PROCESS FOR THE PREPARATION OF CIMETIDINE

摘要

Process for the preparation of cimetidine, wherein N-cyano-N'-methyl-N"-(2-mercaptoethyl)guanidine is reacted with 4-halomethyl-5-methyl-lH-imidazole in water or in a water-containing medium at the pH-range of 8.0 to 9.5. Pure cimetidine crystallizes from the reaction mixture immediately without any particular operations with a yield higher than 70 %.