How the following pairs can be distinguished ?
(i) Phenol and benzoic acid.
(ii) Phenol and glycerol.
(iii) Phenol and ethyl alcohol .
(iv) Phenol and salicyclic acid.
(v) 1-Phenylethanol and 2-phenylethanol.
(vi) Phenol and benzyl alcohol.
(vii) Phenol and acetic acid.
(viii) Phenol and cyclohexanol.

Answer

(a) Phenol gives violet colour with ferric chloride solution, benzoic acid doen not.
(b) Benzoic acid gives effervescence with with aqueous `NaHCO_(3)` solution, phenol does not.
(ii) (a) Phenol gives violet colour with aqueous ferric chloride solution while glycerol does not.
(b) Glycerol on heating with `KHSO_(4)` gives a pungent odour compound, acrolein , the aqueous solutionof which gives Schiff's reagent test while phenol does not.
(iii) (a) Phenol gives violet colouration with `FeCl_(3)` aqueous solution, ethyl alcohol does not.
(b) Ethyl alcohol gives iodoform test, phenol does not.
(iv) Phenol when heated with phthalic anhydride in presence of 2-3 drops of conc. `H_(2)SO_(4)` forms phenollphthalein which gives pink colour with NaOH solution. This test is not given by salicyclic acid.
Sallicyclic acid give efferversences with `NaHCO_(3)` solution while phenol does not.
(v) -Phenyl ethanol `(C_(6)H_(5)-CHOH-CH_(3))` having `(-CHOH-CH_(3))` group gives iodoform test while 2-phenyl ethanol `(C_(6)H_(5)-CH_(2)CH_(2)OH)` does not.
(vi) (i) Phenol gives violet colour with aqueous `FeCl_(3)` solution while benzyl alcohol does not.
(ii) On oxidation benzyl alcohol gives benzoic acid while phenol forms a coloured complex.
(viii) With NaOH ( and not with `Na_(2)CO_(3), NaHCO_(3)` or `CH_(3)COCl)` only phenols dissolve in alkali to form phenoxide.