Question

Which of the following pair cannot be separated by ${\mathrm{NaHSO}}_3$?

• A.
• B.

  

• C.

  

• D.

Answer 1

The correct option is C

Explanation for correct option

(C)${\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{COC}}_2{\mathrm{H}}_5$

• Sodium Bisulphite reacts with carbonyl compounds generally with aldehydes and ketones having a small aliphatic chain.
• It generally does not react with aromatic ketones due to steric hindrance posed by the large-sized benzene ring.
• Nucleophilic addition is unfavorable in the case of heavy substituents.
• In option C, two large ethyl group is present. Because of increased steric hindrance, the incoming nucleophile cannot react.

Explanation for incorrect options

(A)

The reaction of ethanal with ${\mathrm{NaHSO}}_3$ is as follows:-

• As shown in the above reaction, similarly (B), and (D) also reacts with ${\mathrm{NaHSO}}_3$.
• Hence, options (A), (B), and (D) are incorrect.

Hence, option (C) can not be separated by ${\mathrm{NaHSO}}_3$.