Question

An acid halide $\left( {\rm{X}} \right)$ reacts with excess of Grignard reagent. The product \[\left( {\rm{Y}} \right)\] can be:

Answer 1

Hint: The product can be deduced by using the understanding of the mechanism of the reaction between an acid halide and Grignard reagent.

Step by step answer: Grignard reagent is an organo-metallic compound with a general formula ${\rm{RMgX}}$ in which an alkyl group $\left( {\rm{R}} \right)$ is attached to magnesium and there is a halide $\left( {\rm{X}} \right)$ present as well. In ${\rm{R}} - {\rm{MgX}}$ bond is covalent but due to Electronegativity difference, it is polar and ${\rm{RMg}} - {\rm{X}}$ bond is ionic in nature. This gives rise to charge separations as ${{\rm{R}}^{\delta - }}{\rm{M}}{{\rm{g}}^{\delta + }}{{\rm{X}}^{\delta - }}$.
The nucleophilic carbon centre makes it highly useful as we will see further in the reaction with acid halide.

An acid halide can be represented by a general formula \[{\rm{RCOX}}\] where a carboxylic proton has been replaced by a halogen. The presence of a carbonyl group helps in having an electrophilic carbon centre as $\left( {{\rm{C}} = {\rm{O}}} \right)$ bond is polar and electrons are pulled mostly by oxygen making carbon, electron deficient.
In a reaction of acid chloride with excess Grignard reagent, nucleophilic carbon will attack on the electrophilic and the subsequent hydrolysis will give an alcohol as follows:

As we can see that the product contains two alkyl groups from the Grignard reagent that must be the same and one original that may or may not be the same.

Now, as in the given options, only one has the same substituents, in fact all of them are the same whereas all others have different substituents.
So, the product \[\left( {\rm{Y}} \right)\] can be:

Hence, the correct option is A.

Note: The normal reaction of acid chloride with Grignard reagent would give ketone only; it is only when Grignard reagent is in excess that a tertiary alcohol is produced.