Abstract: 2,6-Dichloropurine was obtained by chloration of 2,6-dithiopurine, which is a thiolated (cyclocondensing) product of 4,5-diamino-6-hydroxy-2-mercaptopyrimidine with formamide. The reaction (conditions) of thiolation and chlortion(e.g.using hydrochloric acid instead of acetic acid and direct chloration in concentrated hydrochloric acid) were improved and put to industrial production.