Dr. Sereda, in an acylation of amines, is it essentially a substitution reaction and the amine acts as a nucleophile? (Yes, it is an acyl substitution. The mechanism is similar to that shown in U.CAN for Fischer esterification. - GS). For instance, if an acyl group attached to a halide reacts with an amine group, des the halide act as a leaving group on the acyl group, and the amine attacks as a nucleophile (Yes. You are correct. - GS).