Preparation method of perfluoronitrile

Abstract

The invention discloses a preparation method of perfluoronitrile. The preparation method comprises the following steps: a, performing a gas-phase addition reaction on perfluoroolefin R1R2C=CR3R4 and carbonyl fluoride to obtain acyl fluoride R1R2(COF)C-CFR3R4 (R1, R2, R3 and R4 have a general formula of a -CnF2n+1 group and n is a nonnegative integer set); b, aminating and dehydrating the acyl fluoride R1R2(COF)C-CFR3R4, acyl fluoride and alkali metal amide or an amine compound R-NH2 (R is lithium, sodium, potassium, rubidium, cesium or a -CmH2m+1 group and m is a nonnegative integer set) to obtain the perfluoronitrile R1R2(CN)C-CFR3R4. By the preparation method, a reaction route is short, the perfluoroolefin and the carbonyl fluoride are easy to obtain and low in price, the overall yield of the perfluoronitrile is high and the route is easy to industrialize.

Description

technical field [0001] The present invention relates to a preparation method of perfluoronitrile, in particular to a method of using perfluoroalkene as a starting material, which first undergoes a gas-phase addition reaction with carbonyl fluoride in the presence of a catalyst to obtain acyl fluoride, and then obtains acyl fluoride under solvent-free conditions. The preparation method of obtaining perfluoronitrile through amination step and dehydration step of fluorine and alkali metal amide or amino compound. Background technique [0002] Up to now, various documents have disclosed four routes for the synthesis of heptafluoroisobutyronitrile. [0003] The first route is the pyrolysis of nitrogen-containing aromatic heterocycles at high temperature or under UV irradiation. The document "Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1981, p.3289–3291" reported that diazine compounds were pyrolyzed under ultraviolet irr...

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Problems solved by technology

[0012] The above-mentioned prior art has the following problems: first, in the first route, the pyrolysis fragmentation reaction of diazine compounds and nitrogen-containing polycyclic compounds is not complete, so the productive rate of heptafluoroisobutyronitrile is low, and three The pyrolysis and fragmentation reaction of azine compounds is very thorough, and the selectivity and yield of heptafluoroisobutyronitrile are very high, but the raw materials are not easy to obtain and the cost is high; the second route has the defect of low yield of heptafluoroisobutyronitrile; The third route has very low yield and selectivity of heptafluoroisobutyronitrile; the reaction route of the fourth route is too long, the intermediate process is too lengthy, and the yield of the first step reaction and the fourth step reaction is low , greatly reduced the total yield of the whole route heptafluoroisobutyronitrile, thereby greatly increasing the production cost of heptafluoroisobutyronitrile,

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