Preparation technique of ethyl difluoroacetate

Abstract

The invention discloses a preparation technique of ethyl difluoroacetate. The preparation technique comprises the following steps: sequentially adding halogenated ethyl difluoroacetate, triethylamine, a solvent and a catalyst into a high-pressure reaction kettle; replacing air in the reaction kettle with nitrogen, replacing with hydrogen, and heating to perform hydrogenation reaction until the kettle pressure reaches the standard value; when the kettle pressure drops, repeatedly introducing hydrogen until the kettle pressure no longer drops; and finally, carrying out rectification reaction, carrying out normal-pressure rectification operation on the obtained product in a glass bottle to separate out the product ethyl difluoroacetate, and carrying out filtration and water washing on the kettle bottom material to recover the catalyst for the reaction next time. By adopting the halogenated ethyl difluoroacetate as the raw material, the preparation technique of ethyl difluoroacetate has the advantages of simple preparation process, high product purity (at least 99.5%) and high yield (at least 95%), and the catalytic efficiency of the palladium-carbon catalyst does not obviously descend after the palladium-carbon catalyst is recovered 10 times, thereby enhancing the benefits of the enterprise.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and in particular relates to a preparation process of ethyl difluoroacetate. Background technique [0002] Ethyl difluoroacetate is an important pharmaceutical, pesticide and chemical intermediate. [0003] At present, there are many methods for preparing ethyl difluoroacetate, including the following methods: [0004] Method 1, EP0694523 discloses a preparation method of ethyl difluoroacetate, which is to add tetrafluoroethylene and methanol under the catalysis of a catalyst to synthesize methoxytetrafluoroethane, methoxytetrafluoroethane Catalytic cracking to obtain difluoroacetyl fluoride, and then esterify with ethanol to obtain ethyl difluoroacetate. [0005] Method 2, JP7242587 discloses a preparation method of ethyl difluoroacetate, which involves reacting tetrafluoroethylene, diethylamine and water in an autoclave to obtain N,N-diethyldifluoroacetamide, N, N-diethyldifluoroac...

AI Technical Summary

Problems solved by technology

[0007] The above-mentioned methods all have some problems in industrialized production. The route using tetrafluoroethylene as raw material, tetrafluoroethylene is not easy to obtain, requires high equipment, and the production process is risky; using difluoroethylene as raw material, oleum oxidation process, there are Low yield, serious equipment corrosion, large amount of three wastes, and high cost; most of the above methods and other methods reported in patents have the problem of scale-up production, which is not conducive to industrial production

[0008] Method 4, in order to find a process route suitable for industrial production, JP06228043 patent literature discloses the synthesis of N, N-diethyl dichloroacetamide with dichloroacetic acid chloride and diethylamine in toluene solvent, and then with potassium fluoride Synthesis of N,N-diethyldifluoroacetamide by fluorination in ethylene glycol, followed by hydrolysis with potassium hydroxide and esterification of ethanol to prepare ethyl difluoroacetate, but this method has a long process route and a total yield of only 47 %

In the CN102311343 patent literature, some improvements have been made to the above-mentioned process. Sulfolane is used to replace ethylene glycol, and the two-step reaction of hydrolysis and esterification is directly esterified in one step. Although this process has made some improvements, there are still some problems, such as One-step amidation reaction, using diethylamine as the reactant and acid-binding agent, the amount of diethylamine used is large, resulting in a large amount of amine salt, the recovery of diethylamine is difficult, the recovery rate is low, and the smell is very strong; the second step of fluorination Reaction, high temperature reaction at 145-150°C, the intermediate will decompose at high temperature, and the yield is low; the third step uses a one-pot method to produce a large amount of by-product ether and tar; the above reasons cause the overall yield to be low and the amount of three wastes to be large

Images