Answer to Question #89841 in Organic Chemistry for SK Abidur Rahaman

Question

compare reactivity of alkyl chloride and acyl chloride?

Answer 1

The following is general structures of acyl and alkyl chlorides:

In comparison with alkyl chlorides, acyl chlorides have a group -COCl with two electonegative atoms (O and Cl) attached to carbon. This leads to much more polarized C-Cl bond in acyl chlorides compared to alkyl chlorides, thus acyl chlorides are much more reactive in nucleophilic substitution reactions.

Moreover substitution of a chlorine in an acyl chlorides with nucleophile happens as a tandem of addition and elimination reactions:

Two stage process occurring with acyl chlorides has a lower activation energy than one step S_N2 process that happens in the reaction of a primary alkyl chlorides with nucleophiles. A lower activation energy leads to a faster reaction for acyl chlorides.