Assertion (A): When methyl benzoate is treated with only 1 equiv of $CH X_{3} MgBr$ , acetophenone cannot be obtained as the main product. Reason (R): Acetophenone is more electrophilic than methyl benzoate and reacts faster with $CH X_{3} MgBr$ .

ABoth A and R are true and R is the correct explanation of A
BBoth A and R are true but R is not the correct explanation of A
CA is true but R is false
DA is false but R is true

Answer: A

The ester carbonyl is stabilised by resonance donation from the OR oxygen, but the ketone has no such donor. Once acetophenone forms it competes successfully for the Grignard, so a mixture of unreacted ester and tertiary alcohol results. A and R are true and R explains A: option A.

Practice Organic Reaction Mechanisms I: Nucleophiles and Carbonyl Addition More on Nucleophilic acyl substitution of carboxylic acid derivatives

Previous questionNext question

Assertion (A): When methyl benzoate is treated with only 1 equiv of CHX3​MgBr, acetophenone cannot be obtained as the main product. Reason (R): Acetophenone is more electrophilic than methyl benzoate and reacts faster with CHX3​MgBr.

Answer: A

More questions on Nucleophilic acyl substitution of carboxylic acid derivatives

Assertion (A): When methyl benzoate is treated with only 1 equiv of $CH X_{3} MgBr$ , acetophenone cannot be obtained as the main product. Reason (R): Acetophenone is more electrophilic than methyl benzoate and reacts faster with $CH X_{3} MgBr$ .