Method for synthesizing 2-chloro-5-nitrobenzoic acid through microchannel reactor

Abstract

The invention provides a method for synthesizing 2-chloro-5-nitrobenzoic acid through a microchannel reactor. The method comprises the steps of dissolving a raw material o-chlorobenzoic acid into concentrated sulfuric acid to obtain a material 1, and entering a preheating module; adopting fuming nitric acid and the concentrated sulfuric acid as a material 2 and a material 3, and entering another preheating module; preheating the material 1, the material 2 and the material 3, entering a reaction module group for reacting, collecting effluent reaction liquid, processing to obtain a crude product, and refining to obtain the product 2-chloro-5-nitrobenzoic acid. According to the method provided by the invention, the reaction time is shortened to a few minutes to a few seconds, the production energy consumption is reduced, and the reaction efficiency is remarkably improved. High-efficient mass and heat transfer efficiency ensures the reaction temperature to maintain within a setting range, the possibilities of temperature out of control, temperature runaway and even sharp reaction overflow or explosion caused by over-high local concentration do not exist, the intrinsic safety problem of the nitration reaction is solved fundamentally, and the reaction yield and the product purity are remarkably improved.

Description

technical field [0001] The invention relates to the field of organic synthesis, in particular to a method for synthesizing 2-chloro-5-nitrobenzoic acid Background technique [0002] 2-Chloro-5-nitrobenzoic acid is a commonly used chemical intermediate in the field of organic synthesis, mainly used as industrial dyes and pharmaceutical intermediates, the structure is as follows: [0003] [0004] In the field of pharmaceutical synthesis, 2-chloro-5-nitrobenzoic acid is an important intermediate for the synthesis of mesalazine, and in the dye industry, its structure can be used as a commonly used azo dye after modification. Generally speaking, my country's pharmaceutical and dye industries The increasing demand for this kind of chemical intermediates has laid a foundation for the wide application, so its new process development and promotion have broad market prospects. [0005] At present, the production techniques of 2-chloro-5-nitrobenzoic acid mainly include nitration m...

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Problems solved by technology

However, due to the intense heat release of the nitration reaction, the dropwise addition of mixed acid needs to be carried out under low temperature conditions, and the viscosity of concentrated sulfuric acid is extremely high. If there is a slight carelessness during the material mixing reaction process, local concentration, overheating, coking, etc. will occur. In more serious cases, due to the violent oxidation reaction of nitrification and organic matter in the case of excessive local concentration, material flushing or explosion occurs. Therefore, the operation risk of this step of nitrification reaction in large-scale industrial production is extremely high.

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