Answer :
Final answer:
Benzophenone serves as a reagent in the preparation of triphenylmethanol via the Grignard reaction with bromobenzene, and the Grignard adduct formed is phenylmagnesium bromide. so,the correct option is:(b) It serves as a catalyst; the Grignard adduct is phenylmagnesium bromide.
Explanation:
In the preparation of triphenylmethanol via the Grignard reaction with bromobenzene and magnesium, benzophenone serves as a reagent, not as a solvent, catalyst, or stabilizer. The role of benzophenone in this reaction is to be the electrophilic carbon source that reacts with the Grignard reagent, which is phenylmagnesium bromide, to form triphenylmethanol. The Grignard reagent is formed when the bromobenzene reacts with magnesium metal in the presence of a suitable ether solvent, such as diethyl ether or THF, leading to the formation of the organomagnesium compound, phenylmagnesium bromide. This compound contains a carbon-magnesium bond and behaves as a carbanion nucleophile which can then attack the electrophilic carbonyl carbon of benzophenone to form the corresponding alcohol after working up with an acid.
In the preparation of triphenylmethanol via a Grignard reaction with bromobenzene and magnesium, benzophenone serves as a catalyst. The Grignard reagent, phenylmagnesium bromide, is formed by the reaction between bromobenzene and magnesium in the presence of benzophenone. Benzophenone acts as a catalyst by facilitating the initiation of the Grignard reaction. It forms a radical species upon exposure to light, which reacts with magnesium to generate magnesium radicals. These magnesium radicals then react with bromobenzene to form the Grignard reagent, phenylmagnesium bromide.
