Ethyl benzoate is heated with aqueous sodium hydroxide solution. Which of the following are formed before the reaction mixture is acidified?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Sodium benzoate and ethanol
Ethyl benzoate is the ester of benzoic acid and ethanol. On hydrolysis the ester splits back into these two parts. In basic hydrolysis the acid part is obtained as its salt, the carboxylate, because the alkali neutralises it:
\( \displaystyle \ce{C6H5COOC2H5 + NaOH} \xrightarrow{\Delta} \ce{C6H5COONa + C2H5OH} \)
Benzoic acid itself appears only when the solution is acidified:
\( \displaystyle \ce{C6H5COONa + HCl -> C6H5COOH + NaCl} \)
Why the other options are incorrect
Option (1) Benzoic acid and ethanol — Incorrect.
These come directly from acidic hydrolysis: \( \ce{C6H5COOC2H5 + H2O} \xrightarrow{\ce{H3O+}} \ce{C6H5COOH + C2H5OH} \).
In sodium hydroxide the acid stays as sodium benzoate until acid is added.
Option (3) Sodium benzoate and sodium ethoxide — Incorrect. The ethoxy part of the ester is set free as ethanol. Sodium ethoxide is formed when ethanol reacts with sodium metal, not in aqueous sodium hydroxide.
Option (4) Benzyl alcohol and sodium ethanoate — Incorrect.
These would come from benzyl ethanoate, \( \ce{CH3COOCH2C6H5} \), the ester of ethanoic acid and benzyl alcohol.
Ethyl benzoate is made from benzoic acid and ethanol, so it cannot give them.
NCERT (2026-27 edition):
8.7 Methods of Preparation of Carboxylic Acids – “6. From esters: Acidic hydrolysis of esters gives directly carboxylic acids while basic hydrolysis gives carboxylates, which on acidification give corresponding carboxylic acids.”