Vergleich der Dissoziationskonstanten von 2-Amino-thiazol- und 2-Amino-oxazol-Derivaten

Abstract

A description is given for the synthesis by standard methods of 2-Amino-4-phenyl- and 2-Amino-5-phenyl-thiazoles having different para-substituents together with the 2-Amino-4-phenyl-oxazole analogues. The pK_a-values were determined for the compounds in alcohol-water-(1:1) at 25°. Of the three classes, the oxazole-derivatives are the least basic and the 5-substitued thiazoles are the most basic. The pK_a-values for all members of the three classes are linearily correlated with the σ_para-values of the substituents in the phenyl-ring.