Question

Among the given compounds, the compound which is most susceptible to a nucleophilic attack at the carbonyl group is :

• A. $C{H}_{3}CHO$
• B. $C{H}_{3}COCl$
• C. $C{H}_{3}COOC{H}_3$
• D. $C{H}_{3}COOCOC{H}_3$

Answer 1

Answer: (B)

We know the following facts:
1. Weaker bases are better leaving groups.
2. Strong acids have very weak conjugate bases.
Here, $HCl$ is a very strong acid.
So, the chloride ion is a very weak base as compared to others.

Hence, it is the best leaving group in nucleophilic acyl substitution.

Besides, the $Cl$ group also activates the carbonyl group towards nucleophilic substitution reaction due to its $-I$ effect.

Therefore, $C{H}_{3}COCl$ is most susceptible to nucleophilic attack at the carbonyl group because it will show fastest rate of reaction.