Method for preparing perfluoronitrile by gas phase catalysis

Abstract

The invention discloses a method for preparing perfluorinated nitrile through gas phase catalysis. The method comprises the following steps: a, in the absence of a catalyst, enabling acyl fluoride R1COF or perfluor substituted ethylene oxide Cyclo-CF2-CR2R3-O- to perform a gas phase amination reaction with an ammonia gas or a primary amine compound, to obtain amide of which a general formula is R1CONH2 or CR2R3FCONH2, wherein general formulas of R1, R2 and R3 are CnF[2n+1], CxF[2x+1], and CyF[2y+1], wherein x and y are non-negative integer sets, x+y=n, and n is a positive integer set; and b, in the presence of the catalyst, dehydrating the amide R1CONH2, to obtain the perfluorinated nitrile R1CN. The method is short in reaction route, and the perfluor substituted ethylene oxide or the acylfluoride is easily obtained. A total yield of the perfluorinated nitrile is high, and the route is easy for continuous industrialization.

Description

technical field [0001] The present invention relates to a method for gas-phase catalytic preparation of perfluoronitrile, in particular to a gas-phase reaction with ammonia or primary amine compounds using acyl fluoride or perfluoroethylene oxide as a starting material in the absence of a catalyst. Amination reaction to obtain perfluoroamide, followed by gas-phase dehydration reaction in the presence of a catalyst to obtain perfluoronitrile. Background technique [0002] Up to now, various documents have disclosed seven routes for the synthesis of pentafluoropropionitrile. [0003] The first route is the free radical reaction method. The document "J.Chem.Soc., Furuduy Trans.I, 1982, 18, 3493-3498" reported that under the illumination of a high-pressure mercury lamp, pentafluoroiodoethane reacted with cyanogen chloride free radicals, and at 300 degrees, When the photolysis time is 1.98 seconds, the conversion rate is only 17.3%, and the reaction equation is shown in (1). ...

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Problems solved by technology

[0018] The above-mentioned prior art has the following problems: firstly, the first route has the disadvantages of unavailable raw materials, low conversion efficiency, and no industrial value; the second route has simple reactions and high conversion rates, but raw materials are difficult to obtain, and the process is intermittent The organic raw materials of the third route are not easy to obtain, and there are many reaction by-products; the sodium azide used in the fourth route is a high-risk substance that is easy to explode under high heat or collision, and it is difficult to safely Operation; the fifth, sixth, and seventh routes all have the defects that the raw materials are difficult to obtain and the reaction yield of the target product is low

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