Answer :
The combination of a Grignard reagent and a carbonyl compound needed to synthesize a specific alcohol depends on the structure of the alcohol desired. Aldehydes react with Grignard reagents to form secondary alcohols, while ketones yield tertiary alcohols. The reaction is a nucleophilic addition where the carbanion from the Grignard reagent adds to the electrophilic carbonyl carbon. Therefore the correct option is d).
To identify the combination of carbonyl compound and Grignard reagent for synthesizing a specific alcohol, one must consider the structure of the alcohol that the reaction is expected to produce. The reaction of a Grignard reagent with a carbonyl compound typically results in the formation of an alcohol after the workup procedure. The type of alcohol (primary, secondary, or tertiary) depends on the specific carbonyl compound used. When working with esters, the Grignard reagent reacts twice, effectively adding two alkyl groups to form a tertiary alcohol. However, with aldehydes and ketones, the addition of one Grignard reagent molecule results in secondary and tertiary alcohols, respectively.
For example, reacting a Grignard reagent, represented as RMgBr, with an aldehyde will yield a secondary alcohol after the workup, and reacting the same Grignard reagent with a ketone will yield a tertiary alcohol post-workup. The choice of the Grignard reagent depends on the desired R group to be appended to the carbonyl. The overall process is a nucleophilic addition of the carbanion equivalent from the Grignard reagent to the electrophilic carbon in the carbonyl group.
