4,4'-Disulfanediylbis(6-methylpyrimidin-2-amine)

4,4'-BIS(2-AMINO-6-METHYLPYRIMIDYL) DISULFIDE is readily prepared from commercially available 2-amino-4-chloro-6- methylpyrimidine, which is treated with NaS.H2O (5 equiv) in degassed propylene glycol at 140 °C for 3 h. The solution is diluted with H2O and neutralized with acetic acid. The collected precipitate is recrystallized from ethanol, giving pure 2-amino-4-mercapto-6-methylpyrimidine, which is dimerized with iodine in boiling methanol containing potassium carbonate.