MHTCET 18 Apr 2026 Shift 1 Paper

Concept:Nitriles react with Grignard reagents to form ketones on hydrolysis.Explanation:Benzonitrile is $\mathrm{C_6H_5CN}$.It reacts with a Grignard reagent $\mathrm{RMgX}$ in dry ether.The final product is benzophenone, $\mathrm{(C_6H_5)_2CO}$.So the group added to the nitrile carbon must be a phenyl group, $\mathrm{C_6H_5}$.Hence, the Grignard reagent must contain the phenyl group.Since hydrolysis gives hydroxymagnesium bromide, $\mathrm{Mg(OH)Br}$, the reagent must contain bromine.Therefore, the reagent is $\mathrm{C_6H_5MgBr}$.The reaction is:$$\mathrm{C_6H_5CN + C_6H_5MgBr \xrightarrow[\text{dry ether}]{} (C_6H_5)_2C=NMgBr}$$On hydrolysis:$$\mathrm{(C_6H_5)_2C=NMgBr + 2H_2O \rightarrow (C_6H_5)_2CO + NH_3 + Mg(OH)Br}$$This exactly matches all the given products.Answer:Option D — $\mathrm{C_6H_5MgBr}$