Pure Aspartates for High Performance Coating Systems

Abstract

The use of N-substituted aspartates as intermediates to prepare paints requires that these substances contain only minimum fumarates which often accompany them as undesirable impurities. To develop a method of removing fumarates from aspartate mixtures, a model was chosen, namely, the product of the reaction of cyclohexylamine and diethyl maleate. Here, diethyl N-cyclohexyl aspartate is the main product and, simultaneously with this aza-Michael addition, diethyl fumarate is formed by isomerization of diethyl maleate. Methods were proposed and verified to remove the formed fumarate and excess primary amine from the reaction mixture.