Preparation method for difluoroethylene carbonate

Abstract

The invention discloses a preparation method for difluoroethylene carbonate. The method comprises the following steps: step 1, adding front cut fraction of vinylene carbonate and an organic solvent into a first reaction kettle, performing mixing and dissolving completely, introducing a nitrogen gas, wherein the mass fraction of vinylene carbonate in the front cut fraction of the vinylene carbonateis 30%-60%, performing heating to the temperature of 20-50 DEG C, adding liquid bromine dropwise or introducing a chlorine gas, performing an addition reaction, after the reaction is completed, performing desolventizing, performing refining to obtain a pure product of dibromoethylene carbonate or a pure product of dichloroethylene carbonate, and putting the pure product into a second reaction kettle for standby application; step 2, adding an organic solvent into the second reaction kettle until mixing and dissolving are performed completely, then adding a fluorinating reagent, performing a reaction, adding triethylamine to make the reaction liquid system weakly acidic, heating the second reaction kettle until the temperature is 50-70 DEG C, and keeping the temperature until a reaction isfinished, so as to obtain a crude product; and step 3, performing vacuum rectification on the crude product to obtain the target product difluoroethylene carbonate. The method provided by the invention has the advantages that the target product has high purity and a high yield, can reach an electronic grade, and fully utilizes a waste liquid.

Description

technical field [0001] The invention relates to the technical field of additives for lithium battery electrolytes, in particular to a preparation method of bisfluoroethylene carbonate. Background technique [0002] Difluoroethylene carbonate is a kind of lithium battery electrolyte additive. The addition of bisfluoroethylene carbonate can improve the cycle performance and low-temperature performance of the electrolyte, and can also significantly increase the flash point of the electrolyte. [0003] At present, the preparation methods for preparing bisfluoroethylene carbonate mainly contain the following types. 1. Using dichloroethylene carbonate as a raw material, carry out a fluorination reaction with a fluorinating reagent to obtain bisfluoroethylene carbonate. The defect of this method is: many side reactions, the yield is too low, it is not easy to purify, and the rectification process is difficult. 2. Using vinylene carbonate as raw material and fluorine gas as fluor...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that there are many side reactions, the yield is too low, it is not easy to purify, and the rectification process is difficult

The disadvantages of this method are: high cost of raw materials, easy corrosion of equipment, high equipment requirements, not suitable for industrial production

[0004] At present, there is still a problem in the production: the crude product of vinylene carbonate forward distillation (the content of vinylene carbonate is 30% ~ 60%) is relatively cumbersome to deal with, and the treatment cost is high, and it is usually treated as waste liquid