薬品のポーラログラフ的研究 (第20報)

5-フェニルアゾピリミジン類のポーラログラフィー

抄録

Polarographs and relationship between that and biochemical properties were examined of 2, 4, 6-triamino-5-(R-phenyl) azopyrimidines (A) and 2, 6-diamino-4-hydroxy-5-(R-phenyl) azopyrimidines (B) (in which R is H, Cl, SO₃H, COON, or PO₃H₂). These compounds show reduction wave due to the reaction of -N=N-+2H⁺+2e⇔-NH-NH- and -NH-NH-+2H⁺+2e→-NH₂+NH₂-, its diffusion current constant being ca. 5 (μA⋅mM^-1⋅mg.^-2/3⋅sec.^1/2). The pyrimidine bases and proton adducts of (A) and (B), and 4-phenoxide type anion of (B) indicate different E_1/2. The apparent pK calculated from wave height-pH curve is 4.9-7.2 in (A) and 12 in (B), which are greater than the true pK of 4.38-5.38 in (A) and 9.55 in (B). From these values, proton recombination velocity constant was calculated as log k 3.4-9.7 for (A) and 13 for (B). p-Carboxyphenyl and p-sulfophenyl homologs of (A) indicate prewave due to adsorption and the area occupied by the adsorbed molecule on electrode surface was calculated as 112 Ų from their wave height. The E_1/2 of p-substituted compounds of (A) at pH 1 followed Hammett's rule and is represented as E_1/2=-0.4+0.14σ. The E_1/2 of the antagonist of reduction of folic acid, (A) (R: 4-Cl, 2-Cl, 2, 4-di-Cl) and (B) (R: H) at pH 7.3 is in a more positive potential and those of others (A, R: 4-SO₃H, 4-COON, 4-PO₃H₂, 3-PO₃H₂) are in the negative potential.