PURPOSE: To obtain the compd. in an extremely pure form at a high yield by bringing diaminotoluene into reaction with diethylcarbonate in the presence of a catalyst and removing the formed alcohol by distillation.
CONSTITUTION: The diaminotoluene is brought into reaction with the diethylcarbonate in molar excess of at least 5 times, more particularly 10 to 30 times the stoichiometric amt. on the basis of the amino group of the diaminotoluene at 100 to 300°C, preferably 120 to 250°C, in the presence of the catalyst, preferably a compound of tin, fine and lead and the formed alcohol is removed by the distillation. The product of the stage described above is cooled until the crystal of bis-(ethoxycarbonyl-amino)-toluene is formed. The formed crystalline objective compd. is then obtd. The formation of a large amt. of by-products, more particularly early crystallized polyurea, is prevented by the use of the excess amt. of the diethylcarbonate. The diisocyanate toluene is obtd. by pyrolyzing the resulted bis-(ethoxycarbonyl-amino)-toluene.
TOMASU SHIIBE
SUTEFUAN BUERUSHIYOTSUFUEN
