Method for using trichloroethylene to prepare trifluoro-acetic chloride

Abstract

The invention relates to a preparation method of compounds, in particular to a method for using trichloroethylene to prepare trifluoro-acetic chloride. The preparation method includes the following steps: (1) 1, 1, 1 three fluorine 2, 2 preparation of dichloroethane: mixed gas is obtained by the trichloroethylene through fluorination and thermal chlorination; the mixed gas enters a reaction tank filled with activated carbon for catalytic chlorination; the reaction temperature is 180-240 DEG C; the speed ratio of controlling chlorine and the mixed gas in a reaction catalysis process is 1:10-80;after reaction, the gas is washed by water alkali and fractionated to obtain products; (2) preparation of the trifluoro-acetic chloride. The preparation method of the method for using the trichloroethylene to prepare the trifluoro-acetic chloride has the advantages of being simple in process, low in cost, high in reaction conversion rate and little in environmental pollution. The method for usingthe trichloroethylene to prepare the trifluoro-acetic chloride requires gas phase space in a reactor and shading components is arranged below a gas-liquid interface. Mercury lamps are completely submerged under the shading components, thereby being capable of effectively preventing TFAC from being radiated and decomposed by the mercury lamps in the gas phase space and avoiding a corrosion problemof decomposition products to a glass reactor and lamp tubes.

Description

technical field [0001] The invention relates to a preparation method of a compound, in particular to a method for preparing trifluoroacetyl chloride from trichlorethylene. 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