Formation and hydrolysis of enamine in aqueous solution.
作者:TOSHIAKI NISHIHATA、JUNKO KATO、KIHEUN KIM、MOTOMASA KOBAYASHI、ISAO KITAGAWA、AKIRA KAMADA
DOI:10.1248/cpb.32.4545
日期:——
A mixture of sodium phenylalanine and ethyl acetoacetate in aqueous solution underwent enamine formation as determined by nuclear magnetic resonance- and ultraviolet-spectroscopic measurements. An equilibrium state was observed in the aqueous solution between the enamine and the starting materials. Although the observed equilibrium constant, Kobs, showed dependency on the pH value of the solution, the equilibrium constant, K, was not influenced by the pH value. The effect of pH values on Kobs was related to the pKa value of phenylalanine, suggesting that only the unionized form of the amino moiety of phenylalanine could take part in the enamine formation.
通过核磁共振和紫外光谱测量,确定了水溶液中苯丙氨酸钠和乙酰乙酸乙酯的混合物会形成烯胺。在水溶液中观察到烯胺和起始材料之间的平衡状态。虽然观察到的平衡常数 Kobs 与溶液的 pH 值有关,但平衡常数 K 却不受 pH 值的影响。pH 值对 Kobs 的影响与苯丙氨酸的 pKa 值有关,这表明只有苯丙氨酸氨基的结合形式才能参与烯胺的形成。