Stability of Sulpyrine. I. Reversible Hydrolysis in Alkaline Solution

抄録

Hydrolysis of sulpyrine was investigated in neutral and alkaline solution. 4-Methylaminoantipyrine (MAA), 4, 4'-[methylenebis (methylimino)] diantipyrine (Bis), and 4-(N-hydroxymethyl-N-methyl) aminoantipyrine (HMA) were identified as hydrolyzed products by nuclear magnetic resonance spectroscopy and spectrophotometry, and the determination methods of them were proposed. Sulpyrine was in an equilibrium with these products and the percent composition of each species at equilibrium was affected by the initial concentration of sulpyrine. The ratios of the equilibrated amounts of Bis and HMA to that of MAA increased with an increase in the initial concentration of sulpyrine. The apparent rate constants of hydrolysis and formation of sulpyrine were determined in the moderately diluted solution (below 4.5 mg/ml) where Bis was negligible. The results suggest that the apparent rate of hydrolysis is independent of pH, whereas that of formation apparently decreases with an increase in pH values, which is ascribed to an increase in the dissociation of hydroxymethanesulfonate into formaldehyde and bisulfite.