黄、白钨酸制备法的差异,以及粉状白钨酸反应研究的进展

本文扼要总结了作者多年来对钨酸制备方法的研究。与传统方法不同,黄钨酸得自浓盐酸的均相沉淀法。粉状白钨酸是一个活性化合物,乃将Na₂WO₄滴入1 M HNO₃至pH值近于1时制得。此类白钨酸可作为制备偏钨酸、杂多钨酸,包括有机砷多钨酸盐的原始材料。

DISCREPANCY BETWEEN METHODS OF PREPARING YELLOW AND WHITE TUNGSTIC OXIDE HYDRATES,AND VERSATILE USES OF THE LATTER

A brief review is given for the mechanism in preparing yellow tungstic oxide hydrate through homogeneous precipitation from concentrated hydrochloric acid solution,as represented by scheme 2 given in this paper. It is in contrast to the conventional method of acidification. White powdery tungstic oxide. hydrate, an active species, is prepared according to scheme4, i.e., by dropping Na₂WO₄ solution with stirring into 1M HNO₃ until pH reaches around 1,—a reversed way of acidification. The micro-crystalline white tungstic oxide hydrate thus obtained is highly active,as represented in scheme 3. Besides preparing low valent tungsten clusters, superfine WC,light sensitive WO₃·_xH₃O, and WO₃ aggregate pyridine compounds, that white tungsten oxide hydrate can also lead to the preparation of a host of metatungstates, heteropolytungstates including organoarsenic polytungstates, as revealed in scheme 3 of the above text.