Question

a.Identify the two products obtained from the following reaction:

b. A student carried out the preceding reaction, but stopped it before it was half over, whereupon he isolated the major product. He was surprised to find

that the product he isolated was neither of the products obtained when the reaction was allowed to go to completion. What product did he isolate?

Short answer

a.

b. As the${\mathrm{NH}}_2$ group is a better nucleophile than the$\mathrm{OH}$ group, it is the first group that is acetylated.

Step-by-step solution

Step-by-step-solutionStep 1: Reactions of Anhydrides

Carboxylate ion is the leaving group of anhydrides. The reactivity of anhydrides is less than an acid chloride but more than an ester or carboxylic acid. Acid anhydrides combine with alcohols to form an ester and a carboxylic acid.

Identifying the products obtained from the reaction

a. The amino alcohol comprises two groups that is acetylated by acetic anhydride, the${\mathrm{NH}}_2$group and the OH group. In this reaction, two equivalents of acetic anhydride reacts with 3-amino-butan-1-ol. The product obtained in the reaction is 3-acetamidobutyl acetate and two equivalents of acetate ion.

Reaction (a)

b. As the${\mathrm{NH}}_2$ group is a better nucleophile than the$\mathrm{OH}$ group, it is the first group that is acetylated. Hence, if the reaction is stopped before its half over, the product will comprise its ${\mathrm{NH}}_2$group acetylated.