Kevlar®, a polymeric aromatic amide, is synthesized from the monomers p-phenylenediamine (left) and terephthaloyl chloride (right). The polymer strands are initially aligned randomly, but they are dissolved and spun to give a lightweight, flexible product that is five times stronger than steel of the same weight

The first step in the reaction of an amine with an acid chloride is

(a) Describe this step in terms of a Lewis acid-base reaction.

(b) Would you expect water or ammonia to react faster with an acid chloride? Explain

(a)

It is stated that the reaction is a Lewis acid-base reaction since they produce an adduct In the adduct, the nitrogen of the ammonium functional in this reaction is attached to the carbon of the acid chloride functional group. The nitrogen in this case has a lone pair of electrons which makes it electron rich. Nitrogen donates its lone electron to the carbon which makes nitrogen (donated electrons) the Lewis base and carbon (accepted electrons) the Lewis acid.

Hence the steps in this reaction is described in the explanation

(b)

Ammonia is a better or stronger base than water so it will improve the acidic character of the acid chloride. Ammonia will more easily donate its electron than water so the reaction will more likely proceed or will happen faster.

Hence, I expect ammonia to react faster with an acid chloride.