Method for preparing trifluoro-acetic chloride from tetrachloroethylene

Abstract

The invention relates to a preparation method of a compound, in particular to a method for preparing trifluoro-acetic chloride from tetrachloroethylene. The method comprises the following steps: (1) preparation of dichlorotrifluoroethane: preheating hydrogen fluoride through a hydrogen fluoride preheater to a temperature which is higher than a saturation temperature by 5-80 DEG C, preheating tetrachloroethylene to the temperature being 25-70 through a tetrachloroethylene preheater, then separately feeding the hydrogen fluoride and the tetrachloroethylene into a reactor under the condition thatthe molar ratio of the hydrogen fluoride to the tetrachloroethylene is 6-8: 1, controlling the reaction temperature to be 25-180 DEG C, reacting 10-20 min under the pressure being 0.5-1.5 MPa and under the effect of a catalyst, feeding a material reacted by a reactor into a refluxing tower with the number of theoretical plates being 20-100, and carrying out primary separation to obtain a mixtureof dichlorotrifluoroethane, chlorotetrafluoroethane and hydrogen fluoride on the bottom of the tower, wherein the catalyst is one or more of antimony chloride, zinc chloride, aluminium chloride and bismuth chloride; and (2) preparation of trifluoro-acetic chloride. The preparation method is simple in process, low in cost, high in reaction conversion rate and small in environmental pollution.

Description

technical field [0001] The invention relates to a method for preparing a compound, in particular to a method for preparing trifluoroacetyl chloride from tetrachlorethylene. Background technique [0002] The acid chloride group in TFAC can easily react with amines and alcohols to form amides and esters respectively. It is an important raw material for the synthesis of pesticides and medicines. [0003] Several methods have been disclosed which can be used to prepare TFAC. US3883407 describes the preparation of TFAC by vapor phase oxidation of 1,1,1-trifluoro-2,2-dichloroethane with a water content of less than 0.1% by ultraviolet lamp radiation. This reaction needs to be carried out under certain temperature and pressure. And think that this reaction is not suitable for carrying out in the liquid phase, because the hydrofluoric acid generated by the side reaction will corrode the ultraviolet lamp tube. US5241113 describes the preparation of TFAC by using activated carbon to...

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Problems solved by technology

US5241113 describes the preparation of TFAC by utilizing activated carbon to catalyze the oxidation of 1,1,1-trifluoro-2,2-dichloroethane, the higher reaction temperature causes the carbon-carbon bond in some raw materials to break, and the selectivity is poor

US5041647 describes the preparation of TFAC by oxidizing 1,1,1-trifluoro-2,2-dichloroethane, but water must be used as a catalyst, and the requirement for stirring to prevent local overheating in the reactor is also quite harsh, due to The presence of water to generate TFAC will be accompanied by the generation of trifluoroacetic acid (TFAA), and there are difficulties in the separation of TFAC, TFAA and water

US5259938 describes the preparation of TFAC by liquid-phase oxidation of 1,1,1-trifluoro-2,2-dichloroethane, which improves the selectivity of the reaction by filtering out the part with a wavelength of less than 280nm in the light source, while avoiding glass The corrosion problem of the reactor, the liquid phase material is required to fill the entire reactor during the reaction, and there is no buffer in the gas phase space in the reactor, which is unsafe in industrial production