Continuous preparation method of herbicide intermediate 2, 4-dichlorphenoxyacetic acid

Abstract

The invention provides a continuous preparation method of herbicide intermediate 2, 4-dichlorphenoxyacetic acid, which comprises the steps of subjecting 2, 4-dichlorphenoxyacetic acid with a mole ratio of 1: (1.2-1.5) and chloroacetic acid to consecutive reaction through a multistage condensation reaction tower at a temperature of 80-110 DEG C, controlling the PH value of the reaction to be 8-12 through addition of alkali liquor, and finally cooling the liquid material after reaction, subjecting the liquid material to suction filtration and obtaining the 2, 4- dichlorphenoxyacetic acid. Existing interval methods are replaced with the continuous preparation method for preparing the herbicide 2, 4-D acid intermediate 2, 4-dichlorphenoxyacetic acid, the preparation method is easy to operate, the production is safe and can be controlled, the labor intensity of workers is reduced greatly, the production field environment is improved, the safety of the reaction is improved, the discharge of the three wastes is reduced and the production during unit time is increased.

Description

technical field [0001] The invention belongs to the field of preparation methods of herbicide 2,4-D acid intermediates, in particular to a continuous preparation method of herbicide intermediate 2,4-dichlorophenoxyacetic acid sodium. Background technique [0002] 2,4-dichlorophenoxyacetic acid is a representative synthetic plant growth hormone (auxin), referred to as 2,4-D acid. 2,4-D acid shows high activity in common auxin quantification method, but its effect is quite low in oat elongation test using standard auxin quantification method. And it turns purple when treated with chromotropic acid, so it can be used for colorimetric quantification. Since Zimmerman (P.W.Zimmermann, 1942) discovered the role of 2,4-D acid, many synthetic auxins centered on this substance have developed rapidly in agriculture. This substance is used on a large scale as a herbicide and an agent for preventing early fruit abscission. 2,4-D acid can be transferred quite quickly in plants. Accordi...

AI Technical Summary

Problems solved by technology

2,4-D acid showed high activity in common auxin quantification method, but its effect was quite low in oat elongation test using standard auxin quantification method

2,4-D acid can be transferred quite quickly in plants. According to the results of 14C tracing, it is confirmed that this substance undergoes rapid catabolism in the order of carboxyl carbon and then methylene carbon, but its benzene nucleus is not Not easy to disassemble

There are outstanding problems such as poor mass transfer effect, many side reactions, low product yield, poor quality, low production efficiency, high labor intensity, large equipment investment, high manufacturing cost, difficult production management, and poor production stability.