Nucleophilic Substitution at Centers Other than Carbon: Reaction at the Chlorine of N-Chloroacetanilides with Triethylamine as the Nucleophile

Article abstract of DOI:10.1021/jo00200a042

The reaction between triethylamine (TEA) and a series of para-substituted N-chloroacetanilides has been studied in aqueous solution buffered to pHs between 1 and 5.In these reactions, the exclusive product derived from the aromatic moiety is the corresponding acetanilide.The reaction occurs via two parallel pseudo-second-order paths, one acid catalyzed (the Orton-like mechanism), the other uncatalyzed.The uncatalyzed reaction is accelerated by the presence of electron-withdrawing substituents on the aromatic ring and can best be represented as nucleophilic displacement at chlorine.It therefore appears to be the prototype of a convenient class of reactions for the study of displacement reactions at chlorine.The ρ value for this reaction is 3.87 indicating substantial negative charge buildup in the aromatic ring during the transition state.The acid-catalyzed reaction is more complex, presumably involving a protonation equilibrium for the N-chloroacetanilide prior to the rate-determining step similar to that in the Orton reaction.