Method using fluidized bed to synthesize methyl phosphonic dichloride

Abstract

The invention discloses a method using a fluidized bed to synthesize methyl phosphonic dichloride (MDP). The method mainly includes: using a heat exchanger and a mixing preheater to mix phosphorus trichloride, auxiliaries and methane in the presence of fluidized gas and preheat the mixture to preset temperature, and allowing the mixture to enter a fluidized bed reactor in a gas state to perform reaction in the presence of a catalyst; subjecting the gas passing the reactor to primary condensation and secondary condensation, collecting liquid, and feeding the liquid into an MDP rectifying towerto perform rectifying so as to obtain MDP with the content being not smaller than 98%; drying noncondensable gas which passes a primary condenser and a secondary condenser and is absorbed by a water washing and alkaline washing tower in a drying tower, and allowing the noncondensable gas to reenter the reaction system after pressure swing adsorption impurity removing. The method is low in raw material cost and safe to operate; the fluidized bed reactor is used, radiating convenience is achieved, even bed layer internal temperature is achieved, control easiness is achieved, the occurrence of side reaction and the generation of solid impurities such as yellow phosphorus and coke are inhibited effectively, and product purity is increased.

Description

technical field [0001] The invention belongs to the technical field of chemical synthesis, and in particular relates to a method for synthesizing methylphosphine dichloride in a fluidized bed. Background technique [0002] Pure methylphosphine dichloride is a colorless transparent liquid with a boiling point of 81.5°C. It is an extremely versatile organic phosphine intermediate, which can be used to synthesize pesticides, medicines, flame retardants and other chemicals, such as the new high-efficiency herbicide glufosinate-ammonium. The chemical properties of methylphosphine dichloride are extremely active, and it will explode when it encounters water. The pure product is easily oxidized in the air. It is not easy to store, and it is difficult to buy in the market. [0003] There are no less than a hundred articles and patents on the synthesis of methylphosphine dichloride. At present, there are mainly 3 routes: (1) methane and phosphorus trichloride (2) ternary complexes -...

AI Technical Summary

Problems solved by technology

Route (1): Using methane and phosphorus trichloride as raw materials, there are many current literature reports, such as patent US4518538. The disadvantage of this reaction is that the reaction conditions are harsh, the reaction temperature is about 600 ° C, the energy consumption is large, and the reaction pressure is also high. Above 3MPa, industrial equipment is difficult to reach; the disadvantage of route (2) is that the raw material aluminum trichloride is difficult to recycle, it needs to consume a lot of solvent, and the complex reduction process will generate solid waste, and the pressure on environmental protection is great; route (3): if Patent US3840576, the disadvantage of this reaction is that the steps are slightly longer, the total yield is not high, and the formed complex intermediate is extremely unstable, and the operation is dangerous