Diethyl aminomalonate hydrochloride is used as a pharmaceutical intermediate. Diethyl aminomalonate with formaldehyde generates an azomethine ylide which can undergo cycloadditions with 1,2-dipolarophiles to form pyrrolidines.
A solution of 420.0 g of a mixture of diethyl hydroxyiminomalonate and diethyl acetoxyiminomalonate (together 2.0 mol) in 400 ml of ethyl acetate, 40.0 g of anhydrous magnesium sulfate and 12.5 g of palladium on activated charcoal (5 percent by weight of Pd) as hydrogenation catalyst were placed in a 1.5 l pressure reactor equipped with a stirrer. At 30° to 35° C., hydrogen was introduced under a pressure of 20 bar for 80 minutes until the pressure remained constant. The reactor contents were thoroughly mixed by stirring during this process. The hydrogenation mixture was cooled to 20° C. and diluted with 200 ml of ethyl acetate and the mixture of hydrous magnesium sulfate and catalyst was filtered off. The solid which had been separated off was washed three times with a total of 200 ml of ethyl acetate and the wash liquor was combined with the filtrate. Diethyl aminomalonate hydrochloride was precipitated out as a white solid by the introduction of 68 g of dry hydrogen chloride, filtered off, washed with ethyl acetate and dried under a water jet vacuum at 70° C. The yield was 359.6 g (85.1% of theory), the melting point was 165° C. and the purity according to the analytically determined chlorine content was 100%.
