The preparation of powdery white tungstate acid The color of tungstate is yellow and white, and there is the difference between powdery and gelatinous. The yellow glue is a mixture of yellow powder and white gelatinous and the white powdery tungsten acid, which is more or less mixed with gelatinous material, is not easy to make up. So long time, yellow powdery tungstate only as the representative of tungstic acid, and as the basic raw material for the preparation of metal tungsten and other tungsten compounds。
The differences in preparation of yellow and white tungsten-acid and the progress of the study on the reaction of powdery tungsten-acid. This paper summarizes the author's research on the preparation of tungstic acid. In contrast to the traditional methods, yellow tungsten acid has been precipitated by the homogenized hydrochloric acid. Powdery white tungstic acid is an active compound, which is obtained by dropping NaZwO from 1MHNO3 to a pH of 1. This type of white tungstic acid can be used as the raw material for the preparation of tungstenic acid and heteropoly tungstate, including organic arsenic polytungstate。
The catalytic oxidation of cyclohexene by tungsten-catalyzed cyclohexene is &; With tungsten acid/organic acid additive as catalytic system, in the absence of organic solvent, under the condition of phase transfer agent, 30% hydrogen peroxide oxidation of cyclohexene catalyzed synthesis of adipic acid. When tungstate, organic acid additives, cyclohexene, hydrogen peroxide = 1:1:40:176 (mole ratio, dosage of tungstate 2.5 tendency), using organic acid additive review the catalytic properties of tungsten acid, the results show that tungsten acid/benzodiazepines between catalytic oxidation of cyclohexene optimal catalytic effect, reaction 8 h adipic acid separation yield and purity of 90.9% ~ 90.9%; Without using organic acid additives, separation of adipic acid production rate is only 72.1%, product purity of 96.2%, when using sulfonic acid, salicylic acid, oxalic acid, salicylic acid as the organic acid additives, with the increase of reaction time, the separation of adipic acid production rate are higher, but the reaction after 6 h, separation of adipic acid production rate does not change significantly with time. When the dosage of sulfonic acid is 2.5 tendency, adipic acid separation yield and purity were higher. Tungsten acid - sulfonic acid, salicylic acid catalytic system reuse after five times, adipic acid separation production rate can reach 80.5%.
Study of powdery white tungstate acid. This report USES the ion exchange performance of powdery white tungstate to directly prepare a series of monovalent cationic salts. The powdery white tungstate acid obtained at normal temperature and low acidity with a droplet addition has a large chemical activity, which can dissolve (with weak gelation) in water, forming a tenotungstic acid.