A kind of preparation method of diethyl methylphosphonite

Abstract

The invention discloses a preparation method of diethyl methylphosphonite, aiming to solve the problem that in the existing method, when ammonia gas is used as the acid-binding agent, the pH value of the reaction solution needs to be controlled between 7.0-8.5, accurately It is very difficult to control the pH value, and when the pH value is lower than that, a large amount of ethyl methylphosphinate by-products will be generated, and the use of organic amines as acid-binding agents has high toxicity, high price, and cumbersome recovery process. The problem of low recovery rates. The present invention uses methyl phosphine dichloride, ethanol and calcium oxide as main raw materials to prepare diethyl methyl phosphinate, which is a lower-cost diethyl methyl phosphonite suitable for industrial production. Methods of Esters Preparation. In the preparation of diethyl methylphosphonite, the present invention uses cheap calcium oxide instead of ammonia or organic amine as the acid-binding agent for the first time, which effectively reduces the production cost, and the calcium oxide is non-toxic, environmentally friendly, and has relatively Good economic value and social value.

Description

technical field [0001] The invention relates to the field of chemical industry, especially the field of pesticides and herbicides, in particular to a preparation method of diethyl methylphosphonite. Background technique [0002] Glufosinate-ammonium is a non-selective herbicide developed by Hoechst (now owned by Bayer), and it is also the second most resistant herbicide in genetically modified crops in the world. In recent years, with the delisting of paraquat and the increasingly prominent problem of glyphosate resistance, there is a wave of glufosinate-ammonium boom in China. [0003] Glufosinate-ammonium is mainly obtained through Michael reaction, Strecker reaction and hydrolysis reaction of the key intermediate diethyl methylphosphonite, acrolein and sodium cyanide. At present, the preparation methods of diethyl methylphosphonite mainly include: Grignard method, reduction method and esterification method. [0004] Patents EP0391329, CN102399239, CN102399240, CN1033740...

AI Technical Summary

Problems solved by technology

[0009] The purpose of the present invention is to: when ammonia gas is used as the acid-binding agent, the pH value of the reaction solution needs to be controlled between 7.0-8.5, and it is very difficult to accurately control the pH value, and when it is lower than this pH value, it will generate A large amount of ethyl methylphosphinate by-products, while using organic amines as acid-binding agents, there are problems such as high toxicity, high price, complicated recovery process, and low recovery rate. A kind of diethyl methylphosphinate is provided. Preparation