抄録
The absorption spectra of salicylamine (ο-hydroxybenzylamine) (I), thiosalicylamine (ο-mercaptobenzylamine) (II), and 3-hydroxy-4-aminomethylpyridine (III), have been measured at various concentrations of added acid or alkali in methanol solution. Assignments of the absorption bands to the various molecular species are made. I existed as a nonpolar species, whereas II did as a dipolar species with a dissociated thiol group, in neutral methanol solutions. This was supported by the pKa values (I ; 9.2, 10.5 : II ; 4.7, 9.5) calculated from potentiometric titration curves in aqueous solutions. Both polar and nonpolar species were present in a neutral methanol solution of III. The Al [III], Cd [II], Ni [II] and Zn [II] chelates of II were fairly stable, whereas those of I were not formed appreciably, in methanol. III formed Al [III], Cd [II], Cu [II], Ni [II], and Zn [II] chelates, spectra of which were quite similar to those of metal chelates of pyridoxamine. Spectral change of a solution containing II and Cu [II] ion shows II formed Cu [II] chelate and, then, was converted to benzisothiazol. In the presence of Zn [II] ion, II and sodium pyruvate formed Zn [II] chelate of ketimine Schiff base, which underwent tautomerization to that of aldimine Schiff base very slowly. Possible correlation is noted between pKa's of the phenolic group of pyridoxamine and its analogs and their abilities to form metal chelates and to catalyze the nonenzymatic transamination.
