1966 年 86 巻 1 号 p. 11-19
It has been found that sulpyrine is produced from a mixture of 4-methylaminoanti-pyrine and sodium hydroxymethanesulfonate even in aqueous solution. On the other hand, a part of sulpyrine is hydrolyzed in aqueous solution into 4-methylaminoantipyrine and sodium hydroxymethanesulfonate as a result of dissociation. Thin-layer chromato-graphic studies revealed that the dissociation product of sulpyrine in aqueous solution is 4-methylaminoantipyrine, and that 4-aminoantipyrine, 4-formylmethylaminoantipyrine, iminobisantipyrine, and 4, 4'-[methylenebis(methylimoino)]diantipyrine are scarcely produced in ordinary condition. As both of the dissociation products were found not to undergo further decomposition or irreversible reaction, quantitative relations among sulpyrine, 4-methylaminoantipyrine, and hydroxymethanesulfonate were investigated by their separatory determination using ion-exchanger resin Dowex 1 x 4 (Cl). Results of these investigations indicate that sulpyrine exists in an equilibrium with 4-methylamino-antipyrine and hydroxymethanesulfonate. Equilibrium constants were measured at some temperatures and different pH solutions, and the effect of pH and temperature on equilibrium constant us discussed. Enthalpy of the dissociation reaction of sulpyrine in aqueous solution was calculated as -7.3 kcal./mole and the equilibrium constant K was related to the absolute temperature T by the formula, log K=1.60.x103/T-2.560.