CN1566048A - Preparation method for 2,2-dichloro-1,2-dibrom-1,1-difluoroethane - Google Patents
Preparation method for 2,2-dichloro-1,2-dibrom-1,1-difluoroethane Download PDFInfo
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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
The invention relates to a preparation method of a fluorine-containing organic compound 2, 2-dichloro-1, 2-dibromo-1, 1-difluoroethane.
Background
2, 2-dichloro-1, 2-dibromo-1, 1-difluoroethane is a precursor for synthesizing brominated alkyl difluoroacetate, and the brominated alkyl difluoroacetate is an intermediate of medical products.
So far, only german patent 2,245,372 describes a process for the preparation of 2, 2-dichloro-1, 2-dibromo-1, 1-difluoroethane by catalytic isomerization of 2, 2-dichloro-1, 1-dibromo-1, 2-difluoroethane under the action of an aluminum halide. The raw material of themethod, namely the 2, 2-dichloro-1, 1-dibromo-1, 2-difluoroethane, is not easy to obtain.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the method for synthesizing the 2, 2-dichloro-1, 2-dibromo-1, 1-difluoroethane by the two steps of dehydrochlorination reaction and bromine addition reaction of the 1, 1-difluoro-1, 2, 2-trichloroethane, which has the advantages of easily obtained raw materials, simple and convenient method and easy realization of industrial production.
The preparation method of 2, 2-dichloro-1, 2-dibromo-1, 1-difluoroethane comprises two steps of dehydrochlorination reaction of 1, 1-difluoro-1, 2, 2-trichloroethane to synthesize 1, 1-difluoro-2, 2-dichloroethylene and addition reaction of 1, 1-difluoro-2, 2-dichloroethylene and bromine:
dehydrochlorination reaction in step 1
Under the action of phase transfer catalyst and alkaline compound, 1, 1-difluoro-1, 2, 2-trichloroethane can produce dehydrochlorination reaction to produce 1, 1-difluoro-2, 2-dichloroethylene.
Suitable phase transfer catalysts for the process according to the invention may be quaternary ammonium salts or quaternary phosphonium salts, with quaternary ammonium salts being preferred and tetrabutylammonium bromide being most preferred. The dosage of the phase transfer catalyst is 0.5-2.0% of the weight of the 1, 1-difluoro-1, 2, 2-trichloroethane.
In the process of the present invention, the reaction temperature is suitably from 0 to 80 ℃, preferably from 0 to 50 ℃, more preferably from 20 to 25 ℃.
In the method, the alkali isused for absorbing the hydrogen chloride removed in the reaction, so that the reaction is more favorable for proceeding towards the positive direction, and the reverse reaction is not generated, namely the reverse addition reaction of the intermediate olefin and the hydrogen chloride is not generated. Suitable basic compounds are alkali metal hydroxides, preferably NaOH. The addition amount of the alkali is to ensure that the reactant is always in an alkaline range with the pH value of more than 10, and the molar ratio of the proper alkaline compound to the 1, 1-difluoro-1, 2, 2-trichloroethane is controlled to be 1.1-2.0, preferably 1.4-1.5.
In the method, the reaction time is not strictly required, and the gas chromatography analysis tracking is only used for ensuring that the 1, 1-difluoro-1, 2, 2-trichloroethane can completely convert light. The reaction time is preferably controlled to 0.5 to 8 hours, more preferably 4 to 5 hours.
In the method, the boiling point of the raw material 1, 1-difluoro-1, 2, 2-trichloroethane is 72 ℃ under normal pressure, the boiling point of the intermediate 1, 1-difluoro-2, 2-dichloroethylene is 19 ℃, the two are easy to fractionate and separate, during synthesis, only a reflux condenser is arranged above a reactor, and then a cooling condenser is connected to continuously separate the intermediate, the purity of the intermediate can reach more than 99 percent, and the intermediate can be used for the next reaction without any treatment.
Step 2 bromine addition reaction
The 1, 1-difluoro-2, 2-dichloroethylene obtained from the reaction in the step 1 can easily undergo an addition reaction with bromine to produce 2, 2-dichloro-1, 2-dibromo-1, 1-difluoroethane.
According to the method, the reaction temperature is low, the reaction rate is slow, and the reaction needs longer time to complete; when the reaction temperature is high, the yield is lowered due to the low boiling point of 1, 1-difluoro-2, 2-dichloroethylene and the volatility of bromine. The bromination reaction is suitably carried out at a temperature of from 0 to 50 ℃ and preferably from 0 to 25 ℃ and most preferably from 5 to 10 ℃.
In the method of the invention, the 1, 1-difluoro-2, 2-dichloroethylene is expensive, so the bromine excess method is adopted to ensure the completion of the addition reaction. The molar ratio of bromine to 1, 1-difluoro-2, 2-dichloroethylene is suitably controlled to be in the range of 1.0 to 1.5, preferably 1.05 to 1.1.
In the method of the invention, the reaction time is not strictly required, as long as the complete conversion of 1, 1-difluoro-2, 2-dichloroethylene into light can be ensured. The reaction time is preferably controlled to be 1 to 10 hours, more preferably 4 to 6 hours.
In the method, the crude product obtained after the addition reaction is neutralized by alkali, washed by water, statically layered, and removed of the upper water layer to obtain the 2, 2-dichloro-1, 2-dibromo-1, 1-difluoroethane product with the content of more than 99 percent.
The method is simple and easy to implement, the reaction condition is mild, the raw materials are easy to obtain, the industrial scale-up production is easy, and the product 2, 2-dichloro-1, 2-dibromo-1, 1-difluoroethane is mainly used for medicine production and also can be used for production of plant protection products.
In the method, raw material 2, 2-difluoro-1, 1, 2-trichloroethane, intermediate 1, 1-difluoro-2, 2-dichloroethylene and product 2, 2-dichloro-1, 2-dibromo-1, 1-difluoroethane are subjected to online sampling by a Hewlett Packard (HP 6890) gas chromatograph, and a chromatographic column is HP-FFAP, the length of the chromatographic column is 50m, the inner diameter of the chromatographic column is 0.32mm, the nitrogen flow rate is 0.8 ml/min, the hydrogen flow rate is 40 ml/min, and the air flow rate is 400 ml/min. The gas chromatographic conditions were 70 ℃ for 7 minutes, followed by a programmed temperature increase to 150 ℃ at a rate of 10 ℃/minute for an additional 10 minutes.
The present invention is further illustrated by the following examples, but the scope of the present invention is not limited to these examples.
Examples
Firstly, 240 g of 25 percent NaOH aqueous solution and 1.0 g of phase transfer catalyst tetrabutylammonium bromide are put into a 500ml three-mouth reaction bottle provided with a magnetic stirring device, a thermometer, a reflux condenser and a cooling condenser, 169.5 g of 2, 2-difluoro-1, 1, 2-trichloroethane is dripped at the reaction temperature of 20-25 ℃, the dripping time is controlled to be 2 hours, the heat preservation reaction is carried out for 2 hours after the dripping is finished, 125 g of product is collected, and the sampling analysis is carried out, wherein the content of the 1, 1-difluoro-2, 2-dichloroethylene of the product is 99.0 percent by weight, and the content of the 2, 2-difluoro-1, 1, 2-trichloroethane is 1.0 percent by weight.
Adding 336 g of liquid bromine into a 500ml three-mouth reaction bottle provided with a magnetic stirring device, a thermometer and a reflux condenser, dropwise adding 268.7 g of 1, 1-difluoro-2, 2-dichloroethylene obtained by the reaction in the step 1 at the reaction temperature of 5-10 ℃, controlling the dropwise adding time to be 3 hours, after the dropwise adding is finished, preserving the temperature for 2 hours at the temperature of 5-10 ℃, then raising the temperature to 50-55 ℃, washing twice with 100ml of aqueous solution of 5% NaOH and twice with 200ml of water to obtain 574 g of the product 2, 2-dichloro-1, 2-dibromo-1, 1-difluoroethane with the purity of 99.6%.
Claims (4)
1. A process for producing 2, 2-dichloro-1, 2-dibromo-1, 1-difluoroethane, which comprises dehydrochlorinating 1, 1-difluoro-1, 2, 2-trichloroethane with a phase transfer catalyst and an alkali compound to produce 1, 1-difluoro-2, 2-dichloroethylene, and then subjecting 1, 1-difluoro-2, 2-dichloroethylene to addition reaction with bromine.
2. The process for producing 2, 2-dichloro-1, 2-dibromo-1, 1-difluoroethane according to claim 1, wherein 1, 1-difluoro-1, 2, 2-trichloroethane is reacted at 0 to 80 ℃ for 0.5 to 8 hours by adding an alkali metal hydroxide in a molar ratio of 1.1 to 2.0 to 1, 1-difluoro-1, 2, 2-trichloroethane in the presence of a quaternary ammonium salt or a quaternary phosphonium salt phase transfer catalyst in an amount of 0.5 to 2.0% by weight of the 1, 1-dichloro-1, 2-trichloroethane, and bromine is added to the 1, 1-difluoro-2, 2-dichloroethylene in a molar ratio of 1.0 to 1.5 and the 1 to 10 hours are reacted at 0 to 50 ℃.
3. The preparation method according to claim 1 or 2, characterized in that the dehydrochlorination reaction of 1, 1-difluoro-1, 2, 2-trichloroethane uses tetrabutyl ammonium bromide as catalyst, NaOH as alkali metal hydroxide, the molar ratio of alkali to 1, 1-difluoro-1, 2, 2-trichloroethane is 1.4-1.5, and the reaction temperature is 0-50 ℃ for 4-5 hours; bromine is added to the obtained 1, 1-difluoro-2, 2-dichloroethylene in a molar ratio of 1.05 to 1.1, and the reaction is carried out at 0 to 25 ℃ for 4 to 6 hours.
4. The preparation method according to claim 1 or 2, wherein the dehydrochlorination reaction temperature of 1, 1-difluoro-1, 2, 2-trichloroethane is 20-25 ℃; the bromine addition reaction temperature of the 1, 1-difluoro-2, 2-dichloroethylene is 5-10 ℃.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 03145545 CN1223559C (en) | 2003-07-01 | 2003-07-01 | Preparation method for 2,2-dichloro-1,2-dibrom-1,1-difluoroethane |
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| CN 03145545 CN1223559C (en) | 2003-07-01 | 2003-07-01 | Preparation method for 2,2-dichloro-1,2-dibrom-1,1-difluoroethane |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102395547A (en) * | 2009-04-17 | 2012-03-28 | 纳幕尔杜邦公司 | Improved process for the preparation of halo-olefins |
| CN102863313A (en) * | 2011-07-06 | 2013-01-09 | 中化蓝天集团有限公司 | Resource utilization method of tail gas from trifluoroethylene production |
| CN105384596A (en) * | 2015-11-13 | 2016-03-09 | 巨化集团技术中心 | Preparation method of vinylidene fluoride (VDF) |
-
2003
- 2003-07-01 CN CN 03145545 patent/CN1223559C/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102395547A (en) * | 2009-04-17 | 2012-03-28 | 纳幕尔杜邦公司 | Improved process for the preparation of halo-olefins |
| CN102863313A (en) * | 2011-07-06 | 2013-01-09 | 中化蓝天集团有限公司 | Resource utilization method of tail gas from trifluoroethylene production |
| CN105384596A (en) * | 2015-11-13 | 2016-03-09 | 巨化集团技术中心 | Preparation method of vinylidene fluoride (VDF) |
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| CN1223559C (en) | 2005-10-19 |
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