Benzonitrile on reaction with a reagent in dry ether followed by hydrolysis forms benzophenone along with ammonia and hydroxymagnesium bromide. Identify the reagent used in above transformation.

Step-by-step solution

Benzonitrile ( C ₆ H ₅ CN ) reacts with a Grignard reagent to form an imine salt, which on hydrolysis gives a ketone. Since the product is benzophenone ( C ₆ H ₅ COC ₆ H ₅ ), the Grignard reagent must provide a phenyl group ( C ₆ H ₅^- ). The formation of hydroxymagnesium bromide ( Mg(OH)Br ) as a by-product indicates that the halogen in the Grignard reagent is bromine. The reaction is: C ₆ H ₅ CN + C ₆ H ₅ MgBr dry ether ( C ₆ H ₅)₂ C=NMgBr ( C ₆ H ₅)₂ C=NMgBr + 2 H ₂ O ( C ₆ H ₅)₂ C=O + NH ₃ + Mg(OH)Br The reagen