Method for preparing trifluoroacetyl chloride

Abstract

The invention discloses a method for preparing trifluoroacetyl chloride (TFAC), comprising the following steps: 1) HCFC-123 is added into a reactor, oxygen and chlorine are continuously introduced while stirring, photochemical oxidation reaction is carried out through mercury lamp radiation, the reactant is continuously exhausted from the upper part of the reactor in the form of gas phase, and the liquid level in the reactor keeps constant by continuously supplementing HCFC-123; and 2) the vaporized HCFC-123 in the reaction is condensed by a condenser installed above the reactor and flows back into the reactor to continue participating in the reaction, the product TFAC is exhausted from the top of the condenser and is collected after compression and condensation, the by-product hydrogen chloride is absorbed by water washing and the unreacted chlorine is processed by alkali washing absorption. In the method, the reactor is required to have gas phase space, a shading component is arranged below the gas-liquid phase interface and the mercury lamp is totally immersed below the shading component, thus effectively preventing the generated TFAC from radiolytic decomposition by the mercury lamp in the gas phase space and avoiding the decomposition products from corroding the glass reactor and the lamp tube.

Description

technical field [0001] The invention relates to a preparation method of a compound, in particular to a preparation method of trifluoroacetyl chloride. 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, has described and is less than 0.1% HCFC-123 preparation TFAC by ultraviolet lamp radiation vapor phase oxidation, this reaction needs just can carry out under certain temperature and pressure, and thinks that this reaction is not suitable for carrying out in liquid phase, because The hydrofluoric acid produced by the side reaction will corrode the UV lamp. US5241113 describes the preparation of TFAC by using activated carbon to catalyze the oxidation of HCFC-123. The higher reaction temperature causes the carbon-car...

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Problems solved by technology

US5241113 describes the preparation of TFAC by utilizing activated carbon to catalyze the oxidation of HCFC-123, the higher reaction temperature causes the carbon-carbon bond in some raw materials to break, and the selectivity is poor

US5041647, has described to prepare TFAC by oxidizing HCFC-123, but must use water as catalyzer, also quite harsh to the requirement of stirring in order to prevent local overheating in the reactor, can be accompanied by trifluoroacetic acid (TFAA) when the existence of water generates TFAC ), the separation between TFAC, TFAA and water is also difficult

US5259938 describes the preparation of TFAC by liquid-phase oxidation of HCFC-123, which improves the selectivity of the reaction by filtering out the part with a wavelength of less than 280nm in the light source, and at the same time avoids the corrosion problem of the glass reactor. During the reaction, the liquid-phase material is required to fill the entire Reactor, there is no buffer in the gas phase space in the reactor, which is unsafe in industrial production

US5296640 describes the preparation of TFAC by oxidizing HCFC-123 in a supercritical state. In the reaction, by-products hydrofluoric acid and TFAA are produced. In addition, the high temperature and pressure in the supercritical state are demanding on the reactor, which is difficult to realize industrially.

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