| abstract |
2-Diethylamino-6-chloro-4,8-dipiperidino-pyrimido {5,4d] pyrimidine may be obtained from its mixtures with 2,6-bis- (diethanolamino) -4,8-dipiperidino-pyrimido-5,4-d pyrimidine are separated and recovered, that these mixtures with dilute aqueous solutions of ammonium or alkali hydrogen sulfate at temperatures between 10 and 80 ° C, preferably between 20 and 50 ° C, stirred and the remaining undissolved 2-Diäthanolaminc-δ-chloro-4, 8-dipiperidino-pyrimido [5,4-d] pyrimidine separates. |