一种测定3,3′,4,4′-联苯四甲酸二酐纯度的新方法

A New Method for Determination of Purity of 3,3′,4,4′-Biphenyl-tetracarboxylic Dianhydride

试验结果表明在HPLC分析中,3,3′,4,4′-联苯四甲酸二酐(简写作BPDA)难以与其合成中的副产品联苯四甲酸(简写作BPTA)相互分离,而且在流动相通过色谱柱的过程中,由于BPDA与流动相之间产生水解反应又增加了一些BPTA。因此HPLC法测定BPDA纯度误差较大。为此,提出用碱滴定法分析滴定BPDA的醇解及水解产物,根据两者所耗氢氧化钠标准溶液体积之差按文中所给出的公式算得样品中BPDA的含量(即其纯度),与BPDA共存的杂质BPTA对滴定无干扰。在分析纯度为99.58%的BPDA样品时,算得测定值的相对偏差为0.29%。

It was shown that in HPLC analysis, 3,3＇, 4,4＇-biphenyltetracarboxylic dianhydride （BPDA in short） was hardly to be separated from the by-product 3,3＇, 4,4＇-biphenyltetracarboxylic acid （BPTA in short）, and in addition, some more BPTA was produced by hydrolysis of BPDA with the mobile phase when passing through the chromatographic column. Hence, results with significant errors were obtained by determination of purity of BPDA by HPLC. It was proposed that the purity of BPDA can be determined by alkalimetric titration of products of alcoholysis and hydrolysis of BPDA with NaOH standard solution separately, and the content of BPDA （i. e. , its purity） calculated from the difference of volume of the titrant used as shown by the given formula. The presence of the impurity, BPTA, did not interfere with the determination. In the analysis of a sample of BPDA having its purity of 99.58%, the value of relative deviation found was 0. 29%.