阅读说明：本技术 六氟-1,3-丁二烯的制备方法 (Preparation method of hexafluoro-1, 3-butadiene ) 是由 丁晨 李汉生 都荣礼 王鑫 王伟 牛韦 朱辉 张岩 田丁磊 左春雨 于 2020-12-28 设计创作，主要内容包括：本发明属于有机合成技术领域,具体涉及一种六氟-1,3-丁二烯的制备方法,以R22为原料,裂解制备TFE,TFE与Br-2在一定比例,一定条件下制备生成二溴四氟乙烷,二溴四氟乙烷与TFE在一定温度下,锌粉及DMF与甲苯组合溶剂条件下,反应制备生成六氟-1,3-丁二烯,反应后收集气相样品,用GC色谱分析,其中六氟-1,3-丁二烯比例占85％以上。该方法具备所用原料简单易得,价格低廉,工艺制备过程简单安全,产品收率高等优点。(The invention belongs to the technical field of organic synthesis, and particularly relates to a preparation method of hexafluoro-1, 3-butadiene, which takes R22 as a raw material to prepare TFE, TFE and Br by cracking 2 Dibromo tetrafluoroethane is prepared and generated under certain conditions in a certain proportion, dibromo tetrafluoroethane and TFE react under certain temperature and the condition of zinc powder, DMF and methylbenzene combined solvents to prepare hexafluoro-1, 3-butadiene, a gas phase sample is collected after reaction, and the gas phase sample is analyzed by GC, wherein the proportion of hexafluoro-1, 3-butadiene is more than 85%. The method has the advantages of simple and easily-obtained raw materials, low cost, simple and safe process, and high product yieldHigh advantage.)

1. A preparation method of hexafluoro-1, 3-butadiene is characterized in that: the method comprises the following steps:

(1) performing cracking reaction on difluorochloromethane serving as a raw material and steam to obtain tetrafluoroethylene;

(2) reacting tetrafluoroethylene with liquid bromine under the action of a catalyst to generate dibromotetrafluoroethane;

(3) tetrafluoroethylene and dibromotetrafluoroethane react to generate hexafluoro-1, 3-butadiene under the action of zinc powder dissolved in a solvent.

2. The process for producing hexafluoro-1, 3-butadiene as claimed in claim 1, wherein: the cracking reaction temperature in the step (1) is 600-900 ℃.

3. The process for producing hexafluoro-1, 3-butadiene as claimed in claim 1, wherein: in the step (2), the molar ratio of the liquid bromine to the tetrafluoroethylene is 1:1-1:5, and the reaction temperature is 60-150 ℃.

4. The process for producing hexafluoro-1, 3-butadiene as claimed in claim 1, wherein: the catalyst in the step (2) is activated carbon which needs to be activated before use, and the treatment method comprises the steps of firstly carrying out acidification treatment, then drying by nitrogen at 100 ℃ and 250mL/min, and then gradually heating to 400 ℃ for drying, wherein the heating rate is 10 ℃/min.

5. The process for producing hexafluoro-1, 3-butadiene as claimed in claim 1, wherein: in the step (3), the molar ratio of the tetrafluoroethylene to the dibromotetrafluoroethane is 1:1-1:7, the reaction temperature is 50-120 ℃, and the reaction time is 1-3 h.

6. The process for producing hexafluoro-1, 3-butadiene as claimed in claim 1, wherein: and (3) treating the zinc powder before use, wherein the treatment method comprises the steps of washing by using 20% hydrochloric acid, washing by using chloroform or acetone, filtering, and drying at 200 ℃ for 3 hours.

7. The process for producing hexafluoro-1, 3-butadiene as claimed in claim 1, wherein: in the step (3), the solvent is one or more of DMF, benzene or toluene.

8. The process for producing hexafluoro-1, 3-butadiene as claimed in claim 1, wherein: the method comprises the following steps:

(1) introducing difluorochloromethane serving as a raw material and steam into a cracking reactor A for cracking reaction, then separating and purifying to obtain tetrafluoroethylene, and introducing the tetrafluoroethylene into a reactor B and a reactor C respectively;

(2) introducing liquid bromine and tetrafluoroethylene into a reactor B together, reacting under the action of a catalyst, separating and purifying to obtain dibromotetrafluoroethane, and introducing the dibromotetrafluoroethane into a reactor C;

(3) and (2) dissolving zinc powder in a solvent, putting the solvent into a reactor C, reacting tetrafluoroethylene with dibromotetrafluoroethane under the action of the zinc powder, and collecting a product to obtain the hexafluoro-1, 3-butadiene.

Technical Field

The invention belongs to the technical field of organic synthesis, and particularly relates to a preparation method of hexafluoro-1, 3-butadiene.

Background

The hexafluoro-1, 3-butadiene has higher market value and wide industrial application. The downstream of the industrial-grade product can be used as raw materials of products such as fluorine-containing fine chemicals, fluorine-containing medical pesticide intermediates and the like. Meanwhile, the modified polytetrafluoroethylene can be used as a monomer for preparing homopolymer polyhexafluorobutadiene, and can also be used for preparing a copolymer with other olefin monomers as an elastomer resin with excellent electrical property. With the development of the electronic semiconductor industry, the excellent GWP value of a high-purity product is considered to be an effective substitute for the traditional fluorine-containing electronic special gas in the aspect of large-scale integrated circuits.

At present, many researchers at home and abroad research the preparation of hexafluoro-1, 3-butadiene. At present, three intermediate methods are mainly used as main preparation methods, namely, a tetrahalohexafluorobutane intermediate is prepared and formed, a trifluorovinyl metal halide intermediate is prepared, and a dihalohexafluorocyclobutane intermediate is prepared. For the synthesis of intermediates, researchers have adopted various research methods.

US2894043 reports that dichlorodifluoroethylene is used as a raw material to be dimerized under fluorine gas to synthesize an intermediate tetrachlorohexafluorobutane, and then dechlorination is carried out under the action of zinc powder to obtain the target product hexafluoro-1, 3-butadiene. The yield of the reaction system is only 30 percent, and fluorine gas is used, so that the system is dangerous, and the reaction system has more by-products and difficult product separation. US2676193 optimizes the process by using uv light instead of dimerization, and performing addition reaction with chlorine gas to obtain hexachlorotetrafluorobutane, followed by exchange reaction with fluorochlorohydrin to obtain tetrachlorohexafluorobutane. The four steps of the reaction are long in telomerization time consumption, and the purification is difficult even if a plurality of byproducts are generated.

JP2001114710 reports a method for synthesizing hexafluorobutadiene from tetrafluoroethylene as a raw material. Tetrafluoroethylene is mainly used as a raw material and is added with bromine to obtain tetrafluorodibromoethane; dibromotetrafluoroethane undergoes rearrangement under the catalysis of Lewis acid. Then under the action of zinc powder, obtaining a zinc trifluoroethylene bromide reagent; and (3) coupling zinc trifluoroethylene bromide under the action of a catalyst to obtain the hexafluoro-1, 3-butadiene. The process has mild reaction, but the consumption of zinc reagent is large, the unit consumption of raw materials is high, and the storage of the raw material tetrafluoroethylene is difficult and independent.

WO2006026400 reports a process for the preparation of hexafluoro-1, 3-butadiene from trifluorobromoethylene. The tetrafluoroethane is used as a raw material to react with the zinc chloride and the lithium diisopropylamide to form the zinc trichloride. Then coupling to obtain hexafluoro-1, 3-butadiene. The method has the advantages that the total yield can reach 60-70%, the synthesis steps are simple, but lithium diisopropylamide is adopted in the reaction, the price is high, the production process is dangerous, and the method is not suitable for large-scale industrialization. CN104829415 also introduces a method for synthesizing hexafluoro-1, 3-butadiene, taking HFC-134a as raw material, firstly preparing dibromo tetrafluoroethane intermediate, then reacting in N, N-dimethylformamide solution under the action of zinc powder to obtain hexafluoro butadiene, although the cost of reaction solvent and catalyst is lower, the safety is higher, but the relative conversion rate is lower, the condition needs further optimization.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the method for preparing the hexafluoro-1, 3-butadiene overcomes the defects of the prior art, adopts cheap and easily-obtained industrial raw material difluorochloromethane (R22) as the raw material, and efficiently prepares the hexafluoro-1, 3-hexafluoro-butadiene through three steps; high product yield, safe process and suitability for industrial production.

The preparation method of hexafluoro-1, 3-butadiene comprises the following steps:

(1) performing cracking reaction on difluorochloromethane (R22) serving as a raw material and water vapor to obtain Tetrafluoroethylene (TFE);

(2) tetrafluoroethylene and liquid bromine (Br)₂) Under the action of a catalyst, dibromotetrafluoroethane is generated by reaction;

(3) tetrafluoroethylene and dibromotetrafluoroethane react to generate hexafluoro-1, 3-butadiene under the action of zinc powder dissolved in a solvent.

Wherein:

the cracking reaction temperature in the step (1) is 600-900 ℃.

In the step (2), the molar ratio of the liquid bromine to the tetrafluoroethylene is 1:1-1:5, and the reaction temperature is 60-150 ℃, preferably 80-120 ℃.

The catalyst in the step (2) is activated carbon which needs to be activated before use, and the treatment method comprises the steps of firstly carrying out acidification treatment, then drying by nitrogen at 100 ℃ and 250mL/min, and then gradually heating to 400 ℃ for drying, wherein the heating rate is 10 ℃/min.

In the step (3), the molar ratio of the tetrafluoroethylene to the dibromotetrafluoroethane is 1:1-1:7, the reaction temperature is 50-120 ℃, and the reaction time is 1-3 h.

And (3) treating the zinc powder before use, wherein the treatment method comprises the steps of washing by using 20% hydrochloric acid, washing by using chloroform or acetone, filtering, and drying at 200 ℃ for 3 hours.

In the step (3), the solvent is one or more of DMF, benzene or toluene, preferably a composition solvent of DMF and toluene.

Preferably, the preparation method of hexafluoro-1, 3-butadiene comprises the following steps:

(1) introducing difluorochloromethane serving as a raw material and steam into a cracking reactor A for cracking reaction, then separating and purifying to obtain tetrafluoroethylene, and introducing the tetrafluoroethylene into a reactor B and a reactor C respectively;

(2) introducing liquid bromine and tetrafluoroethylene into a reactor B together, reacting under the action of a catalyst, separating and purifying to obtain dibromotetrafluoroethane, and introducing the dibromotetrafluoroethane into a reactor C;

(3) and (2) dissolving zinc powder in a solvent, putting the solvent into a reactor C, reacting tetrafluoroethylene with dibromotetrafluoroethane under the action of the zinc powder, and collecting a product to obtain the hexafluoro-1, 3-butadiene.

Compared with the prior art, the invention has the following beneficial effects:

1. the raw materials of the invention are cheap and easily available, and the source is convenient.

2. The invention has safe synthetic process and is suitable for industrial production.

3. The method is simple and convenient, and the product yield is high.

Drawings

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

Detailed Description

The present invention is further illustrated by, but is not limited to, the following specific examples.

Example 1

And (3) introducing the R22 into the cracking reactor A at 100mL/min and 10mL/min of steam, setting the reaction temperature at 750 ℃, reacting for a period of time, and separating and purifying by washing with water and alkali to obtain pure TFE. Placing 20mL of treated activated carbon into a reactor B, opening a TFE valve leading to the reactor B, and setting the flow of TFE to be 30mL/min and Br₂And introducing the mixture into a reactor B at the flow rate of 10mL/min, reacting at the temperature of 90 ℃ for 1h, and then passing through a buffering and water alkali washing device and a cooling collector to obtain a product. The product was subjected to GC analysis and the collection contained 40% dibromotetrafluoroethane.

Pouring zinc powder into 100mL of 20% hydrochloric acid solution, stirring for a period of time, washing with acetone, drying at 200 ℃ for 3h, dissolving in DMF solvent, and placing in a reaction kettle C for later use. And (3) introducing the product in the collector into the reaction kettle C at the rate of 20mL/min, opening a TFE valve, introducing the product into the reaction kettle C at the rate of 40mL/min, setting the reaction temperature at 70 ℃, reacting for 2 hours, and collecting the product through a condensation collector. The product was subjected to GC analysis, and the hexafluoro-1, 3-butadiene content in the product was collected to be 78%.

Example 2

And (3) introducing the R22 into the cracking reactor A at 100mL/min and 10mL/min of steam, setting the reaction temperature at 750 ℃, reacting for a period of time, and separating and purifying by washing with water and alkali to obtain pure TFE. Placing 20mL of treated activated carbon into a reactor B, opening a TFE valve leading to the reactor B, and setting the flow of TFE to be 30mL/min and Br₂And introducing the mixture into a reactor B at the flow rate of 10mL/min, reacting at the temperature of 90 ℃ for 1h, and then passing through a buffering and water alkali washing device and a cooling collector to obtain a product. The product was subjected to GC analysis and the collection contained 40% dibromotetrafluoroethane.

Pouring zinc powder into 100mL of 20% hydrochloric acid solution, stirring for a period of time, washing with acetone, drying at 200 ℃ for 3h, dissolving in a mixed solvent of DMF and toluene, and placing in a reaction kettle C for later use. And (3) introducing the product in the collector into the reaction kettle C at the rate of 20mL/min, opening a TFE valve, introducing the product into the reaction kettle C at the rate of 40mL/min, setting the reaction temperature at 70 ℃, reacting for 2 hours, and collecting the product through a condensation collector. The product was subjected to GC analysis, and the hexafluoro-1, 3-butadiene content thereof was collected in the product to be 87%.

Example 3

And (3) introducing the R22 into the cracking reactor A at 100mL/min and 10mL/min of steam, setting the reaction temperature at 750 ℃, reacting for a period of time, and separating and purifying by washing with water and alkali to obtain pure TFE. Placing 20mL of treated activated carbon into a reactor B, opening a TFE valve leading to the reactor B, and setting the flow of TFE to be 30mL/min and Br₂And introducing the mixture into a reactor B at the flow rate of 10mL/min, reacting at the temperature of 90 ℃ for 1h, and then passing through a buffering and water alkali washing device and a cooling collector to obtain a product. The product was subjected to GC analysis and the collection contained 40% dibromotetrafluoroethane.

Pouring zinc powder into 100mL of 20% hydrochloric acid solution, stirring for a period of time, washing with acetone, drying at 200 ℃ for 3h, dissolving in a mixed solvent of DMF and toluene, and placing in a reaction kettle C for later use. And (3) introducing the product in the collector into the reaction kettle C at the rate of 20mL/min, opening a TFE valve, introducing the product into the reaction kettle C at the rate of 40mL/min, setting the reaction temperature at 100 ℃, and collecting the product through a condensation collector after reacting for 2 hours. The product was subjected to GC analysis, and the hexafluoro-1, 3-butadiene content thereof was collected as 83% in the product.

Of course, the foregoing is only a preferred embodiment of the invention and should not be taken as limiting the scope of the embodiments of the invention. The present invention is not limited to the above examples, and equivalent changes and modifications made by those skilled in the art within the spirit and scope of the present invention should be construed as being included in the scope of the present invention.