Tubular continuous method for preparing cyclopropanecarboxylic acid

Abstract

The invention discloses a tubular continuous method for preparing cyclopropanecarboxylic acid. In the method, gamma-butyrolactone used as a raw material reacts with thionyl chloride and alcohol to produce 4-chlorobutyrate; after the reaction liquid is processed in an acid gas removing way and an alcohol recycling way, the reaction liquid and liquid sodium alkoxide are synthesized to obtain cyclopropanecarboxylate in a tubular reactor; the rectified cyclopropanecarboxylate is firstly hydrolyzed in alkali liquor and then neutralized with acid to obtain crude cyclopropanecarboxylic acid; and the crude cyclopropanecarboxylic acid is rectified to obtain the pure cyclopropanecarboxylic acid. The synthetic technique of the cyclopropanecarboxylic acid adopts the tubular continuous reactor, thereby effectively reducing the equipment investment and enhancing the investment efficiency; the continuous reaction can conveniently realize automatic control, thereby ensuring the continuity and the stability of the production, saving the manual cost, realizing the safe production operation and enhancing the purity and the yield of the product; and the invention adopts a technique of adding solid caustic soda again in the second aqueous phase for recycling, thereby fully and comprehensively utilizing the resources, enhancing the yield for hydrolysis and greatly reducing the cost.

Description

technical field [0001] The invention relates to a method for preparing cyclopropanecarboxylic acid, especially a method for tubular continuous synthesis of cyclopropanecarboxylic acid. Background technique [0002] Cyclopropanecarboxylic acid is an important basic organic raw material widely used in pesticide, pharmaceutical and other industries. The current production methods mainly include the following: [0003] 1. Tetrahydrofuran method. Tetrahydrofuran reacts with HCl to obtain γ-chloro-1-butanol, which is oxidized by concentrated nitric acid to generate γ-chloro-1-butyric acid, and reacts with sec-butanol to generate γ-chlorobutyric acid sec-butyl ester, which is Under basic conditions, dichloromethane is used as a solvent to close the ring under the action of a phase transfer catalyst to generate cyclopropyl ester, which is hydrolyzed and acidified in methanol solution under basic conditions to obtain cyclopropanecarboxylic acid. [0004] 2. Epoxybutene method. Epo...

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Problems solved by technology

[0007] For the production of cyclopropanecarboxylic acid by each of the above processing methods, the whole reaction route of method 1 is too long, and HCl gas is used during the reaction, which causes serious pollution and low yield; The requirements are high and immature; method 3 is a synthetic route that is easy to operate, but the cost of raw materials is high, the yield is not high, and the practical application value is not large; method 4 is a process method with relatively simple process and low raw material cost, and the supply of raw materials is also low. It is very secure and is currently the most mature and promising process route for the production of cyclopropanecarboxylic acid

However, the existing γ-butyrolactone route to produce cyclopropanecarboxylic acid all adopts pressure kettle reactor batch type or tubular reactor semi-continuous synthesis process technology, the equipment investment is relatively large, and it is very difficult to adopt automatic control production, so the product Unstable quality