When aminolysis of N⁴-[5'-(3'-methylmercapto-6'-methyl)-1', 2',4'-triazinyl]-3-methylmercapto-5-oxo-6-methyl-4,5-dihydro-1,2,4-triazine (Ⅱ) with a series of aliphatic and aromatic amines was conducted in hot ethanol, 5-substituted amino-3-methylmercapto-6-methyl-1,2,4triazines (Ⅲ_a-b) and 3-methylmercapto-5-hydroxy-6-methyl-1,2,4-triazine (Ⅰ) were obtained (Table 1).No reaction took place with p-nitroaniline, o-chloroaniline, or with o-toluidine.When compound (Ⅱ) reacted with isobutylamine or with ammonia in hot ethanol, 3-isobutylamino-5-hydroxy-6-methyl-1,2,4-triazine (Ⅳ_a) or 3-amino-5-hydroxy-6-methyl-1,2,4triazine (Ⅳ_b) was obtained respectively in addition to the 5-substituted amino-3-methyhnercapto6-methyl-1,2,4-triazine (Ⅲ_d,e) and 3-methylmercapto-5-hydroxy-6-methyl-1,2,4-triazine (Ⅰ).