Question

Show the steps for how to isolate 4-aminoacetophenome and benzoic acid from a solid mixture of 4-aminoacetophenome, benzoic acid, and 1,4 - dibromobenzene using acid/base chemistry and recrystallization.

Answer 1

(1) Dissolve the mixture in suitable organic solvent (such as ether)

(2) Add diute NaOH solution, mix well and then separate layers using separatory funnel.

Aqueous layer will contain sodium benzoate and organic layer will contain a mixture of 4-aminoacetophenone and 1,4 - dibromobenzene.

(3) Neutralize the aqueous layer by adding dil HCl. Benzoic acid will precipitate out. Filter the solution. Recrystallize the benzoic acid to obtain pure benzoic acid.

(4) To the organic layer containing 4-aminoacetophenone and 1,4 - dibromobenzene , add dil HCl solution

, mix well and then separate layers using separatory funnel.

Aqueous layer will contain hydrochloride salt of 4-aminoacetophenone and organic layer will contain 1,4 - dibromobenzene.

(5) Neutralize the aqueous layer by adding dil NaOH. 4-aminoacetophenone will precipitate out. Filter the solution.