阅读说明：本技术 一种六氟丁二烯的制备方法 (Preparation method of hexafluorobutadiene ) 是由 张奎 黄天梁 黄荣保 于 2019-08-21 设计创作，主要内容包括：本发明公开了一种六氟丁二烯的制备方法。该制备方法包括如下步骤：(1)以三氟氯乙烯为原料在第一催化剂的作用下发生加氢反应,得到三氟乙烯；(2)三氟乙烯通入溴化反应釜与釜中的溴素进行溴化反应,得到1,2-二溴-1,1,2-三氟乙烷,然后脱溴化氢得到三氟溴乙烯；(3)三氟溴乙烯在装有溶剂、引发剂和锌粉的反应釜反应生成锌试剂三氟乙烯基溴化锌；(4)锌试剂三氟乙烯基溴化锌在第二催化剂的作用下发生偶联反应得到六氟丁二烯。本发明的制备方法具有能耗低,收率高,反应效率高等优点。(The invention discloses a preparation method of hexafluorobutadiene. The preparation method comprises the following steps: (1) performing hydrogenation reaction on chlorotrifluoroethylene serving as a raw material under the action of a first catalyst to obtain trifluoroethylene; (2) introducing trifluoroethylene into a bromination reaction kettle to perform bromination reaction with bromine in the kettle to obtain 1, 2-dibromo-1, 1, 2-trifluoroethane, and then removing hydrogen bromide to obtain trifluorobromoethylene; (3) reacting trifluorobromoethylene in a reaction kettle filled with a solvent, an initiator and zinc powder to generate zinc reagent trifluorovinyl zinc bromide; (4) and the zinc reagent trifluorovinyl zinc bromide is subjected to coupling reaction under the action of a second catalyst to obtain the hexafluorobutadiene. The preparation method has the advantages of low energy consumption, high yield, high reaction efficiency and the like.)

1. A preparation method of hexafluorobutadiene, which is characterized by comprising the following steps:

(1) performing hydrogenation reaction on chlorotrifluoroethylene serving as a raw material under the action of a first catalyst to obtain trifluoroethylene;

(2) introducing trifluoroethylene into a bromination reaction kettle to perform bromination reaction with bromine in the kettle to obtain 1, 2-dibromo-1, 1, 2-trifluoroethane, and then removing hydrogen bromide to obtain trifluorobromoethylene;

(3) reacting trifluorobromoethylene in a reaction kettle filled with a solvent, an initiator and zinc powder to generate zinc reagent trifluorovinyl zinc bromide;

(4) and the zinc reagent trifluorovinyl zinc bromide is subjected to coupling reaction under the action of a second catalyst to obtain the hexafluorobutadiene.

2. The method according to claim 1, wherein the first catalyst of step (1) is a supported metal catalyst; preferably, the active component of the supported metal catalyst is selected from one of Pt or Pb, and the carrier is one of activated carbon, aluminum trifluoride or aluminum oxide.

3. The method according to claim 1, wherein the step (2) is carried out by a photobromination reaction under the condition of ultraviolet light, and the wavelength of the ultraviolet light is 190nm to 315 nm.

4. The method for preparing hexafluorobutadiene according to claim 1, wherein the molar ratio of trifluoroethylene to bromine in step (2) is 1.05: 1.

5. The method according to claim 1, wherein the initiator of step (3) is a zinc complex; the solvent is an aprotic polar solvent, preferably N, N-Dimethylformamide (DMF); the zinc powder is activated zinc powder.

6. The preparation method of hexafluorobutadiene as claimed in claim 1, wherein the mass ratio of the trifluorobromoethylene, the solvent, the zinc powder and the initiator in the step (3) is 24-30: 80-130: 10-17: 9-13.

7. The method for preparing hexafluorobutadiene as claimed in claim 1, wherein the reaction temperature in step (3) is 40-60 ℃, the reaction pressure is 0-0.05MPa, and the reaction time is 1-4 h.

8. The method for preparing hexafluorobutadiene as claimed in claim 1, wherein the trifluorobromoethylene in step (3) is added into the reaction kettle in two batches, the trifluorobromoethylene with total amount of 1/4-1/3 is added, and the rest trifluorobromoethylene is added after the reaction is initiated.

9. The method according to claim 1, wherein the second catalyst in step (4) is one of cupric chloride and cupric bromide.

10. The method for preparing hexafluorobutadiene as claimed in claim 1, wherein the mass ratio of the zinc reagent to the second catalyst in the step (4) is 110-150: 13-19.

Technical Field

The invention relates to a preparation method of hexafluorobutadiene, in particular to a method for preparing hexafluorobutadiene by taking chlorotrifluoroethylene as a raw material.

Background

Hexafluorobutadiene, also known as perfluorobutadiene, HFBD for short, having the formula C₄F₆. Hexafluorobutadiene is an important monomer for synthetic resins and fluorine-containing substances. At present, the application of the hexafluorobutadiene is mainly focused on the plasma medium etching processing technology of the semiconductor products. With conventional plasma etching gas CF₄、C₂F₆、C₃F₈、NF₃Compared with C₄F₆Has faster etching speed, high etching selectivity and high aspect ratio. In addition, according to international convention requirements such as the kyoto protocol and the paris agreement and requirements of international low-carbon social construction, the electronic gas using the low-temperature chamber effect needs to be developed, and the GWP value of the hexafluorobutadiene is only 290, the atmospheric lifetime is only 1.9d, and the hexafluorobutadiene is a very green choice.

In recent years, there have been many studies on the synthesis of hexafluorobutadiene, and these are roughly classified into four types according to the raw materials:

1. CFCl (CFCl) (CFCl (1, 2-difluorodichloroethylene)) is used as a raw material;

2. with CF₂CFCl (chlorotrifluoroethylene) as a raw material;

3. with CF₂＝CF₂(tetrafluoroethylene) as a raw material;

4. halogenated hydrocarbons (halogenated ethane, halogenated butane) are used as raw materials.

Chinese patent CN105399599B discloses a method for preparing hexafluorobutadiene by reacting 1, 1-dichloro-1, 2, 2-trifluoroethane or 1, 2-dichloro-1, 1, 2-trifluoroethane in H₂In the atmosphere, carrying out hydrogenation dechlorination dimerization reaction on a supported metal catalyst, separating out the target product of the hexafluorobutadiene, and then carrying out thermal cracking on the obtained intermediate product of the hydrofluorochlorobutane to remove HCl so as to obtain the hexafluorobutadiene.

Chinese patent CN106495982B discloses a method for preparing hexafluorobutadiene by catalysis, which comprises the steps of carrying out reduction dechlorination on 1, 2-dichloro-1, 1, 2-trifluoroethane by zinc powder to obtain CF₂CHF gas phase intermediate productAdding into bromine to perform addition reaction to obtain CBrF₂CHBrF，CBrF₂CHBrF is evaporated in an evaporator to generate gas, one part of HBr is removed through a reaction tube filled with a first catalyst to generate bromotrifluoroethylene, and the bromotrifluoroethylene is subjected to two-step reaction under the action of zinc powder, a solvent and a second catalyst to generate hexafluoro-1, 3-butadiene.

However, the above methods for preparing hexafluorobutadiene from dichlorotrifluoroethane all have the problems of difficult raw material availability, low yield and difficult industrialization.

Disclosure of Invention

Based on the problems of the existing process for preparing the hexafluorobutadiene, the invention aims to provide a preparation method of the hexafluorobutadiene. The preparation method of the invention obtains the hexafluorobutadiene by strictly controlling the conditions of each process through the process steps of hydrogenation, bromination, coupling and the like.

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

a preparation method of hexafluorobutadiene, comprising the following steps:

(1) performing hydrogenation reaction on chlorotrifluoroethylene serving as a raw material under the action of a first catalyst to obtain trifluoroethylene;

(2) introducing trifluoroethylene into a bromination reaction kettle to perform bromination reaction with bromine in the kettle to obtain 1, 2-dibromo-1, 1, 2-trifluoroethane, and then removing hydrogen bromide to obtain trifluorobromoethylene;

(3) reacting trifluorobromoethylene in a reaction kettle filled with a solvent, an initiator and zinc powder to generate zinc reagent trifluorovinyl zinc bromide;

(4) and the zinc reagent trifluorovinyl zinc bromide is subjected to coupling reaction under the action of a second catalyst to obtain the hexafluorobutadiene.

The synthesis process comprises the following steps:

further, in the above production method, the first catalyst of the step (1) is a supported metal catalyst; preferably, the active component of the supported metal catalyst is selected from one of Pt or Pb, and the carrier is one of activated carbon, aluminum trifluoride or aluminum oxide.

Further, in the above production method, the molar ratio of chlorotrifluoroethylene to hydrogen of step (1) is 1: 1.1.

Further, in the above preparation method, the reaction temperature in the step (1) is 200-500 ℃.

Further, in the above preparation method, the step (2) is performed with a photobromination reaction under the condition of ultraviolet light, and the wavelength range of the ultraviolet light is 190nm to 315 nm.

Further, in the above production method, the molar ratio of the trifluoroethylene in the step (2) to the bromine is 1.05: 1.

Further, in the above production method, the initiator of the step (3) is a complex of zinc; the solvent is an aprotic polar solvent, preferably N, N-Dimethylformamide (DMF); the zinc powder is activated zinc powder.

Further, in the preparation method, the mass ratio of the trifluorobromoethylene, the solvent, the zinc powder and the initiator in the step (3) is 24-30: 80-130: 10-17: 9-13.

Further, in the preparation method, the reaction temperature of the step (3) is 40-60 ℃, the reaction pressure is 0-0.05MPa, and the reaction time is 1-4 h.

Further, in the preparation method, the trifluorobromoethylene in the step (3) is added into the reaction kettle in two batches, the trifluorobromoethylene with the total amount of 1/4-1/3 is added firstly, and the rest trifluorobromoethylene is added after the reaction is initiated.

Further, in the above preparation method, the second catalyst in the step (4) is one of copper chloride and copper bromide.

Further, in the preparation method, the mass ratio of the zinc reagent in the step (4) to the second catalyst is 110-150: 13-19.

Further, in the preparation method, the reaction temperature in the step (4) is-5 ℃ to 5 ℃, the reaction pressure is 0 MPa to 0.05MPa, and the reaction time is 1 h to 2 h.

Further, in the above production method, the production method further includes a rectification step.

The invention has the following characteristics:

(1) the invention takes the chlorotrifluoroethylene as the raw material, thereby reducing the reaction cost.

(2) 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.

(3) The trifluorobromoethylene is reacted in batches, so that the reaction yield is improved, and the reaction is mild.

(4) The preparation process of the hexafluorobutadiene has the advantages of low energy consumption, high yield, high conversion rate and high reaction efficiency.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention.

FIG. 2 is an apparatus for producing 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 and a 7-stirring device.

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 process flow of the invention is shown in figure 1:

the method comprises the steps of taking chlorotrifluoroethylene as a raw material, adding the chlorotrifluoroethylene into a metering tank for metering, allowing the metered chlorotrifluoroethylene to pass through a gas phase buffer tank, performing hydrogenation reaction in a heater, dehalogenating the obtained substance to obtain trifluoroethylene, storing the trifluoroethylene in a gas bag, compressing the trifluoroethylene by a compressor to obtain a trifluoroethylene liquid, adding bromine into the trifluoroethylene liquid for bromination to obtain 1, 2-dibromo-1, 1, 2-trifluoroethane, and performing alkali washing and dehalogenation to obtain the trifluoroethylene. Adding a zinc-containing reagent into the trifluorobromoethylene, removing zinc from a product, washing with water and alkali, and compressing to obtain a crude product of the hexafluorobutadiene. The crude product is rectified to obtain the electronic grade hexafluorobutadiene with the purity of 99.999 percent.

According to the process flow, the method is divided into a trifluoroethylene preparation section, a trifluoroethylene bromide preparation section, a zinc reagent trifluoroethylene zinc bromide preparation section, a coupling section and a rectification section.

In one embodiment of the present invention, the trifluoroethylene preparation section uses chlorotrifluoroethylene as a raw material to perform a hydrogenation reaction under the action of the first catalyst. The first catalyst is a supported metal catalyst; preferably, the active component of the supported metal catalyst is selected from one of Pt or Pb, and the carrier is one of activated carbon, aluminum trifluoride or aluminum oxide. Wherein the mol ratio of the chlorotrifluoroethylene to the hydrogen is 1:1.1, and the reaction temperature is 200-500 ℃.

In a specific embodiment of the invention, trifluoroethylene in a trifluorobromoethylene preparation working section is introduced into a bromination reaction kettle under an ultraviolet light condition (the ultraviolet light wavelength is 190 nm-315 nm) to perform a photobromination reaction with bromine in the kettle to obtain 1, 2-dibromo-1, 1, 2-trifluoroethane, and then dehydrobromination is performed to obtain trifluorobromoethylene. Wherein the molar ratio of the trifluoroethylene to the bromine is 1.05: 1.

The device for preparing 1, 2-dibromo-1, 1, 2-trifluoroethane at the trifluorobromoethylene preparation working section is shown in figure 2 and comprises a bromination reaction kettle 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 light-transmitting glass beads, and a stirring device 7 is further included in the bromination reaction kettle and used for fully stirring reaction raw materials.

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 to fully mix the introduced trifluoroethylene and the bromine, stopping feeding when the molar ratio of the trifluoroethylene to the bromine reaches 1-1.1: 1, and finishing the reaction.

In a specific embodiment of the invention, the number of the bromination reaction kettles is two, the two bromination reaction kettles are arranged in series, the product outlet 8 of the first bromination reaction kettle is communicated with the crude 1, 2-dibromo-1, 1, 2-trifluoroethane inlet 9 of the second bromination reaction kettle, the molar ratio of the recycled amount of the crude 1, 2-dibromo-1, 1, 2-trifluoroethane to bromine is 0.5-2: 1, and the residual crude 1, 2-dibromo-1, 1, 2-trifluoroethane is collected and subjected to post-treatment to obtain a 1, 2-dibromo-1, 1, 2-trifluoroethane product.

In a specific embodiment of the invention, in a zinc reagent trifluorovinyl zinc bromide preparation working section, trifluorobromoethylene with the total amount of 1/4-1/3 is introduced into a reaction kettle filled with a solvent, an initiator and zinc powder, initiation is carried out at a certain temperature, all trifluorobromoethylene raw materials are continuously added after initiation, heat preservation is carried out for a certain time after feeding is finished until the reaction is finished, and then solid-liquid separation is realized on reaction liquid through a liquid separating tank and a filter to obtain the zinc reagent trifluorovinyl zinc bromide.

According to the invention, through adding the trifluorobromoethylene in batches, the temperature-flushing amplitude can be reduced, the safety risk is improved, and the reaction yield is also favorably improved. The initial feeding of the trifluorobromoethylene is too little, the initiation time of the reaction is prolonged, even the initiation is not initiated, so that the total reaction time is prolonged, and even the normal reaction cannot be carried out; the initial feeding of the trifluorobromoethylene is too much, so that the initiation time can be shortened, but the temperature rising amplitude after initiation is increased, so that the retention time of the produced zinc reagent at high temperature is prolonged, the reaction risk is increased, and the yield is reduced. Therefore, the process determines the starting trifluorobromoethylene feed amount to be 1/4-1/3 of the total amount, and if the reaction is not initiated in the period, the reaction is initiated by other measures.

The initiator of the trifluorovinyl zinc bromide preparation section is a zinc complex; the solvent is an aprotic polar solvent, preferably N, N-Dimethylformamide (DMF), the purity is more than or equal to 99.5 percent, and the water content is less than 200 ppm; the zinc powder is activated zinc powder, the total zinc content is more than or equal to 99.5 percent, and the active zinc content is more than 97 percent.

Wherein the mass ratio of the trifluorobromoethylene to the solvent to the zinc powder to the initiator is 24-30: 80-130: 10-17: 9-13. The reaction temperature is 40-60 ℃, the reaction pressure is 0-0.05MPa, and the reaction time is 1-4 h.

Trifluorovinyl zinc bromide (zinc reagent) is an organic metal complex and is immediately decomposed into trifluoroethylene when meeting water or active protons. After the reaction is finished, the reaction product is stored in a solution, can be slowly decomposed after being placed for a long time at normal temperature, is quickly decomposed in a high-temperature environment, and is poor in stability. Therefore, it should be used as soon as possible after the reaction is completed.

The reaction in the preparation section of the trifluorovinyl zinc bromide is exothermic, the reaction needs an initiation process, the reaction initiation temperature is too high, the temperature is increased to a higher temperature after initiation, the decomposition of the product is accelerated, and the yield is reduced; the reaction starting temperature is too low, the reaction initiation is difficult, or more trifluorobromoethylene is needed for initiation, so that the temperature for flushing after initiation is higher, the safety risk is increased, and the reaction is not favorable. Therefore, through the small-scale test exploration, the reaction is preferably carried out, the initial temperature is controlled to be 45 ℃, the temperature is increased to 55 ℃ after the initiation, and then the temperature is rapidly reduced to 45 ℃ for reaction. Can meet the requirement of reaction initiation and can react at lower temperature.

In addition, the trifluorovinyl zinc bromide preparation section needs to pay attention to the trifluorovinyl bromide feeding speed, and the trifluorovinyl bromide feeding speed is too slow, so that the total reaction time is prolonged, and the retention time of the generated zinc reagent at high temperature after the reaction is initiated is prolonged, so that the reaction yield is reduced and the equipment capacity is reduced. The feeding of the trifluorobromoethylene is too fast, the introduced trifluorobromoethylene cannot be completely absorbed by a solvent, so that the system pressure is increased, the safety risk is increased, meanwhile, the reaction is exothermic, the reaction rate is high, the kettle temperature is easily difficult to control, the reaction parameters are unstable, the reaction heat preservation time is prolonged, and the yield is reduced. Taking a 1000L reaction kettle as an example, the feeding speed of the trifluorobromoethylene is preferably controlled to be 120-150 kg/h.

The parameter settings for the trifluorovinylzinc bromide preparation section can be as shown in table 1.

TABLE 1 List of parameters for preparation of trifluorovinyl zinc bromide

In a specific embodiment of the invention, zinc reagent trifluorovinyl zinc bromide in the coupling section is subjected to coupling reaction under the action of a second catalyst to obtain the hexafluorobutadiene. Wherein the second catalyst is one of cupric chloride and cupric bromide, and the purity is more than or equal to 98 percent. The mass ratio of the zinc reagent to the second catalyst is 110-150: 13-19. The reaction temperature is-5 ℃ to 5 ℃, the reaction pressure is 0 to 0.05MPa, and the reaction time is 1 to 2 hours. The coupling reaction is exothermic, but the exothermic quantity is not large, and can be controlled by the feeding speed, taking a 1000L reaction kettle as an example, the feeding speed of the zinc reagent is 550-750 kg/h. The reaction needs to be carried out at low temperature, the temperature has great influence on the reaction selectivity, the reaction temperature is too high, the contents of by-products trifluoroethylene and trifluorobromoethylene are increased, the product content is reduced, and the yield is reduced; the reaction temperature is too low, the conversion rate of raw materials is reduced, the process is slowed down, and the energy consumption is increased.

The parameter settings for the coupling section of the present invention can be as shown in table 2.

Table 2 summary of coupling section parameters

In one embodiment of the present invention, the distillation section is divided into two stages of distillation, and the parameters of the distillation section of the present invention can be set as shown in table 3.

TABLE 3 summary of parameters for rectification section

The electronic grade hexafluorobutadiene with the purity of 99.999 percent is prepared by rectification.

The total yield and conversion rate are not very high due to long process flow of the total reaction and complex partial reaction, the total yield reaches 55 percent, the conversion rate reaches 68 percent, but the process is extremely easy to industrialize.

The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core ideas. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.