Synthesis of Acetanilide and Purification by Recrystallization
Par, B., Ramos, S., Reynaldo, H., Roque, P., Servidad, Y., and Soriente, P.
2D-Pharmacy, Group No. 7, Department of Pharmacy, Faculty of Pharmacy, University of Santo Tomas, España Boulevard, 1015 Manila, Philippines

Abstract Recrystallization is the primary method of purification used to isolate organic compounds in a supersaturated solution by the difference of solubility at different temperature that results to the separation of the compound from the solution. The purpose of this experiment is to synthesize acetanilide by the acetylation of aniline and to obtain pure acetanilide by purification of the collected crude acetanilide by crystallization. The recrystallizing solvent was chosen among ethanol, water and hexane. The acetanilide was synthesized and formed by acetylation of aniline and acetic anhydride, and it was then cooled to hasten the formation of crystals. After cooling, the mixture was filtered and dried to obtain the crude acetanilide. The crude acetanilide and the chosen recrystallizing solvent was mixed and heated in the water bath until the solid dissolved. The solution was filtered while hot and its filtrate was cooled in an ice bath. The filtrate was then filtered to collect the crystal residue formed. The crystals were washed with distilled water and allowed to dry to obtain the pure acetanilide. The weight of pure acetanilide was measured and the melting point of the pure acetanilide was determined. Based on the results obtained, water is the best recrystallizing solvent among the three given solvents and the limiting reagent in synthesis of acetanilide is aniline.

Introduction

Purification of a solid by recrystallization from a solvent depends on the fact that different substances are soluble to different solvents. The impurities are much more