Green Catalytic Activity of Phosphotungstic Acid for Four Hydrogen Sulfide
Four hydrogen sulfide is a chemical intermediate of nitro spray paint, rubber and other solvents, so is often used in the protection of hydroxyl groups.
The catalysts, Lewis acid and ion exchange resin used in the preparation of the four - hydrogen catalyst, all of which have good catalytic effect. However, there are some shortcomings in these methods, such as longer reaction time, reflux, solvent, complex catalyst preparation procedure and unsatisfactory yield.
Phosphotungstates have copper phosphotungstic acid, zinc phosphotungstate and aluminum phosphotungstate. As a kind of heteropoly acid salts, phosphotungstates are widely used as catalysts. It has been proved by experiments that the catalytic activity of phosphotungstic acid for the catalytic hydrogenation of four hydrogen peroxide is better than that of the four hydrogenation of alcohol, thus, a green environmental reaction route is provided for the four hydrogen alkylation reaction better than other methods.
The results show that there are three kinds of phosphotungstates such as copper phosphotungstate, zinc phosphotungstate and aluminum phosphotungstate, which have good catalytic effect on tetrahydropyran. In the reaction catalyzed by copper tungstate, the reaction time of secondary alcohol and tertiary alcohol is longer, and the activity of Bibb alcohol is relatively low; the reaction of aluminium tungstate catalyzed alcohol (except n-butanol, SEC butyl alcohol and tert butyl alcohol) is in progress, the catalytic activity of alcohol is very high, and the structure of alcohol has little effect on the catalytic effect; And zinc phosphotungstate as a catalyst, regardless of which structure of the alcohol structure of its activity are very high.
It can be seen that phosphotungstic acid can provide a simple, new and efficient and environmentally friendly reaction pathway for the protection of hydroxyl groups, which is the effective catalyst for tetrahydropyran.
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