18.7 parts of 1-phenyl-4-aminopyridazone-(6) and 19 parts of dimethyl
sulfate in 400 parts of xylene are kept at 120°C for one hour while mixing
well. The reaction mixture is suction filtered, 28 parts (89.5% of the theory)
of 1-phenyl-4-amino-6-methoxypyridazinium methosulfate is obtained having
a melting point of 173°C to 174°C after recrystallization from acetonitrile. The
perchlorate has a melting point of 179°C to 182°C.
