CN111233619A - A kind of method for synthesizing 4-halogenated-1,1,2-trifluoro-1-butene - Google Patents

Abstract

The invention discloses a method for synthesizing 4-halogenated-1,1,2-trifluoro-1-butene. Specifically, polyhalogenated ethane is synthesized by addition reaction of chlorotrifluoroethylene and halogen, and then polyhalogenated ethane is reacted with ethylene under the action of a catalyst to synthesize polyhalogenated butane, and finally dehalogenated under the action of a reducing agent to synthesize 4 -Halo-1,1,2-Trifluoro-1-butene. The invention has the characteristics of simple synthesis method, high product purity and low preparation cost.

Description

A kind of method for synthesizing 4-halogenated-1,1,2-trifluoro-1-butene

technical field

The invention relates to a method for synthesizing 4-halogenated-1,1,2-trifluoro-1-butene, and belongs to the technical field of synthesis of pesticides and pharmaceutical intermediates.

Background technique

Fluorine-containing olefin compounds are widely used in the fields of pesticides and medicines. CN1359379A, WO0102378, and US5952359 disclose the application of several 4-halo-1,1,2-trifluoro-1-butenes in nematicidal pesticides. US2006/0052640 discloses a method for preparing 4-bromo-1,1,2-trifluoro-1-butene, but the raw materials used are not easy to obtain and the cost is high, so it needs to be further improved.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for synthesizing 4-halogenated-1,1,2-trifluoro-1-butene, so as to overcome the defects existing in the prior art.

The technical scheme adopted in the present invention is as follows: a method for synthesizing 4-halogenated-1,1,2-trifluoro-1-butene, comprising the following steps:

(1) Preparation of polyhalogenated ethanes

Put the 500ml three-necked flask into a low temperature bath, cool it to -50°C, add the halogen and the catalyst into the three-necked flask, then, stir, pass into chlorotrifluoroethylene, control the temperature not to be higher than -40°C, wait for the solution to fade, and the reaction is complete , to obtain a yellowish liquid, polyhalogenated ethane, and directly enter the next reaction;

Wherein, the halogen can be chlorine or liquid bromine or iodine, preferably chlorine, and the catalyst is benzophenone;

(2) Preparation of polyhalogenated butanes

Add the polyhalogenated ethane and the catalyst into the autoclave, replace the ethylene three times, control the ethylene pressure at 1-2MPa, and heat up. When the temperature rises to 50°C, a violent reaction begins in the autoclave, the temperature rises to 80-90°C, and the reaction temperature is controlled. No more than 120℃, after several times of pressing, the temperature did not rise significantly after the gas was charged, and after the gas was charged into 4MPa, after 16 hours of reaction, atmospheric distillation was performed to obtain polyhalogenated ethane and polyhalogenated butane;

Wherein, the catalyst is one of azoisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, di-tert-butyl peroxide, and dicumyl peroxide, preferably azoisobutyronitrile;

(3) Preparation of 4-halo-1,1,2-trifluoro-1-butene

Add the reducing agent to the alcoholic solvent, heat it to 50°C, drop in the polyhalogenated butane, react for 3h, control the temperature at 50°C-90°C, after the reaction is completed, continue to stir for 30 minutes, and distill under reduced pressure to obtain 4-halogenated Generation-1,1,2-trifluoro-1-butene, purity 96%.

Wherein, the reducing agent is iron powder or magnesium powder or zinc powder, preferably iron powder; the alcohol solvent is one of ethanol, n-butanol, isopropanol, ethylene glycol, and diethylene glycol, preferably ethylene glycol.

The beneficial effects obtained by the present invention are as follows: the present invention has the characteristics of easy availability of reaction raw materials, high yield, short steps, low cost, and suitability for industrial production.

Detailed ways

The following examples serve to illustrate the invention.

Example 1 Preparation of polyhalogenated ethanes

241g (3.4mol) of liquid chlorine and 3.4g (0.02mol) of benzophenone were added to a 500ml three-necked flask, cooled to -80°C, and passed through with chlorotrifluoroethylene. After the solution faded, the reaction was completed. Under reduced pressure distillation, the product 584g was obtained, the yield was 92%, and the purity GC was 98%. Changed to bromine, the yield was 94%. Replaced with iodine, the yield was 95%.

Example 2 Preparation of polyhalogenated butanes

1125g of polyhalogenated ethane and 15g of azobisisobutyronitrile were added to the autoclave, ethylene was replaced three times, then the ethylene pressure was controlled at 1MPa, and the temperature was increased. to 80-90°C, the pressure will be 0MPa at this time, continue to press to 1MPa, control the reaction temperature not to exceed 120°C, press for several times, the temperature does not rise significantly after the gas is charged, and the reaction is overnight after charging into 4MPa, and the normal pressure is fine. 480 g of polyhalogenated ethane and 350 g of polyhalogenated butane were distilled, with a purity of 93% and a yield of 77%.

Example 3 Synthesis of 4-halo-1,1,2-trifluoro-1-butene

Add 22.4g (0.4mol) iron powder to 200ml ethylene glycol, heat to 50℃, drop 90g polyhalogenated butane, react for 3h, control the temperature at 50℃-55℃, after the reaction, continue stirring for 30min, reduce the pressure Distillation to obtain 51 g of product, with a purity of 96% and a yield of 90% after calculation.

Claims (1)

1. a method for synthesizing 4-halogenated-1,1,2-trifluoro-1-butene, is characterized in that comprising the following steps: (1) Preparation of polyhalogenated ethanes Put the 500ml three-necked flask into a low temperature bath, cool it to -50°C, add the halogen and the catalyst into the three-necked flask, then, stir, pass into chlorotrifluoroethylene, control the temperature not to be higher than -40°C, wait for the solution to fade, and the reaction is complete , obtain a yellowish liquid, polyhalogenated ethane, directly enter the next step reaction; Wherein, the halogen is chlorine gas or liquid bromine or iodine, and the catalyst is benzophenone; (2) Preparation of polyhalogenated butanes Add polyhalogenated ethane and catalyst into the autoclave, replace ethylene three times, control the ethylene pressure at 1-2MPa, heat up, and when the temperature rises to 50°C, a violent reaction starts in the autoclave, and the reaction temperature is controlled not to exceed 120°C, after several times Pressing, the temperature does not rise significantly after the gas is charged, and after being charged into 4MPa, the reaction is performed for 16 hours, and the atmospheric rectification is performed to obtain polyhalogenated ethane and polyhalogenated butane; Wherein, the catalyst is one of azoisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, di-tert-butyl peroxide, and dicumyl peroxide; (3) Synthesis of 4-halo-1,1,2-trifluoro-1-butene Add the reducing agent to the alcoholic solvent, heat it to 50°C, add polyhalogenated butane dropwise, react for 3h, control the temperature at 50°C-90°C, after the reaction is completed, continue to stir for 30 minutes, and distill under reduced pressure to obtain 4-halogenated Substituted-1,1,2-trifluoro-1-butene; Wherein, the reducing agent is iron powder, magnesium powder or zinc powder; the alcohol solvent is one of ethanol, n-butanol, isopropanol, ethylene glycol and diethylene glycol.