用于钨酸盐酸碱滴定的各种多元醇作为络合剂的比较研究。

Comparative study of various polyols as complexing agents for the acidimetric titration of tungstate.

作者信息

Verchère J F, Sauvage J P, Rapaumbya G R

机构信息

Unité de Recherche Associée 500 du Centre National de la Recherche Scientifique, Faculté des Sciences de Rouen, Mont-Saint-Aignan, France.

出版信息

Analyst. 1990 May;115(5):637-40. doi: 10.1039/an9901500637.

DOI:10.1039/an9901500637

PMID:2118740

Abstract

Most polyols (L = alditol or carbohydrate) form dinuclear tungstate complexes according to the over-all equilibrium 2WO4(2-) + 2H+ + L equal equilibrium [W2O7L]2- + H2O. When the reaction is fast and complete, it allows the acidimetric titration of tungstate. The formation constants of the complexes of a series of polyols were determined by potentiometry. Their values were higher at low ionic strengths. Opposite structural factors govern the stabilities and the formation rates of complexes: alditols of threo configuration react with tungstate faster than those of erythro configuration, but the stability order is erythro greater than threo. Of the polyols investigated, only xylitol and D-glucitol (sorbitol) allowed a fast and accurate potentiometric titration. Using 0.02 M HCl as titrand, 0.04 mmol of tungstate was determined in a volume of 100 cm3. The interference of molybdate is discussed in detail.

摘要

大多数多元醇（L = 糖醇或碳水化合物）根据总平衡反应2WO4(2-) + 2H+ + L⇌[W2O7L]2- + H2O形成双核钨酸盐配合物。当反应快速且完全时，可用于钨酸盐的酸碱滴定。通过电位滴定法测定了一系列多元醇配合物的形成常数。在低离子强度下其值更高。相反的结构因素决定了配合物的稳定性和形成速率：苏式构型的糖醇与钨酸盐的反应比赤式构型的糖醇快，但稳定性顺序是赤式大于苏式。在所研究的多元醇中，只有木糖醇和D - 葡萄糖醇（山梨醇）能进行快速准确的电位滴定。以0.02 M HCl作为滴定剂，在100 cm3的体积中可测定0.04 mmol的钨酸盐。详细讨论了钼酸盐的干扰。