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Preparation method for 2,2-dichloro-1,2-dibrom-1,1-difluoroethane

A technology of difluoroethane and trichloroethane, applied in 2, can solve problems such as being difficult to obtain, and achieve the effects of simple and easy method, mild reaction conditions, and easy-to-obtain raw materials

Inactive Publication Date: 2005-01-19
ZHEJIANG LANTIAN ENVIRONMENTAL PROTECTION HI TECH
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  • Abstract
  • Description
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Problems solved by technology

This method raw material 2,2-dichloro-1,1-dibromo-1,2-difluoroethane is not easy to obtain

Method used

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  • Preparation method for 2,2-dichloro-1,2-dibrom-1,1-difluoroethane

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[0025] 1. In a 500ml three-necked reaction flask equipped with a magnetic stirrer, a thermometer, a reflux condenser and a cooling condenser, drop into 240 grams of 25% NaOH aqueous solution and 1.0 gram of phase transfer catalyst tetrabutylammonium bromide, at a temperature of 20 to 20 169.5 grams of 2,2-difluoro-1,1,2-trichloroethane was added dropwise at 25°C, and the dropping time was controlled to be 2 hours. The content of the product 1,1-difluoro-2,2-dichloroethylene is 99.0% by weight, and 2,2-difluoro-1,1,2-trichloroethane is 1.0% by weight.

[0026] 2. In a 500ml three-necked reaction flask equipped with a magnetic stirrer, a thermometer and a reflux condenser, add 336 grams of liquid bromine, and dropwise add the 1,1-difluoro-2 , 268.7 grams of 2-dichloroethene, control the dropping time for 3 hours, after the dropping is completed, keep warm at 5-10°C for 2 hours, then raise the temperature to 50-55°C, and wash with 100ml of 5% NaOH aqueous solution for two times,...

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Abstract

The invention relates to a preparation method for 2,2-dichloro-1,2-dibrom-1,1-difluoroethane from 1,1-difluorine-1,2,2-trichloroethane at the presence of its 0.5-2.0% quaternary ammonium salt or quaternary phosphonium salt phase transition catalyst, through hydrogen chloride removal under alkaline condition at 0-80 deg. C to prepare 1,1-difluorine-2,2-dichloroethylene, charging 1.0-1.5 mol weight of bromine for reaction at 0-50 deg. C.

Description

technical field [0001] The invention relates to a preparation method of fluorine-containing organic compound 2,2-dichloro-1,2-dibromo-1,1-difluoroethane. Background technique [0002] 2,2-Dichloro-1,2-dibromo-1,1-difluoroethane is a precursor for the synthesis of alkyl brominated difluoroacetates, which are intermediates for pharmaceutical products . [0003] So far, only German patent 2,245,372 has recorded the preparation of 2,2-dichloro-1,1-dibromo-1,2-difluoroethane by catalytic isomerization under the action of aluminum halide 1,2-Dibromo-1,1-difluoroethane method. The raw material 2,2-dichloro-1,1-dibromo-1,2-difluoroethane for this method is not easily available. Contents of the invention [0004] The present invention aims at the deficiencies of the prior art, and develops a 2,2-dichloro-1,1-difluoro-1,2,2-trichloroethane through two steps of dehydrochlorination reaction and bromine addition reaction. - The method...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C17/04C07C17/35C07C19/14
Inventor 徐卫国陈先进
Owner ZHEJIANG LANTIAN ENVIRONMENTAL PROTECTION HI TECH
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