新试剂2-(2-苯并噻唑偶氮)-5-氨基苯甲酸与铂(Ⅳ)的显色反应研究

STUDY ON THE SYNTHESIS OF 2-(2-BENZOTHIAZOLYLAZO)-5-AMINOBENZOIC ACID AND ITS COLOR REACTION WITH PLATINUM(Ⅳ)

合成了新试剂2-(2-苯并噻唑偶氮)-5-氨基苯甲酸(BTABA),研究了新试剂与铂(Ⅳ)的显色反应,先后在pH 4左右的乙酸盐缓冲及H2SO4和H3PO4混合介质中,在表面活性剂CTMAB存在下,形成了配位比为Pt(Ⅳ):BTABA=1:2的红褐色配合物,其最大吸收波长为612 nm,表观摩尔吸光系数为1.12×105L·mol-1·cm-1.铂含量在0～30.0μg/25 mL范围内服从比耳定律.应用于Pt-C催化剂中铂的测定,结果满意.

2-（2-Benzothiazolylazo）-5-arninobenzoic acid （abbreviated as BTABA）, as a new color reagent, was synthesized and its molecular structure characterized by elementary analysis and IR spectrometry. In an acetate buffer of around pH 4, and in the presence of CTMAB, a henna colored coordination complex is formed between BTABA and Pt（Ⅳ） （R： Pt=2 ： 1）, upon heating the reaction solution for 5 min in boiling water bath. The sensitivity of the color reaction is evidently raised upon the addition of an appropriate amount of sulfuric acid and phosphoric acid making the acidity of the reaction solution raised to about 0. 25 mol · L^-1 in sulfuric acid. Ethyl alcohol is added to the solution to a content of above 50% by volume. The absorption maxima of the coordination complex was found at the wavelength of 612 nm, with its molar absorptivity （ε） of 1.12×10^5L·mol^-1·cm^-1. Beer＇s was found to hold in the range 0-30μg of Pt（Ⅳ） per 25 mL of solution. In the application of this method to the determination of platinum in a sample of Pt-C catalyst, average RSD （n = 6） was found to be 1.06% at a concentration level of 10 μg of Pt （IV）, and average recovery （n = 5） found by standard addition method was 104. 4%.