Method for synthesizing phenoxy carboxylate herbicide original medicine

Abstract

The invention discloses a method for synthesizing a phenoxy carboxylate herbicide original medicine. The method comprises the following steps of: adding chlorophenol and alkaline liquid to a reactor, reacting to produce soluble chlorophenate, and drying liquid through evaporating, so as to obtain solid soluble chlorophenate; adding chlorinated carboxylate liquid into the reactor, reacting to produce soluble phenoxy carboxylate, and additionally adding an alkaline substance during reaction; and adding water to the reactor to cool, adding acid to acidify, filtering and washing so as to obtain a wet phenoxy carboxylate material, and drying the wet material, thereby obtaining the phenoxy carboxylate herbicide original medicine. According to the method, after the reacting synthesis is completed, qualified products can be obtained through direct acidification; and due to the reduction of processing links, the influence on a producing environment is reduced, the water consumption is reduced, the synthesis is more environment-friendly, the problem of high water consumption in the traditional synthesis is solved, and the requirements on clean production are met, so that the method has an obvious economic benefit and a cost advantage.

Description

technical field [0001] The invention relates to a method for synthesizing the original drug of herbicides, in particular to a method for synthesizing the original drug of phenoxycarboxylic acid herbicides, and belongs to the technical field of pesticide synthesis. Background technique [0002] Phenoxycarboxylic acid herbicides are hormone-type systemic herbicides, which have strong physiological activity on plants, promote plant growth at low concentrations, and inhibit the growth of dicotyledonous plants at high concentrations. Deforms the plant until it dies. Because of its excellent characteristics of high efficiency, low toxicity, low residue, and no pollution to the environment, phenoxycarboxylic acid herbicides are now widely used. [0003] Phenoxycarboxylic acid herbicides include 2,4-D (2,4-dichlorophenoxyacetic acid), 2,4-DP (2-(2,4-dichlorophenoxy)-propionic acid), 2, 4-DB (2,4-dichlorophenoxybutyric acid), MCPA (2-methyl-4-chlorophenoxyacetic acid), MCPB (2-meth...

AI Technical Summary

Problems solved by technology

The process conditions of this method are mature, and it is convenient to realize large-scale production. The content of the obtained phenoxycarboxylic acids is > 96%, and the yield > 95%. However, the above-mentioned synthetic method has the following disadvantages: the above-mentioned synthetic method has the following disadvantages: 1. The synthesis reaction is incomplete, and after-treatment is required, the sodium salt is separated and washed, and then dissolved in salt and acidified to obtain a qualified product, which results in large water consumption, complicated process, large equipment investment, and high production cost.

2. In order to make the conversion of chlorophenol higher, the feeding ratio of chlorocarboxylic acid is higher. Usually, the molar ratio of chlorophenol is more than 1.3 times that of chlorophenol, which causes the consumption of chlorocarboxylic acid to be high

3. The solid-liquid separation process after synthesis has a great impact on the environment, especially the smell, which increases the pressure on environmental protection

This not only makes the process complicated, but also the reaction temperature of this method is high, and the requirements for equipment materials are strict. When the post-processing phenol is steamed, the pH must be strictly controlled, and the operation requirements are relatively high.

[0005] It can be seen from the above description that both the aqueous method and the non-aqueous method have certain shortcomings, so finding a new method to improve the synthetic conversion rate and simple process is the focus of the synthesis of phenoxycarboxylic acid pesticides