阅读说明：本技术 一种1,2-二溴-1,1,2-三氟乙烷的制备方法及装置 (Preparation method and device of 1, 2-dibromo-1, 1, 2-trifluoroethane ) 是由 张林溪 张奎 朱军伟 于 2019-07-25 设计创作，主要内容包括：本发明公开了一种1,2-二溴-1,1,2-三氟乙烷的制备方法及装置。本发明通过在紫外光下,三氟乙烯液体通入溴化反应釜与釜中的溴素进行光溴化反应,得到1,2-二溴-1,1,2-三氟乙烷粗品,经后处理得到1,2-二溴-1,1,2-三氟乙烷产品。解决了溴加成反应放热导致投料缓慢的问题,具有反应平稳,反应速度快等优点。(The invention discloses a method and a device for preparing 1, 2-dibromo-1, 1, 2-trifluoroethane. Under ultraviolet light, trifluoroethylene liquid is introduced into a bromination reaction kettle to carry out a photobromination reaction with bromine in the kettle, so that a 1, 2-dibromo-1, 1, 2-trifluoroethane crude product is obtained, and a 1, 2-dibromo-1, 1, 2-trifluoroethane product is obtained through post-treatment. Solves the problem of slow feeding caused by heat release of bromine addition reaction, and has the advantages of stable reaction, high reaction speed and the like.)

1. A preparation method of 1, 2-dibromo-1, 1, 2-trifluoroethane is characterized in that under ultraviolet light, trifluoroethylene liquid is introduced into a bromination reaction kettle to carry out photobromination reaction with bromine in the kettle to obtain a 1, 2-dibromo-1, 1, 2-trifluoroethane crude product, and the 1, 2-dibromo-1, 1, 2-trifluoroethane product is obtained through aftertreatment.

2. the method for preparing 1, 2-dibromo-1, 1, 2-trifluoroethane according to claim 1, wherein the molar ratio of trifluoroethylene to bromine is 1 to 1.1: 1.

3. The method for preparing 1, 2-dibromo-1, 1, 2-trifluoroethane according to claim 2, wherein the molar ratio of trifluoroethylene to bromine is 1.05: 1.

4. The method for preparing 1, 2-dibromo-1, 1, 2-trifluoroethane according to claim 1, wherein the crude 1, 2-dibromo-1, 1, 2-trifluoroethane is partially recycled to the photobromination reaction.

5. The preparation method of 1, 2-dibromo-1, 1, 2-trifluoroethane according to claim 1, wherein the molar ratio of the crude 1, 2-dibromo-1, 1, 2-trifluoroethane to bromine is 0.5 to 2: 1.

6. The method for preparing 1, 2-dibromo-1, 1, 2-trifluoroethane according to claim 1, wherein the wavelength of the ultraviolet light is in the range of 190 to 315 nm.

7. An apparatus for preparing 1, 2-dibromo-1, 1, 2-trifluoroethane according to any one of claims 1 to 6, comprising a bromination reaction kettle, wherein the bromination reaction kettle is provided with a bromine inlet, a trifluoroethylene inlet and an ultraviolet light inlet, the ultraviolet light inlet is communicated with an illumination channel, the illumination channel is cylindrical, the side wall of the illumination channel is provided with more than two illumination ports, an ultraviolet light emitter is arranged outside the illumination ports, and the interior of the illumination channel is filled with light-transmitting glass beads.

8. The apparatus of claim 7, wherein the illumination channel is connected to a condenser above the illumination channel.

9. The device according to claim 7, wherein the number of the bromination reaction kettles is two, the two bromination reaction kettles are arranged in series, and an outlet above a condenser of the first bromination reaction kettle is communicated with a trifluoroethylene inlet of the second bromination reaction kettle.

10. The apparatus of claim 7, wherein the bromination reaction kettle further comprises a stirring device.

Technical Field

The invention relates to bromine addition reaction, in particular to a method and a device for preparing 1, 2-dibromo-1, 1, 2-trifluoroethane.

Background

The bromine addition reaction belongs to electrophilic addition, bromine molecules are polarized into polar molecules with one end carrying micro positive charges and the other end carrying micro negative charges under the influence of the outside, the positive end of the polar molecules reacts with double bonds of olefin to initially form a pi coordination compound, and then covalent bond heterolysis is carried out to obtain a sigma complex with positive charges and bromide ions.

1, 2-dibromo-1, 1, 2-trifluoroethane is an important intermediate for synthesizing hexafluorobutadiene, which is generally obtained by bromine addition reaction of trifluoroethylene with liquid bromine, and the main reaction formula is as follows:

CF₂＝CFH+Br₂→CF₂BrCFBrH。

For example, chinese patent CN106495982B2 discloses that trifluoroethylene is washed with water and alkali, and then is introduced into liquid bromine for reaction, after the reaction is completed, the color of the liquid bromine is brown and gradually becomes lighter, and CHF ═ CF₂And Br₂Complete reaction conversion to CF₂BrCFBrH。

However, the reaction is exothermic, so that the reaction of directly reacting trifluoroethylene with liquid bromine has obvious exothermicity, the feeding speed of the reaction is influenced, and the reaction takes longer time.

In order to overcome the defects, the invention develops the preparation method of the 1, 2-dibromo-1, 1, 2-trifluoroethane, and the method controls the reaction heat release, enables the reaction to be more stable and accelerates the reaction speed by recovering part of products to participate in bromine addition reaction and carrying out photobromination under the ultraviolet light condition.

Disclosure of Invention

The invention aims to provide a method and a device for preparing 1, 2-dibromo-1, 1, 2-trifluoroethane. The preparation method solves the problem of slow feeding caused by heat release of bromine addition reaction, and has the advantages of stable reaction, high reaction speed and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

A preparation method of 1, 2-dibromo-1, 1, 2-trifluoroethane comprises the steps of introducing trifluoroethene liquid into a bromination reaction kettle under ultraviolet light to perform a photobromination reaction with bromine in the kettle to obtain a 1, 2-dibromo-1, 1, 2-trifluoroethane crude product, and performing aftertreatment to obtain a 1, 2-dibromo-1, 1, 2-trifluoroethane product.

Further, the molar ratio of the trifluoroethylene to the bromine is 1-1.1: 1; preferably, the molar ratio of trifluoroethylene to bromine is 1.05: 1.

Further, the crude product of the 1, 2-dibromo-1, 1, 2-trifluoroethane is partially recycled to the photobromination reaction.

Further, the molar ratio of the 1, 2-dibromo-1, 1, 2-trifluoroethane crude product to bromine is 0.5-2: 1; preferably, the molar ratio of the crude 1, 2-dibromo-1, 1, 2-trifluoroethane to bromine is 1:1.

Furthermore, the wavelength range of the ultraviolet light is 190-315nm, and a straight tube type ultraviolet mercury lamp with the power of 30-100 watts is adopted.

The invention also provides a device for preparing the 1, 2-dibromo-1, 1, 2-trifluoroethane, which comprises a bromination reaction kettle, wherein the bromination reaction kettle is provided with a bromine inlet, a trifluoroethylene inlet and an ultraviolet light inlet, the ultraviolet light inlet is communicated with an illumination channel, the illumination channel is cylindrical, the side wall of the illumination channel is provided with more than two illumination ports, an ultraviolet light emitter is arranged outside the illumination ports, and the interior of the illumination channel is filled with transparent glass beads.

Further, the upper part of the illumination channel is connected with a condenser for preventing trifluoroethylene from escaping.

Furthermore, the number of the bromination reaction kettles is two, the two bromination reaction kettles are connected in series, and an outlet above a condenser of the first bromination reaction kettle is communicated with a trifluoroethylene inlet of the second bromination reaction kettle. The outlet above the condenser of the invention is part of unreacted trifluoroethylene which is introduced into the second bromination reaction kettle, thus improving the utilization rate of trifluoroethylene.

Further, a stirring device is also arranged in the bromination reaction kettle.

The invention has the following characteristics:

(1) The trifluoroethene and bromine are subjected to the photobromination reaction under the ultraviolet light condition, so that the reaction speed is increased, and the reaction time is shortened.

(2) The invention recycles part of the 1, 2-dibromo-1, 1, 2-trifluoroethane crude product, continues to participate in the photobromination reaction, is beneficial to reducing the reaction heat release, quickens the feeding speed and improves the production efficiency.

(3) The invention reasonably controls the technological parameters, and has higher yield of more than 97 percent.

Drawings

FIG. 1A schematic diagram of the apparatus for preparing 1, 2-dibromo-1, 1, 2-trifluoroethane according to the present invention.

FIG. 2 is a schematic diagram of the apparatus for preparing 1, 2-dibromo-1, 1, 2-trifluoroethane according to the present invention.

The device comprises a 1-bromination reaction kettle, a 2-bromine inlet, a 3-trifluoroethylene inlet, a 4-ultraviolet light inlet, a 5-illumination channel, a 6-illumination port, a 7-stirring device and a 8-product outlet.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs.

The device for preparing 1, 2-dibromo-1, 1, 2-trifluoroethane comprises a bromination reaction kettle 1 as shown in figure 1, wherein the bromination reaction kettle is provided with a bromine inlet 2, a trifluoroethylene inlet 3 and an ultraviolet light inlet 4, the ultraviolet light inlet 4 is communicated with an illumination channel 5, the illumination channel 5 is cylindrical, the side wall of the illumination channel 5 is provided with more than two illumination ports 6, an ultraviolet light emitter is arranged outside the illumination ports 6, the illumination channel is filled with transparent glass beads, the bromination reaction kettle also comprises a stirring device 7 for fully stirring reaction raw materials, and a crude product of 1, 2-dibromo-1, 1, 2-trifluoroethane is introduced into the bottom of the bromination reaction kettle 1 through a product outlet 8 and recycled to the photobromination reaction.

In one embodiment of the invention, the upper part of the illumination channel is connected with a condenser for preventing trifluoroethylene from escaping.

The ultraviolet light of the ultraviolet light emitter has the wavelength range of 190-315nm, and adopts a straight tube type ultraviolet mercury lamp with the power of 30-100W.

The bromination reactor of the invention is an enamel kettle, and the specification can be 200L or other.

Taking a bromination reactor with the specification of 200L as an example, the process for preparing the 1, 2-dibromo-1, 1, 2-trifluoroethane comprises the following steps: firstly, conveying bromine into a bromination reaction kettle from a bromine metering tank, then introducing trifluoroethylene into the bromination reaction kettle at a feeding speed of 10-20kg/h, simultaneously opening a stirring device, stirring reaction raw materials, fully mixing the introduced trifluoroethylene with the bromine, stopping feeding when the molar ratio of the trifluoroethylene to the bromine reaches 1-1.1: 1, wherein the molar ratio of the recycling amount of a 1, 2-dibromo-1, 1, 2-trifluoroethane crude product to the bromine is 0.5-2: 1, collecting the residual 1, 2-dibromo-1, 1, 2-trifluoroethane crude product, and carrying out post-treatment to obtain a 1, 2-dibromo-1, 1, 2-trifluoroethane product.

In one embodiment of the present invention, the number of the bromination reaction kettles is two, the two bromination reaction kettles are arranged in series, and the outlet above the condenser of the first bromination reaction kettle is communicated with the trifluoroethylene inlet of the second bromination reaction kettle, as shown in fig. 2.