Preparation method of 2, 4-dichlorobenzotrifluoride

Abstract

The invention discloses a preparation method of 2, 4-dichlorobenzotrifluoride, which comprises the following steps: (1) nuclear chlorination: taking parachlorotoluene as a raw material, carrying out multiple times of rectification and separation on the raw material nuclear chlorination in a rectification tube type integrated reactor under the action of a Lewis acid catalyst, and carrying out rectification and separation on the product to obtain a mixture of 2, 4-dichlorotoluene and 3, 4-dichlorotoluene; and (2) side chain chlorination: carrying out side chain chlorination on the mixture of the 2, 4-dichlorotoluene and the 3, 4-dichlorotoluene under the action of a photochlorination catalyst and an inhibitor to obtain a mixture of the 2, 4-dichlorotrichlorotoluene and the 3, 4-dichlorotrichlorotoluene. And (3) fluorination: reacting the side chain chlorination product with hydrogen fluoride under the action of a fluorination catalyst, after directional side chain fluorination, removing acid and moisture in the reaction liquid, and rectifying and separating to obtain the product 2, 4-dichlorobenzotrifluoride.

Description

technical field [0001] The invention relates to the field of chemical industry, in particular to a preparation method of 2,4-dichlorobenzotrifluoride. Background technique [0002] 2,4-Dichlorotrifluorotoluene is an intermediate of the herbicide dichloramine, and it can also be used in the fields of medicine, dyes and polymers. It is an important organic intermediate and has a good market application prospect. At present, there are few studies on its synthesis, mainly concentrated in a few domestic companies, and there are no relevant reports on its industrialization. This is mainly due to the fact that in the synthesis process, side reactions easily occur, the products are diversified and have no obvious practical value, and the recovery of catalysts is difficult, etc., which restricts the process of its industrialization. [0003] There are two main preparation techniques for 2,4-dichlorobenzotrifluoride: one is prepared from 2,4-dichlorotoluene through side chain chlorin...

AI Technical Summary

Problems solved by technology

Australian patent AU2016102216A4 discloses a process for preparing 2,4-dichlorotoluene by reacting 2,4-diaminotoluene as a raw material with a solution of potassium chloride and cobalt chloride, with a yield of 85%. The process starts with The raw materials are expensive, and there are many waste water and waste salts, which are not suitable for large-scale production; Chinese patent CN1080279A discloses a kind of 3-chloro-4-methylaniline as raw material, which is diazotized and Sandmeyer reaction 2,4-dichlorotoluene is prepared with a yield of 88%. The starting materials of this process are also expensive, and the requirements for process safety and environmental protection are relatively high

Therefore, from the point of view of economy, safety and environmental protection, taking p-chlorotoluene as raw material to synthesize 2,4-dichlorobenzotrifluoride is the route most suitable for industrialization at present, but the prior art has low yield, many by-products, chlorine Disadvantages such as difficult depth control

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