Students of gurunanak college of pharmacy,Nagpur

1. URUNANAK COLLEGE OF PHARMACY
NAGPUR
"THE ATOM FAMILY "
GROUP -
3RD SEM
PRESENTED BY :-
Kunika Chopkar
Nikita Lodhi
Sanjana Pahade
Roshan Watari
Samiksha KalePRESENTED TO :- Res.. Pradnya Gondane Mam
TOPIC:- QUALITATIVE TESTS FOR PHENOLS

3. Solubility of phenols :-
. The solubility of phenol in water is governed by the hydroxyl group present.
. The hydroxyl group in phenol is involved in the formation of intermolecular hydrogen
bonding.
. Thus, hydrogen bonds are formed between water and phenol molecules which make
phenol soluble in water.
. However, the aryl group attached to the hydroxyl group is hydrophobic in nature.
. Thus, the solubility of phenol decreases with the increase in the size of the aryl group.

4. PHENOLS
. Aromatic compounds containing one or more OH groups directly attached to
carbon of benzene ring are called phenols.
. Simplest phenol is carbolic acid.
. Term phenol is derived from an old name of benzene
- PHENE
. Phenyl = C6H5

5. Ferric Chloride Test:
complex. Most phenols give dark coloured solution.
The chemical reaction is given below.
6C H OH + F
eC→l [Fe(C H O) ] (violet colour complex)+ 3HCl + 3H
esol
Phenol, resorcinol, Ortho cresol, Para cr Violet or blue colouration
Catechol Green colouration
Hydroquinone Violet or transient blue color
Pyrogallol Blue rapidly changing to red

6. Libermann’s Test:
l and
lex is
ol is
dium
Phenol reacts with concentrated sulfuric acid and
sodium nitrite forms a yellow colour quinone
monoxime complex. With excess of pheno
sulfuric acid a deep blue indophenol comp
formed. On dilution a red colour indophen
formed which turns to deep blue colour so
salt
solution of indophenol on treatment with sodium
hydroxide.
Note: This test is given by phenols which contain a
free para position.

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9. Phthalein Dye Test:
Phenol on heating with phthalic anhydride in the
presence of concentrated sulfuric acid forms a
colourless condensation compound called
phenolphthalein. On further reaction with dilute sodium
hydroxide solution gives a pink colour fluorescent
compound called fluorescein. Characteristic
colours are produced by different phenolic compounds
which can be viewed under white
background.

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11. Analysis of phenols :-
. The most characteristics property of phenols is their particular degree of
acidity. Most of them are stronger acids than water but weaker acids than
carbonic acid. Thus, a water in-soluble compound that dissolves in
aqueous sodium hydroxide but not in aqueous sodium bicarbonate is most likely
a phenol.
. Many (but not all) phenols form coloured complexes with ferric chloride.
. Phenols are even identified through bromination products and certain
esters and ethers.
. Carboxilic acid > Phenol > Water > Alcohol

12. Spectroscopic analysis of phenols (structure
elucidation):-
Infrared. As can be seen in Fig. 24.2 (p. 806), phenols show a strong, broad band due to
0-H stretching in the same region, 3200-3600 cm", as alcohols.
O-H stretching, strong, broad
Phenols for alcohols), 3200-3600 cm-1
Infrared spectrum of p-cresol.

13. . Phenols differ from alcohols, however, in the position of the C-O stretching band.
C-O stretching, strong, broad
. Phenols, about 1230 cm-1 Alcohols, 1050-1200 cm-1
. Phenolic ethers do not, of course, show the O-H band, but do show C-0 stretching
C-O stretching, strong, broad
. Aryl and vinyl ethers, 1200-1275 cm, and weaker, 1020-1075 cm"¹
. Alkyl ethers, 1060-1150cm
. NMR. Absorption by the O-H proton of a phenol, like that of an alcohol , is affected by the
degree of hydrogen bonding, and hence by the temperature, concentration, and nature of
the solvent. The signal may appear anywhere in the range 4-7, or, if there is
δ
intramolecular hydrogen booding, still lower: 6-12.
δ
. CMR. The OH of phenols exerts the usual effect of an electronegative substitute.

14. Confirmatory test:-
Carboxylic acid dissolve aq.sodium bicarbonate Fruity smell
Bubble of gas
CO2
Phenol no reaction with sodium bicarbonate no fruity smell
solution

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