readily soluble in NaOH,

alcohol, ether etc

1. No colour with neutral FeCI3 in H2O but gives white ppt.

2. Shake a small amounl of the compound with mixture having equal volume

of I2 and Kl and add excess of NaOH-violet colour, rapidly darkening and

followed by a precipitate.

3. Take a small amount of the compound in test tube and add to it 2ml. of aq

NaOH solution and one drop of chloroform. Warm a blue colour. This test

is also given by β-naphthol.

4. Take a small amount of the compound in a test tube, add to it 2 ml. of

NaOH, a drop of carbon tetrachloride and a pinch of copper powder.

Warm the contents- blue colour (distinction from β-naphthol).

Derivatives:

i. Benzoate M.P. 56°

ii. Picrate M.P. 189°

iii. Acetate M.P. 56°

iv. Dibromo M.P105°

v. P-Nitrobenzyl ether M.P. 140°

vi. Dinitrobenzoate M.P.217°.

36

vii. P-Tosyl M.P. 88°

Mp.2, Resorcinol

Pinkish white crystalline solid. Odourless Soluble in H2O, ether, alcohol and

chloroform.

1. With neutral aq. FeCl3 sol. It gives blue violet colour

2. Heat 1 c.c. of the aqueous solution of the original compound with 1 ml of

NaOH solution and a drop of chloroform till a definite red of violet red

colour is produced. Now fill up the test-tube with water-a red solution

appearing violet-red on shaking, giving no fluorescence on dilution

indicates resorcinol, while a violet-red solution changing to deep red,

yielding a green fluorescence indicates orcinol.

3. Heat a mixture of small amount (rice-grain) of phthalic anhydride and

twice this bulk of the original compound with 2 drops of conc. H2SO4 until

the mixture appears red-brown in colour. Cool and add a few drops of

water followed by NaOH solution gradually and with shaking until the

mixture is alkaline. take out 1ml. of this solution in a test-tube and fill up

the latter with water - a yellow-green fluorescence indicates resorcinol.

4. No ppt, with lead acetate solution

5. Apply general tests of polyhydric phenols.

Derivatives:

i. Dibenzoate M.P. 117°

ii. Dibenzenesulphonate M.P. 69°

iii. Di-p-toluenesulphonale M.P.80°

iv. 3,5-diitrobenzoate M.P.201°

37

v. P-Tosyl M.P.80°

vi. Dibromo M.P.I 12°

m.pt: 122°, βNapththol

Pink-brown coloured crystalline solid having Faint odour. Soluble in NaOH,

ether, alcohol and benzene; sparingly soluble in water.

1. No colour with neutral FeCl3

2. With titanic acid in conc. H2SO4 gives red colour.

3. Its solution in NaOH when warmed with chloroform gives a blue color

(Note that if CHCl3 is replaced by CCl4 no colour is obtained).

4. Phthalein test - faint green colour with some fluorescence.

5. Perform Test No.4 mentioned in α-napthol (M.P 94°).

Derivatives:

i. Acetate M.P. 70°

ii. Benzoae M.P.107.

iii. Oucrate M.P 156°

iv. P-Toluenesulphonate M.P. 125'

v. 3,5-Dinitrobenzoate M.P. 212°

vi. P.Tosyl M.P 125°

38

CARBOXYLIC ACIDS

133° Cinnamic acid

Shining cream colored crystals sparingly soluble in water and chloroform

soluble in alcohol and ether.

1. Take 2 ml. of the neutral solution of the compound, add an equal volume of aq

KMnO4 solution and shake-purple colour of permanganate is discharged with the

appearance of brown ppt. and bitter-almond like odour of benzaldehyde.

2. Take 2 ml. of the neutral solution of acid and add 2 ml. of alkaline KMNO4

solution. Heat and filter. Cool the filtrate while crystals of benzoic acid are

obtained.

Derivatives:

i. amide M.P.I470

ii. AnilideM.P. 153°

iii. p-ToluidieM.P.168°

iv. Dibromo M.P. 203°

v. p-Nitraobenzyl ester M.P 117°

vi. SBTM.P. 175°

101" Oxalic acid (Hydrated), (COOH)22H2O

Soluble in water.

1. Take about 2 ml. of the aq. soluion of oxalic acid, add 2 ml of glacial

acetic acid and 2-3 drops of aq. CaCl2 solution -white ppt. insoluble in

acetic acid but soluble in dil. HCI

2. Add 5 drops of conc H2SO4 to a small amount of the compound in a dry

test-tube and warm the contents gently by rotating the end of the tube over

a small flame and turn the mouth of the tube periodically to the flame

(characteristic blue flame of carbon monoxide.)

39

3. Heat the aq. Solution of the compound with acidic KMnO4 purple colour of

KMnO4 is discharged.

Derivatives:

i. Amide (di) M.P419°d

ii. Anilide (di) M.P.2450

iii. P-Toluidide M.P.2670

`

White shining cystals, sparingly soluble in cold water but fairly in soluble hot

water, alcohol benzene, acetone. CHCI3, and CCl4 Buffppt. with neutral aqueous

FeCI3 solution.

Derivatives:

(i) Amide M.P. 128°

(ii) P-Toluidide M.P. 158°

(iii) Anilide M.P. 164°

135° Acetyl salicylic acid (Aspirin)

Take 0.2 gm. of acid and 2ml. of dil. NaOH in a test tube. Boil the contents for

5 minutes. Cool, add dil. HCl -white precipitate of salicylic acid will be obtained.

40

121° Benzoic acid

COOH

O

COOH

CO

-CH3

Derivatives:

i. amide M.P. 138°

ii. anilide M.P 136°

iii. salicylic acid M.P. 155°

iv. P-Nitrobenzyl eser M.P. 140°

185° succinic acid, COOH CH2CH2COOH

Soluble in water, alcohol and acetone Sparingly soluble in ether.

1. Mix a rice-grain of the original compound with double.he amount of

resorcinol and 2 drops of cone. H2SO4. Gently heat the contents until the

mixture attains a red brown colour, cool, ad a few drops of water followed

by aq. NaOH till the solution becomes alkaline. Take out 1 ml. of this

solution into another test tube and fill he later with water (yellow green

fluorescence).

2. Derivatives: Amides M.p-260 ° c ; Anilides-M.P-228 °c

195°c, Plithalic acid

1. soluble in hot water and CHCI3 Sparingly soluble in ether.

2. Mix. A rice grain for the substance with double the amount of phenol in a

dry test-tube. Add 2 drops of cone. H2SO4 and heat gently till the mixture

attains red-brown colour. Cool, add few drops of water followed by

gradual addition of aq. NaOH solution with shaking till the solution

becomes alkaline-red colour due to phenolphthalein formation; the colour

is discharged on adding as acid.

3. Mix a rice grain of the substance with double the amount of resorcinol

Add 2 drops of conc H2SO4 and heat gently till the mixture attains red

brown colour. Cool, add few drops of water and then sq. NaOH till the

solution becomes alkaline. Take out 1 ml. of this alkaline solution in

another test-tube and fill up the later with water (yellow green

fluorescence.)

41

Derivatives:

i. Amide (di) M.P. 220°

ii. Anilide (di) M.P250°

iii. P-Toluidide (di) M.P. 201°

130° Phthalic anhydride

1. Insoluble in cold water but dissolves readily in hot water with

decomposition. Soluble in benzane and alcohol

2. Responds tests mentioned under phthalic acid.

3. Gives fluorescence test

Derivatives:

i. With zinc dust and acetic acid gives phthalide M.P. 73°

ii. Amide M.P. 149°

iii. Anil M.P. 210°

iv. (Anilic acid M.P. 170°

42

O

C

C

O

O

ALIPHATIC HYDROXY ACIDS

100° Citric Acid HCOOH. CH2OH (COOH)CH2COOH, Wt. 70

1. Soluble in water and alcohol but less in ether

2. Warm a small amount of the acid with conc H2SO4 evolution of CO and

CO2 takes place and the mixture turns into yellow solution without

charring. Heat the above solution for one minute, cool dilute with water,

add sodium hydroxide solution followed by sodium nitroprusside solution

intense red colour changing to violet on adding CH3COOH.

3. White crystalline precipitate on boiling the neutral solution with calcium

chloride solution (note that no ppt. is formed in cold)

4. Blue colour with β-naphthol in concentrated sullphuric acid

5. Perform test (4) mentioned on pg 109-110.

6. And few drops of AgNO3 solution to the aqueous solution of the

compound (a white ppt) in NH2OH and keep the test tube in boiling water

bath (a silver mirror is deposited on the walls of test-tube).

Derivatives:

i. Acetyl M.P115°

ii. Amide(tri) M.P 210°

iii. Anilide (tri) M.P.189°

170 Tartaric acid, HOOC.CH(OH).CH(OH).COOH, Eq.wt.75

1. Soluble in water and alcohol, Less soluble in ether.

2. Charring along with effervescences of CO and CO2 on heating with

concentrated sulphuric acid

3. Reduces ammonical silver nitrate solution (see test No. (6) in citric acid)

4. To acid solution in water, add one drop of FeSO4 solution, shake and add

one drop of H2O2 solution and then 2 ml. of NaOH solution (intense violet

43

colour.)

5. To acid solution and cobalt nitrate solution followed by excess of sodium

hydroxide solution no colour in cold, blue colour on warming, again

colourless on cooling.

6. Green colour with β-napthol in conc. Sulphuric acid the colour changes to

orange on dilution.

7. Take 3 ml. of neutral solution of acid, add 1 ml. of aq. CaCl2 solution and

shake vigorously heavy, write crystalline ppt. soluble on boiling with 1ml.

of glacial CH3COOH.)

8. To the aqueous solution add 5% solution of ammotmum vanadate, acidify

it with dil. CH3COOH (orange color).

9. Heat 0.2 gm. of acid, 0.2 gm. of resorcinol and 2 ml. of conc, H 2SO4 in a

test tube violet red colour appears.

Derivatives:

i. Amide (di) MP I95°d.

ii. Anilide (di) M.P.264°d.

iii. Acetyl M.P. 126°

PHENOLIC ACIDS

44

mol. wt 138. COOH M.P 158° Salicy lie acid.

1. Colourless needle type crystals. Sparingly Soluble in water for dissolves in

hot water, alcohol, ether and benzene.

2. Shake a small amount of the compound with cold water and then add a

drop of neutral aq. ferric chloride solution - violet colour.

3. Take a small amount of the compound in a dry test tube, add about 10

drops of methyl alcohol and 10 drops of conc. H2SO4. Heat the contents

gently, cool and pour these contents into a dish having 5 ml. of water

(odour of oil of wintergreen (methyl salicylate).

4. Add 1 ml. of cone. HNO3 to a small amount (0.2gm.) of the acid. Place the

test-tube in a boiling water-bath for 5 minutes; remove it and dilute with

water. Take out 2ml. of this yellow solution and dilute with water. Take

out 2ml. of this yellow solution (picric acid) make alkaline with aq. NaOH

and add 2 drops of ammonium sulphide. Place the test tube again in a

boiling water-bath forth minute (deep red colour owing to formation of

alkali salt of picric acid).

Derivatives:

i. Amide M.P 39°

ii. Anilide M.P 134°

iii. P-Toluidide m.p 1.156°

iv. SBT m.p l46°

v. Acetyl.p. 135°

45

ALDEHYDES

80 Vanillin

Slightly soluble in water. Soluble in organic solvents like ether, chloroform

benzene, etc red to violet colour with Fecl3

Derivatives:

i. 2,4 - Dinitrophenylhydrazone m.p. 270°

ii. Phenylhydrazone m.p 130°

iii. 2,4 Dinitrophenylhydazone m.p 260°

iv. Oxime m.p. 88°

KETONES

Benzil

Pale yellow. Insoluble in water. Place a pellet of KOH in a dry porcelain dish

laced on a heated Water bath. Now place 2 rice grains of the compound on the KOH

pellet and carefully pour 1 ml. of absolute alcohol from the side of the dish (deep

violet colour) Evaporate the contents -to- drynesse-remove any undissolved KOH,

and 1 ml of conc H2SO4.

46

CHO

CH3

OH

C

O O

C

Derivatives

i. Diphenyihydrazone m.p 225°

ii. 2,4 Dintrophenylthdrazone (di) m.p 189°

iii. Oxime (di m.p. 237°)

iv. Semicarbazone (di) m.p 243°

Benzoin

Yellow although pure benzoin is colourless insoluble in water. Sparingly

soluble in ether. Soluble in alcohol.

1. Take a small amount of the compound and add to it 1.ml of Fehling's solution

(equal volumes of No.l and No.2) and 1 ml. of water Boil the contents for 30

seconds - red ppt. of Cu2O

2. Take about 0.5 gm. of the original compound in a dry test-tube, add to it 1.25 ml.

of conc HNO3 (Avoid large amount of HNO3 which may cause nitrating of

benzoin). Place the test-tube in boiling water bath for about 10 minutes. Cool add

10ml, of water and shake till the red oil solidifies, Filter off pale yellow product

benzil, wash with cold water and crystallize from alcohol.

CARBOHYDRATES

146. Dextrose (d-glucose), CH2OH.(CHOH)4.CHO

1. Soluble in water and hot alcohol Insoluble in benzenes and ether.

2. Reduces Fehlings solution, Tollens reagent and Barfoed's reagent

3. Gives rapid furfural test, P.42

4. Apply test No (4) mentioned under maltose using twice the amount of lead

47

H

OH O

C

acetate (a salmon-pink or rose-pink colour)

Derivatives

i. Osazone m.p 205° formed on wanning for 48 minutes

ii. Penta-acetate m.p -112° B -134°

iii. Oxime m.p 137°

C.HYDROCARBONS

80 Naphthalene

White shining crystalline solid with characteristic odour. Insoluble in water

but soluble in alcohol, benzene and ether. Sublimes readily.

Derivatives:

1. Characteristic odour.

2. compound + CHCl3 + dry AICI3 Green colour.

i. Naphthalene picrate, m.p. 149°: place a small amount of the

powered naphthalene in a test-tube and dissolve it in 1 ml. of cold

benzene. Add 2 ml. of saturated solution of picric acid in benzene

and snake, filter off the precipitate; wash with few drops of cold

benzene and dry.

ii. Oxidation with conc. H2SO4 in presence of HgSO4 gives phthalic

acid,m.p.l95°.

48

SIMPLE AMIDES AND IMIDES

D. Acetamide,CH3CONH2

Soluble in water and alcohol; insoluble in either.

Derivatives:

i. Picratem.p. 107°.

ii. Anilidem.p.115°.

iii. Xanthylamide m.p.245°.

E. Benzamide C6H-CONH2

Sparingly soluble in cold water, soluble in hot water, alcohol and benzene,

sparingly soluble in either.

i. Mix a small amount of the substance with three times its bulk of dry soda

lime. Place this mixture into an ignition tube and heal-a better almond

odour of benzonitrile.

ii. Hydrolysis is benzoic acid m.p.121°: take 0.5 gm. of the compound

10ml.of aq. NaOH and some porcelain pieces in a 100 ml. flack fitted with

a reflex condenser. Roil (he contents under reflex condenser for 10mts.

Cool and acidity with cone. MCI. Cool and filter off the product Wash

with cold and crystallize from water.

Derivatives:

(i) anilide m.p. 160°

(ii) Xanthylamide m.p. 223°

132° urea, H2.N.CO.NH2

1. soluble in water, in excess of alcohol; insoluble in either.

2. Biuret test: Heat then cool the compound and then dissolve in warm aq.

NaOH sol. Add 1 to 2 drops of very very dil. Solution of CuSO4

Pink colour changing to violet and finally deep blue.

49

3. Xanth - hydrol test: Compound + 55% CH3COOH + 1ml. of 5% solution

of xanlh-hydrol in methyl alcohol the immediate formation

of ppt. indicates the presence of urea.

4. With sodium hypobromite solution Brisk effervescences of N2 and

CO2

5. Dissolve a small amount of urea in dil. HCL by heating. Cool, add about

3ml of NaNO2 solution add shake. Pass the vapours of this test - tube to

another tube having 3 ml of baryta water. Now close the mouth of the

baryta water tube with thumb and shake well -baryta water turns milky.

6. Urea nitrate m.p.163°: Heat a small amount of urea with water until a clear

solution is obtained. Cool add 2 ml. of conc. HNO3 and again cool. Filter

off the product, wash with cold water and dry.

Derivatives

i. Oxalate m.p. 171°

ii. With aniline hydrochloride it forms phenyl urea m.p. 147°

iii. N,N'-Diacetyl m.p 152°

iv. N.N'-Dibenzonyl m.p 218-220°d.

AMINO ACIDS (ALIPHATIC)

232 d-Glyeine, H2N.CH2. COOH

1. Soluble in 4 parts of water, insoluble in alcohol and ether.

2. Add one or two drops of FeCl3 to the aqueous solution of the compound-

(red colour).

3. Dissolve a small amount of the substance in water add to it 2 ml. of aq.

Copper sulphate solution - blue colour (very much deeper than the aq.

CuSO4 solution).

4. Take 2 ml. of the aqueous solution of the compound, add to it 2 drops of

phenolphthalein solution, 2 drops of aq. NaOH and 2 -3 ml. of neutralized

50

alcohol - disappearance of red colour.

Derivatives:

i. Preparation of benzoyl derivative (hippuric acid), m.p. 187°: Place 1 gm.

of the compound, 3 gm. of solid NaHCO3 and about 20 ml water in a 100

ml flask. Shake the contents well and then add 1.5 ml of benzoyl chloride.

Shake the uncolored flask vigorously till the odour of benzoyl chloride

disappears. Filter off Cool, filter off the product, wash well with cold

water and dry. Wash the solid product by stirring it with 10ml. of benzene

taken in a flask. Filter off the product, wash with benezene and crystallise

from water.

AMINO - PHENOLS

p-amino phenol M.P 184 °C

1. Soluble in excess water, sparingly soluble in ether.

2. Alkaline solution darkens rapidly in air.

3. Purple colour with FeCl3 or AgNO3

4. Dissolve a rice grain of the substance in 20 ml. of water. Take out nearly 5

ml. of this solution and add to it 1 ml. of aq. NaOH followed by 1 ml. of

saturated aq. Phenol solution. Shake the contents-deep blue colour within 1

minute.

5. Take a small amount of the substance in test and add to it 2 ml. of

dichromate mixture. Heat the contents to boiling (pungent odour of

benzoquinone)

6. Dissolve a small amount of the substance in 5 ml. of dil. HCl cither on

51

NH2

OH

p-amino phenol M.P 184 °C

shaking or on warming. Cool it, add 5 ml. canc. Sodium hypochlorite

solution (NaOH + Cl2 water) and shake yellow ppt. (quinone chloromide,

m.p. 85°).

Derivatives:

i. Diacetyl derivative, m.p. 150°. To a small amount of the substance add 3

ml. of acetic anhydride and heat the contents to boiling for 1 minute with

occasional shaking. Cool, add 5 ml. of water and shake. Filter off the

derivative, wash with cold water and dry.

ii. Monoacetyl m.p 168°

iii. Monobenzoyl m.p 216°

iv. Dibenzoyl m.p. 234°.

THIOUREAS

M.P 180°C Thiourea, H2N.CS.NH2

1. Soluble in cold water sparingly soluble in ether and alcohol.

2. Boil a small amount of the substance with NaOH—NH3 is evolved. To the

solution add 5 ml. water and a drop of FeCl3 (a blood red colour due to

formation of ferric thiocyanate is formed.)

3. Dissolve a small amount of the compound by heating with 2 ml. of dil.

Acetic acid. To the hot solution add 2 ml. of potassium Ferro cyanide

solution green colour changing to blue.

4. Heat a small amount of the compound on a small flame until the solid

melts. Continue heating for 5 seconds. Dissolve the residue by shaking

with 2 ml. of water and then add 2 ml. aq. FeCl3. Fill the test-tube with

water and shake (deep red solution.)

5. Its solution in NaOH gives black precipitate with lead acetate.

52

Derivatives:

i. On heating with benzyl chloride in alcohol it gives benzyliso - thiourea

hydrochloride m.p 174°.

ii. Xanthylm.p. 136°.

iii. Thiourea hydrochloride, m.p 136°.

AMINO SULPHONIC ACIDS

288° d Sulphanilic acid:

White Sparingly soluble in cold - water but soluble in hot water.

1. Add a pinch of substance to a solution of sodium bicarbonate -

effervescences of carbon, dioxide are evolved.

2. On diazotisation followed by coupling with alkaline α-napthol, it forms an

orange-red dye.

3. Dissolve a small amount of the substance in 2 ml of water by warming. To

the hot solution add bromine water with shaking until the solution gives

the yellow ppt.

4. Heat a small amount of the compound with 2ml of potassium dichromate-

sulphuric acid mixture to boiling (pungent odour)

5. Heat the compound with soda -4ime -(characteristic odour)

Derivatives:

i. 2,4,6-Tribromo m.p. 119°.

ii. p-Nitroaniline (obtained by treatment with cone. HNO3). M.P. 148°.

53

NH2

SO3H

iii. Sulphonamide, m.p. 200°.

iv. Sulphonanilide m.p.200°. CHO

ALDEHYDES

M.P 179° Benzaidehyde,

Odour of bitter almond. Sparingly soluble in water.

Derivatives:

i. oxime m.p. 35°.

ii. Phenylhydrazone m.p. 158°

iii. 2,4 - Dinitrophenylhydrazone m.p. 214°

KETONES

M.P 56° Acetone, CH3COCH3.

Miscible with water.

(i) With I2+ NaOH in cold gives iodoform m.p 119°.

Derivatives:

i. Phenylhydrazone m.p. 42°

ii. 2,4 - Dinitrophenylhydrazone m.p 128°.

iii. Semicarbazone m.p. 187°.

M.P 80° Methyl ethyl ketone. CH3COC2H5.

Miscible with water.

54

CHO

Derivatives:

1. 2,4-Dinitrophenylhydrazone m.p. 115°

2. Semicarbazone m.p. 135°.

AROMATIC PRIMARY AMINES

M.P 183° Anline, C6H5NH2

Soluble in 10 vol. of cold water but freely soluble in organic solvents.

1. With bleaching powder it gives purple colour.

2. Evil odour of phenylisocyanate on warming with ale. KOH and CHCl3

Derivatives:

i. Acetyl M.P. 113°.

ii. Benzyol M.P 160°

iii. Tribromo m.p 118°

iv. Azo - p- naphthol; m.p. 131°

QUESTIONS

1. What is the principle involved in the detection aromaticity?

2. Which types of compounds will give positive reaction with neutral Ferric

chloride?

3. What is carbylamine reaction?

4. What is diazotization? Which compound will undergo diazotisation?

5. Azo dye test-explain?

6. What happens when monocarboxyllic acids are treated with Ferric chloride?

7. How will you confirm the presence of Dicarboxylic acid?

8. How can you detect the presence of unsaturation?

55

9. Name some acidic organic compounds.

10. Name some basic organic compounds.

11. Name some neutral organic compounds.

12. Name some aliphatic and aromatic primary amines.

13. How can you distinguish aldehydes from ketones?

14. What is Molisch reagent?

15. What is Tollen's reagent?

16. Name some carbonyl reagents.

17. Name some easily oxidizable compounds.

18. Name some compounds which can reduce the carbonyl reagents.

19. What happens when aldehydes are oxidized with KMHO4?

20. Why phenol, naphthol are acidic in nature?

21. Why ammonia is basic in nature?

22. What happens if an ester is hydrolysed?

23. What is esterification?

24. Confirmatory test for urea

25. Identification tests for amino acid.

56

Part IV

PREPARATIONS

Exercise No.1. Preparation of Acetanilide from Aniline by acetyiation.

Requirements. Anline- 2.5 ml

Acetylating Acetic anhydride -2,5 mlMixture Glacial acetic acid-2.5 ml

PRINCIPLE:

Chemical reaction.

Amines can readily be acetylated to solid acetyl derivatives using acetylating

mixture. (Acetic acid is mixed due to the high cost of acetic anhydride). This reaction

is an eg for Nucleophilic substitution reaction Aniline acts as nucleophile and the lone

pair elecrons on the nitrogen atom attacks the carhonyl group of aceticanhydride and

the resuiting product is Acetanilide.

Procedure: Take 2.5 ml. of the aniline. 2.5 ml. of acetic anhydride and 2.5 ml.

of glacial acetic acid in a 250ml. conical flask, Shake the reaction mixture thoroughly

and then reflex it gently for 15 minutes using air condenser. Pour the hot mixture with

constant stirring to 200 ml. of ice cold water in a beaker. Filter the product and wash

with water. Recrystalise the curde acetanilide either from boiling water or dilute

acetic acid 20 ml. of acid 40 ml. of water).

Appearance : White shining Hakes

Yield : 4.5gms.

M.P. : 115°c

QUESTIONS

1. Explain the mechanism involved in acetylation.

2. Which is the nucleophile in this reaction?

57

3. How aniline is. Nucleophilic?

4. Indicate the anilide linkage.

5. Why is aniline aromatic?

Exerchcisc. 2: To prepare Aspirin (acetyl salicylic acid) from Salicylic acid by

acefylation.

Requirements: Salicylic acid 5 gms.

Acetic anhydride 7 ml.

Conc. Sulphuric acid 3-5 drops.

Chemical reaction:

PRINCIPLE: Salicylic acid is a phenolic acid. The phenolic group can easily

be acetylated using acetic anhydride. This is an eg of Nucleophilic substitution

reaction. Phenolic hydroxyl group of salicylic acid acts as nucleophile and the lone

pair of electrons on the oxygen atom attacks the carbonyl group of acetic anhydride to

form Aspirin.

Procedure: Take all the three chemical compounds in the given proportions in

a 250 ml. flask. Shake the mixture thoroughly and warm the reaction mixture at 50 -

60°c on a water - bath with continuous stirring. Allow the reaction mixture to cool

and add nearly 125 ml. of-water, stir thoroughly and filter the product. Recrystallise

the product from 50% alcohol or 50% acetic acid or hot water.

Appearance Colourless needles

Yield 5 gms.

M.P 136-137°C

58

QUESTIONS

1. Explain the mechanism?

2. Which is the nucleophile?

3. Use of Aspirin

4. Identification tests for aspirin

Exercise No.3. To prepare 2,4,6 - Tribromoaniline from Aniline by bromination.

Requirements

Aniline 2ml.

Glacial acetic acid 15 ml.

Bromine in glacial acetic acid 3 ml in 10 ml of

Ice glacial acetic acid

Chemical reaction:

PRINCIPLE: Benzene does not react appreciably with Bk but the presence of

activating groups like NH2 on the ring can activate the substitution, can easily form

bromo drrivatives, when treated with a solution of Br2 in acetic acid. This is an eg of

Electrophilic substitution reaction. Since- NH2 is an ortho, para director the incoming

bromonium ion (clcehophele) is directed to form symmetrical tribromo aniline

Procedure. Take 2 ml. of aniline and 1.5 ml. of glacial acetic acid in a conical flask.

Place the Bask in ice bath and add to it 8.4 ml. of bromine water in 10 ml. of glacial

acetic acid dropwise with constant stirring through a burette or separating funnel.

Pour the reaction mixture to a beaker having excess (100ml) of water. Filter the

product wash with water and reerystallise from alcohol or rectified spirit.

59

Appearance Colourless shining 1ong needles

Yield 5 gm.

M. P. 120°C

QUESTIONS

1. Explain the mechanism of reaction

2. Which is the electrophile?

3. What type of group is-NH2?

4. Explain how benzene is more stalte?

Exercise No.4 To prepare p-Bromoaeetanilide from Aeetanilide by tromination.

Requirements:

Aeetanilide 2 gm.

Glacial acetic acid 15 ml.

Bromine in glacial acetic acid 3 ml. of bromine in 10 ml. of glacial

acetic acid.

Chemical Reaction:

PRINCIPLE: The anilide group present in aeetanilide. is a moderate

activating group which directs the incoming bromonium ion to ortho and para

positions. Practically only a little amount of ortho product is formed because of steric

hindrance of the bulky functional group. The formed ortho product is removed during

recrystallisation because it is completely soluble in alcohol or rectified spirit. This

reaction is also an eg-for Electrophilic substitution.

60

Procedure: Dissolve 2 gm. Of the aeetanilide in 15 ml. of glacial acetic acid

in 250ml. flask. Add 31 ml. of bromine dissolved in 10 ml. glacial acetic acid from a

burette or a separating funnel to the aeetanilide solution drop by drop with continuous

stirring. Allow the reaction mixture to stand for half an hour. Pour the contents to a

beaker having 250 ml. cold water. Filter the product, wash with cold water, dry and

recrystallise from alcohol or rectified spirit.

Appearance White crystalline compound

Yield 2.5 gm.

M.P. 167°C

QUESTIONS

1. Explain the mechanism of reaction.

2. Which is the electrophile?

Exercise No.5 To prepare Phenylazo - p* - naptho£from Aniline by diazotization

followed by coupling reaction.

Requirements:

Aniline 2ml

Cone. Hydrochloric acid 4 ml

Sodium nitrite 1g

β-Napthol 1.95 g

Sodium hydroxide 10% 11ml

Ice

PRINCIPLE: Aniline is an aromatic primary amine which can undergo diazotisation

to form benzene diazonium chloride in presence of sodium nitrite and con HCl. This

in turn undergoes coupling reaction with 2-napthol phenyl azo2-naphthol.

PROCEDURE: Dissolve 1.2ml of aniline in 4ml of con HCl and 8ml of water in a

conical flask Diazotise by addition of solution of 1g of sodium nitrite in 5ml of water.

61

Prepare the solution of 1.95g of 2-naphthol in 11ml of 10% NAOH in a 250ml beaker

cool the solution to 5°C immersion in ice bath or by direct addition of 10 -15g of

crushed ice. Stir the naphthol solution vigorously and add the cooled Diazonium

chloride solution very slowly. Red colour develops and red crystals of phenyl azo 2-

naphthol separates out. When all the solution has been added allow mixture to stand

in ice bath for 10mts with stirring. Filter the solution wash well with water and drain

thoroughly. Recrystallize the product from glacialacetic acid.

Appearance Deep shining red crystals

Yield 3.5 g

M.P 131 c

QUESTIONS

1. Explain Diazotisation.

2. How does nitrous acid is generated?

3. Why nitrous acid should be generated in situ?

Exercise No: 6 Determination of Mixed Melting Point

Aim: To determine the mixed melting point of the following mixtures and to report on

the purity of (I) and to report whether the product is formed in (2)

1. Benzoic acid & 2-Naphthol

2. Aspirin and Anilide of Aspirin

PRINCIPLE: Presence of impurity generally decreases the melting point so if

two compounds having very close melting points are mixed the melting point of the

mixture will considerably be lower than that of either of the two compouns. So the

melting point determination helps to ascertain whether the compound is pure or not.

In some cases the melting point of the compound is very close to its derivative

so it becomes very difficult to ascertain by means of melting point that whether the

product is formed or not. In such cases, the derivative should be mixed with the

original compound and the mixture should be subjected to melting point

62

determination. If the melting point of the mixture is very low than that of either of the

components it is ascertained that the derivative is formed, because if the derivative

were not been formed the mixture will have the same melting point as the original

compound.

PROCEDURE: Close one end of the capillary tube, by holding it in the edge

of a flame continuously rotating till it is sealed. Introduce nearly 0.5g of the

completely dried and finely powdered compound by thrusting the open end of the

capillary tube into a small heap of the compound and tapping with the sealed end of

the tube on the bench. Place the capillary tube inside the electrically heated melting

point apparatus and note down the melting point. Determine the melting point of pure

Benzoic acid & 2-Naphlhol and mixture of the two by placing the tubes beside each

other inside the apparatus. Determine the melting point of Aspirin and the product

expected to be Anilide of aspirin and for the mixture of the two compounds. Report

Melting point of Benzoic acid =

Melting point of 2-Naphthol =

Melting point of Benzoic acid & 2-Naphthol =

Hence the given sample is PURE/IMPURE =

Melting point of Aspirin =

Melting point of Anilide of Aspirin =

Melting point of mixture =

Exercise No 7: Stereo Models of Organic Compounds

Aim: To construct the bail and stick stereo models of Methane, Ethane, ethylene

Acetylene, Acetone and Benzene and comment on the shape, structure, bond angle,

bond length etc.

PRINCIPLE: Carbon atom can exist in three hybridized states depending on the

number of atoms attached to it.

63

Carbon atom is SP3 hybridized if attached to 4 atoms or groups.

Carbon atom is SP2 hybridized if it is attached to 3 atoms or groups.

Carbon atom is SP hybridized if it is attached to 2 atoms or groups.

SP3 hybridized carbon is tetrahedral in shape SP2 hybridized carbon is trigonal

in shape and SP hybridized carbon is planar. So depending on the number of atoms

attached to the carbon atom the stereo model can be build for better understanding of

the molecular geometry.

PROCEDURE: Carbon atom is black colored and hydrogen atom is white

coloured. White sticks are used to represent the bonds between the atoms. Three

different carbon atoms are available to provide tetrahedral, trigonal and planar

arrangement. Select the carbon atom according to the number of atoms attached to it.

Build the model by inserting the sticks into the holes provided in the corresponding

atom. Finally report the shape, Molecular orbital picture of the molecule, type of

hybridization of carbon, Number of sigma bonds and pi bonds, bond length and bond

angle.

QUESTIONS

1. Molecular formula for Methane, Ethane, ethylene and acetylene

2. State of hybridization of carbon in Methane Ethane and Acetylene.

3. What is the valency of carbon, oxygen, nitrogen, hydrogen?

4. Define valency.

5. Define bond angle, bond length.

6. Define orbital, molecular orbital.

7. Why acetylene is more reactive?

8. Why bond length in alkenes, alkynes is, less than alkanes?

9. Define atomic weight, molecular weight. Equivalent weight and atomic

number.

10. IUPAC name for Acetylene.

64

Dibenzal acetone by Claisen's - Schmidt condensation

AIM

To prepare dibenzal acetone by claisen's - Schmidt condensation

PRINCIPLE

Aromatic aldehydes condense with aliphatic ketones or with mixed alkyl- aryl

ketones in the presence of aqueous alkali to form a, β- unsaturated ketones.

In the preparation of dibenzalacetone 2 molecules of benzaldehyde condenses

with 1 molecule of dibenzal acetone. This reaction is called claisen's condensation.

PROCEDURE

1. In a 150ml conical flash place a cold solo of 5.0g of NaOH pellets in 50ml

of H2O and 40ml of alcohol.

2. Whilst swirling the contents of the flash, add a mixture of 5.1ml of pure,

redistilled C6H5CHO and 1.9ml of A.R. acetone. Shake frequently and

maintain the temperature at 20-25c for 15min by immersion of the flask in

a bath of cold H2O.

3. Filter off the precipitated dibenzal acetone at the pump and wash it in cold

water to eliminate the alkali as completely as possible.

4. Crude precipitate is recrystallized for ethyl acetate or Rectified spirit. Pure

dibenzal acetone [A yellow crystal solid]

NOTE

Sufficient alcohol is employed to dissolve the benzaldehyde and to retain the

initially formed benzal acetone in solution until it has had time to react with the

second molecule of benzaldehyde.

65

Preparation of Benzanilide

Aim

To prepare and submit Benzanilide

Principle

Acylation of an Aromatic 1/2 amine may be readily achieved by using an acid

chloride.

In general, Benzoyiation of aromatic,amines finds less application than

acetylation in preparative work, but the process is often employed for the

identification & characterization of amines. In the schoyen - Baumen Method of

Benzoylation, the amine, or its salt is dissolved (or) suspended in a slight excess of 8 -

15 % NaOH & soln a small excess of benzoyl chloride is then added & the mixture

vigorously shaken in a stoppered vessel [Benzoylation proceeds smoothly & the

sparingly soluable benzoyl derivative separates as a sold.

Procedure

Suspend 1 g (1ml) the substance in 20 ml of 5% NaOH soln in a Well - corked

boiling tube (or) small concial flask, & add 2 ml of Benzoyl chloride 0.5 ml at a time

with constant shaking, and cooling in water if necessary shake vigorously for 5-10

min until the odour of benzoyl chloride has disappeared. Make sure that the mixture

has an Alkaline reaction. Filter off the solid benzoyl derivative) wash it with a little

cold water & Recrystallise it from ethanol (or) dil

66

SYNTHESIS OF BENZPPHENON OXIME

Aim

To prepare and submit Benzophenone Oxime.

Principle

Benzpphenone condenses with Hydroxylamine in the presence of excess of

NaOH soln to yield the oxime.

(C6H5)2 CO + H2NOH

(C6H5)2 C=N-OH + H2O.

Procedure

In a 100ml RB Flask filed c a Reflux condenser place 5 gm of Benzophenone,

3 gm of Hyproxylamine HCl, 10ml of ethanol & 2 ml of H2O, To the resulting

mixture now add with shaking &.in portions 5.6 gm of solid NaOH taking care that

the reaxn does not become too vigorous Jn so cool the flask under tap water. After the

addition of NaOH is complete heat the flask under Reflux-for 10 min. cool and pour

the contents of the flask in a beaker containing a soln of 15 ml of cone. HCl in 50 ml

H2O. Filter the precipted Oxime & wash with cold water. Recrystallizerthe product

from methanol.

M.P=>140 - 142°C

Yield = 5 gms.

67