Continuous production method for triethyl phosphite

Abstract

The invention discloses a continuous production method for triethyl phosphite. The method comprises the steps that absolute ethyl alcohol and phosphorus trichloride are taken as reaction raw materials, dimethylaniline and o-dichlorobenzene are taken as reaction solvent, ammonia is introduced while reacting is performed, and after reacting is finished, a product is directly delivered into a continuous distillation column to be processed through reduced pressure distillation to obtain crude triethyl phosphite; the rest materials are delivered into a washing column to be washed by adding hot water and then layered, an organic layer is delivered into a distillation column to be processed through distillation dewatering to be recycled by serving as solvent, a water layer is delivered into a cooling kettle to be cooled, ammonium chloride solids are crystallized out, and mother liquor is continuously used for washing the rest materials of distillation. After the obtained triethyl phosphite is rectified through a rectifying column, the purity is 99.5%-99.9%, and the obtained ammonium chloride can serve as an ammonium fertilizer raw material. The continuous production method has the advantages that a decomposition reaction can be prevented from occurring in the process that the triethyl phosphite participates washing, dewatering can be achieved only by simply distilling the mother liquor, a salt column does not need to be introduced for dewatering, generation of secondary solid waste can be avoided, pollution to the environment is greatly reduced, the labor intensity is low, and the production cost is low.

Description

technical field [0001] The invention relates to a method for preparing chemical substances, in particular to a method for producing triethyl phosphite with the advantages of high yield, stable quality, low energy consumption and low pollution. technical background [0002] Triethyl phosphite, also known as triethyl phosphite; triethyl phosphite (triethoxyphosphine), is mainly used as pesticide and pharmaceutical intermediates, used to prepare OB series fluorescent whitening agents, AE active esters, Glufosinate intermediates, various flame retardants, etc. Chinese patent CN1724546A uses benzene as a solvent, and in the presence of triethylamine, phosphorus trichloride and absolute ethanol are used as raw materials to synthesize and separate triethyl phosphite, which solves the problem of low production yield and low product purity. problem, but it needs to go through processes such as alkaline water washing and salt drying, the operation is cumbersome and the production eff...

AI Technical Summary

Problems solved by technology

Chinese patent CN1724546A uses benzene as a solvent, and in the presence of triethylamine, phosphorus trichloride and absolute ethanol are used as raw materials to synthesize and separate triethyl phosphite, which solves the problem of low production yield and low product purity. problem, but it needs to go through processes such as alkaline washing, salt drying, etc., the operation is cumbersome and the production efficiency is low

[0003] Chinese patent CN101624400A introduces a production method of triethyl phosphite, using pure benzene as a solvent and using triethylamine for continuous production, which has the advantages of large production capacity and stable product quality, but due to the use of highly toxic benzene as a solvent, and Both benzene and triethylamine need to be distilled out, which is potentially harmful to the environment and the health of on-site operators, and the production energy consumption is high. At the same time, a salt drying tower is required for drying. The treatment of the salt after absorbing water is cumbersome, resulting in Secondary pollution, not conducive to industrial production