Method for tubular continuous synthesis of (3-acetoxy-3-cyanopropyl)-methyl phosphinic acid alkyl ester

Abstract

The invention provides a method for tubular continuous synthesis of (3-acetoxy-3-cyanopropyl)-methyl phosphinic acid alkyl ester, which comprises the following steps: a) continuously feeding acetic acid-1-cyano-2-propenyl ester, methyl phosphinic acid alkyl ester and an initiator into a mixer, and mixing to obtain a mixed material; b) feeding the mixed material obtained in the step a) from the bottom of a vertical pipeline reactor, and reacting to obtain a reaction mixture; and c) feeding the reaction mixture obtained in the step b) into an evaporator, and purifying to obtain the (3-acetoxy-3-cyanopropyl)-methyl phosphinic acid alkyl ester. The method comprises the following steps: fully mixing reaction raw materials through a mixer, directly introducing the mixture into a vertical pipeline reactor, discharging the material from the upper part of the reactor, introducing the material into an evaporator, and carrying out low-temperature removal and distillation purification to obtain the (3-acetoxy-3-cyanopropyl)-methyl phosphinic acid alkyl ester, the method is simple in process steps, industrial control and continuous production are easy to realize, and the synthesized product is high in purity and good in yield.

Description

technical field [0001] The invention relates to the technical field of organic synthesis, more specifically, relates to a method for continuously synthesizing (3-acetoxy-3-cyanopropyl)-methylphosphinic acid alkyl ester in a tubular manner. Background technique [0002] (3-Acetoxy-3-cyanopropyl)-methylphosphonic acid alkyl ester is a key intermediate for the synthesis of glufosinate-ammonium, and the current patent literature synthesizes (3-acetoxy-3-cyanopropyl)-methyl The method of n-butyl phosphonate mainly adopts batch method to carry out. For example, the patent DE2849003A1 discloses phosphoric acid amino derivatives and their preparation methods. Under a nitrogen atmosphere and vigorous stirring, a mixture of tert-butyl peroctoate and acrolein cyanohydrin acetate is added dropwise to monoisobutyl methylphosphonite In the process, after the heat preservation reaction is finished, the excess monoisobutyl methylphosphonite is removed under reduced pressure, and then the r...

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Problems solved by technology

For example, the patent DE2849003A1 discloses phosphoric acid amino derivatives and their preparation methods. Under a nitrogen atmosphere and vigorous stirring, a mixture of tert-butyl peroctoate and acrolein cyanohydrin acetate is added dropwise to monoisobutyl methylphosphonite In the process, after the heat preservation reaction is finished, the excess monoisobutyl methylphosphonite is removed under reduced pressure, and then the residue is distilled under high vacuum; Staying and accumulating in the reactor for a long time will easily lead to the increase of by-products and there are certain safety hazards

In the patent CN110386950A, in the free radical addition step, the initiator is distributed, part of the intermediate methyl phosphinate mono-n-butyl is kept warm and part of the initiator is added, and acrolein cyanohydrin acetate and part of the The mixed liquid of the intermediate mono-n-butyl methyl phosphinate, and the mixed liquid of part of the intermediate mono-n-butyl methyl phosphinate and the remaining initiator are slowly pumped into the reactor for reaction at the same time; On the basis of the kettle process, the reaction temperature is maintained through material distribution and feed rate control, the process control is complicated, and the problem of the increase of by-products caused by the accumulation of reaction materials in the kettle cannot be fundamentally solved.

Patent CN106459110A adopts multi-stage reactors to carry out the reaction. In the first-stage reactor, firstly add methylphosphonous acid mono-n-butyl ester and initiator as substrates, and at the same time add acrolein cyanohydrin and methyl-phosphonous acid mono-n-butyl Ester mixture, methyl phosphonite mono-n-butyl ester and initiator mixture, after reacting for 2 hours, continue to add two streams of materials, release the substrate to the secondary reactor at the same time, continue feeding and discharging, and keep the primary reactor The liquid level is constant, and then the continuous mode is realized, which is called quasi-continuous mode; this process is a transformation of the original kettle-type batch process, the process operation is complicated, the equipment needs more, and at the same time, it cannot fundamentally avoid the process of continuous feeding and discharging of the kettle type. material backmixing problem

Patent CN108026122A adopts a discontinuous process to prepare (3-acetoxy-3-cyanopropyl)-methylphosphinic acid n-butyl mixed feed liquid, then add the feed liquid into the reactor, and then add ACA, MPE and the initiator are added to the reactor, while part of the reactor mixture is discharged to keep the volume of the mixture constant, and the time to maintain the material in the system is 4.0 hours; The problem of material backmixing in the process of continuous feeding and discharging of kettle

Patent CN112110954A discloses a method for synthesizing 3-(butoxymethylphosphoryl)-1-cyanopropyl acetate based on a microchannel reactor, using monobutyl methylphosphinate, 1-cyano -2-propenyl acetate is a raw material, which is continuously reacted under photocatalysis, and utilizes a microchannel reactor to prepare (3-acetoxy-3-cyanopropyl)-n-butyl methylphosphinate; Combining the integrated heating system and lighting system on the microchannel reactor is a great challenge to the material and processing requirements of the equipment, resulting in very high equipment costs and operating costs when it is applied in industrial production

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