One-pot preparation method of 2,2-difluoro-1,3-benzodioxin

Abstract

The invention relates to a one-pot preparation method of 2,2-difluoro-1,3-benzodioxole. The one-pot preparation method of 2,2-difluoro-1,3-benzodioxole is characterized by comprising the following steps: adding piperonyl cyclonene, phosphorus oxychloride and phosphorus pentachloride in a lined polytetrafluoroethylene stainless steel bottle, rising temperature to reflux, ending the reaction when the content of piperonyl cyclonene taken as a raw material is detected to be less than 0.2% by GC, carrying out vacuum rectification on a reaction solution to distill off phosphorus trichloride which is a byproduct and phosphorus oxychloride taken as a solvent; cooling to the temperature of 0 to 5 DEG C after the vacuum rectification is finished, dropwise adding hydrogen fluoride liquid at the vacuum degree of minus 0.1 to minus 0.09MPa, then carrying out heat preservation and releasing the byproduct, namely hydrogen chloride; then dropwise adding a saturated sodium carbonate aqueous solution, adjusting the PH value of the solution to be 6.5 to 7.5, stirring and standing to be stratified, taking an organic layer and distilling to obtain a finished product, namely 2,2-difluoro-1,3-benzodioxole which is colorless and transparent liquid. The one-pot preparation method of 2,2-difluoro-1,3-benzodioxole disclosed by the invention has the advantages of low reaction temperature, high safety and improved yield.

Description

technical field [0001] The present invention relates to a preparation method of 2,2-difluoro-1,3-benzodioxol, in particular to a one-pot preparation method of 2,2-difluoro-1,3-benzodioxol . Background technique [0002] 2,2-difluoro-1,3-benzodioxol is a common chemical reagent used in large-scale industrial production, and it is an intermediate of medicine and pesticide; there are two main synthesis methods at this stage. [0003] Method 1. Use chlorine gas as the chlorination reagent, 3,4-dichloro-trifluorotoluene as the solvent, catalyze with ultraviolet light, and carry out the chlorination reaction. It needs to use a special reactor equipped with ultraviolet light irradiation, because the boiling point of the solvent is relatively high. High, 184.4°C, the reaction under reflux requires heat transfer oil as the heat transfer medium, and the energy consumption is high; the reaction is prone to produce polychlorinated impurities, after the chlorination reaction, the reacti...

AI Technical Summary

Problems solved by technology

[0003] Method 1. Use chlorine gas as the chlorination reagent, 3,4-dichloro-trifluorotoluene as the solvent, catalyze with ultraviolet light, and carry out the chlorination reaction. It needs to use a special reactor equipped with ultraviolet light irradiation, because the boiling point of the solvent is relatively high. High, 184.4°C, the reaction under reflux requires heat transfer oil as the heat transfer medium, and the energy consumption is high; the reaction is prone to produce polychlorinated impurities, after the chlorination reaction, the reaction solution is cooled to 0-3°C, and hydrogen fluoride is added dropwise , the fluorination reaction is over, the excess hydrogen fluoride is removed by heating, and the finished product 2,2-difluoro-1,3-benzodioxol is obtained by rectification; the recovery cost of solvent rectification in this preparation method is relatively high; the total yield is less than 83% , the preparation method of ultraviolet photocatalytic chlorination is easy to produce polychlorinated impurities. In addition, the solvent needs to be rectified and recycled, and the unit price is high, and the energy consumption is high, which leads to high production costs.

[0004] Method 2. Also use chlorine as the chlorination reagent, chlorobenzene and trifluorotoluene as the solvent, and use azobisisobutyronitrile as the catalyst to carry out reflux chlorination reaction. Since the catalyst decomposes at high temperature, it decomposes rapidly at 100°C, and the reaction It is difficult to control, and there are residual raw materials. After the reaction, dichloropipercycline is obtained by rectification, and the yield is less than 88%. The solvent is recovered and applied mechanically. Dichloropipercycline is added to trifluorotoluene and cooled to 0-3 ° C, and hydrogen fluoride is added dropwise. After the fluorination reaction is over, turn it into ice water to wash until neutral, and rectify to obtain the finished product 2,2-difluoro-1,3-benzodioxol, with a total yield of less than 80%. The reaction process of this preparation method is more difficult control, it is easy to produce incomplete reaction of raw materials, resulting in a decrease in yield and an increase in cost; in addition, dichloropipercycline is prone to air decomposition during rectification and transfer, which affects product yield

Images