Crystallization and purification method of hydroxyalkyl amide

Abstract

The invention relates to a crystallization and purification method of hydroxyalkyl amide. The hydroxyalkyl amide is prepared through reactions between dialkanol amine and dialkyl dicarboxylate in the presence of an alkaline catalyst and then the reaction product is crystallized and purified. The crystallization and purification method comprises the following steps: (a) adding a certain amount of crystallizing solvent into the reaction products; (b) stirring to dissolve the reaction products, carrying out reflux, and cooling the temperature to 90 DEG C or less; (c) cooling the solution to a temperature of 20 to 30 DEG C in a water bath so as to primarily precipitate the crystals; (d) filling liquid nitrogen to further cool the solution to a temperature of -25 to -5 DEG C so as to fully precipitate the crystals; (e) filtering, and drying to obtain the crystallized and purified hydroxyalkyl amide product; (f) recovering the mother liquor after filtering and using the mother liquor as the crystallizing agent again. The provided method can fully precipitate the hydroxyalkyl amide; the mother liquor after crystallization can be repeatedly used for several times, the quality degradation is effectively avoided, and the yield and product quality are prominently improved.

Description

technical field [0001] The invention belongs to the technical field of purification of reaction products, and relates to a method for crystallization and purification of reaction products, in particular to a method for crystallization and purification of reaction products of dialkanolamine and dialkyl carboxylic acid in the presence of a basic catalyst. Background technique [0002] Hydroxyalkyl amides are obtained by the amidation reaction of dialkanolamines with dialkyl carboxylic acids under base catalysis. Among them, the reaction product generally contains residual dialkanolamine, residual basic catalyst and other by-products. At the same time, the crystallization of the reaction product is generally based on the method of cooling crystallization with cold water, and the crystallization rate is not high. The solvent recovered after crystallization participates in When the next batch is recycled, the residual product in the solvent will undergo changes such as yellowing,...

AI Technical Summary

Problems solved by technology

Among them, the reaction product generally contains residual dialkanolamine, residual basic catalyst and other by-products. At the same time, the crystallization of the reaction product is generally based on the method of cooling crystallization with cold water, and the crystallization rate is not high. The solvent recovered after crystallization participates in When the next batch is recycled, the residual product in the solvent will undergo changes such as yellowing, which will affect the quality of subsequent products, resulting in low overall product yield and poor product quality