8.02 g (38 mmol) of sodium 2-ethylsulfanilate are added at 100° C. to a melt of 9.48 g (40 mmol) of 2-ethoxyoxalic acid anilidemonoethyl ester and 5.44 of imidazole. The reaction mixture is heated for 1/2 hour to 110° C., then for 2 hours to 130° C. After cooling, the...