Question

Account for the following:

CH₃CHO is more reactive than CH₃COCH₃ towards reaction with HCN.

Answer 1

CH₃COCH₃ is sterically hindered than CH₃CHO due to the presence of alkyl group on both sides of the carbonyl carbon, making them less reactive towards nucleophilic attack because both methyl groups have electron releasing tendency due to -I effect. These alkyl groups make ketone less reactive by donating electron to carbonyl group.Therefore, acetaldehyde is more reactive towards reaction with HCN.