间氯偶氮安替比林的纯化鉴定及其离解常数和质子化常数的测定

Purification and Identification of meta-Chloroantipyrylazo and the Determination of Dissociation Constant and Protonation Constant

本文研究提出了适合于新显色剂间氯偶氮安替比林的纯化新方法,经该方法纯化后的试剂在纸色谱图上仅有一个斑点,元素分析结果也令人满意。经过元素分析、热重分析和红外吸收光谱的测定,进一步确定了试剂的组成和结构。首次用光度法测定了试剂的离解常数(pKa=7.35±0.03)和质子化常数(1ogKp=-3.50±0.17)。

The method for purification of m-chloroantipyrylazo by rccrystallization and extraction was established. The purification and the purity of m-chloroantipyrylazo were controlled or checked by paper chromatography. For the pure product, a single purple band was obtained. The composition and structure of m-chloroantipyrylazo were also determined by elemental analysis, TG and IR analysis. Then, the value of dissociation constant, pKa=7. 35±0. 03, and the protonation constant, logKp=-3. 50±0. 17, were determined by spectrophotometric method.