i. Acetophenone and Benzophenone ii. Phenol and Benzoic acid

Question

Give simple chemical tests to distinguish between the following pairs of compounds:
i. Acetophenone and Benzophenone   ii. Phenol and Benzoic acid
iii. Benzoic acid and ethyl benzoate      iv. Benzaldehyde and acetophenone
v. Ethanal and propanal

Answer 1

Acetophenone and Benzophenone: Acetophenone being a methyl ketone when treated with NaOI (I₂ / NaOH) gives yellow precipitate of iodoform whereas benzophenone does not.

ii. Phenol and Benzoic acid: Phenol is a weak acid it does not react with weak base NaHCO₃ whereas benzoic acid is a strong acid. It reacts with NaHCO₃ to form a sodium salt alongwith evolution of CO₂.

iii. Benzoic acid and ethyl benzoate: Benzoic acid is a carboxylic acid and reacts with NaHCO₃ to form a sodium salt alongwith evolution of CO₂. Ethylbenzoate is an ester. It does not react with NaHCO₃.

iv. Benzaldehyde and acetophenone: Benzaldehyde being an aldehyde reduces Tollen’s reagent to shining silver mirror whereas acetophenone being a ketone does not.

v. Ethanal and propanal: Ethanal contains CH₃CO group. Hence on treatment with NaOI (I₂ / NaOH) gives yellow precipitate of iodoform whereas propanal does not.