See image — Reaction Mechanism Chemistry Question

💡 Solution & Explanation

Step 1: Identify the first reaction. H2C=CHCH2Br (allyl bromide) reacts with NaCN (sodium cyanide) in an SN2 reaction. The cyanide ion (CN-) acts as a nucleophile and displaces the bromide, giving Y = H2C=CHCH2CN (allyl cyanide / but-3-enenitrile). Step 2: Identify the second reaction. Y (H2C=CHCH2CN) is treated with C6H5MgBr (phenylmagnesium bromide, a Grignard reagent) in diethyl ether, followed by aqueous acid workup (H3O+). Step 3: Grignard reagent reacting with a nitrile. When a Grignard reagent reacts with a nitrile (R-CN), the Grignard adds once to the carbon-nitrogen triple bond to form an imine salt (metalated imine). Upon aqueous acid hydrolysis (H3O+), the imine intermediate (RCO-NH2 after tautomerism/hydrolysis) actually first gives an imine which hydrolyzes to a ketone. Specifically: R-CN + R'MgBr -> R-C(=NMgBr)-R' --H3O+--> R-C(=O)-R' + NH3 (or NH4+) So Y = H2C=CHCH2CN reacts with C6H5MgBr then H3O+ to give: H2C=CHCH2C(=O)C6H5 (an aryl ketone, allyl phenyl ketone / 1-phenylbut-3-en-1-one) This matches option (a): H2C=CHCH2C(=O)C6H5. Why other options fail: - Option (b): An amide product would not form under these Grignard conditions with a nitrile. - Option (c): An alcohol with -CH(OH)C6H5 would result from Grignard addition to an aldehyde, not a nitrile. - Option (d): An amine product (-CH(NH2)C6H5) would require reductive amination or a different reaction pathway, not simple Grignard + nitrile. Therefore, the correct answer is A.