A method and device for preparing hexafluoro-1,3-butadiene

Abstract

The invention discloses a kind of preparation method and device of hexafluoro-1,3-butadiene, the preparation method is that raw material 1,3-butadiene and / or chloro-1,3-butadiene are mixed with anhydrous hydrogen fluoride in a certain ratio and put into electrolyzer, the mixed liquid to be electrolyzed contacts the positive and negative electrodes of electrolyzer, controls the positive and negative electrode DC voltage at 2-10V, the mixed liquid temperature of electrolyzer under the conditions of 10 DEG C to 5 DEG C, carries out electrolytic fluorination substitution reaction;The gas phase product condensed and collected by the first outlet of electrolyzer top, the liquid phase product cooled and collected by the second outlet of electrolyzer bottom, obtains crude product hexafluoro-1,3-butadiene, then carries out purification treatments such as alkali cleaning, washing, drying to crude product, obtains target product hexafluoro-1,3-butadiene.The present invention is simple to operate, raw materials are easy to obtain, technology is mature, safe and reliable, and is suitable for industrialized production.

Description

Technical Field

[0001] The invention discloses a preparation method and device of hexafluoro-1,3-butadiene, belonging to the field of organic fluoride synthesis. Background Art

[0002] Hexafluoro-1,3-butadiene has a high market value and a wide range of industrial applications. It can be used as a raw material for fluorinated fine chemicals, fluorinated pharmaceuticals, pesticide intermediates, and other products. In the global electronic gas market, hexafluoro-1,3-butadiene is primarily used as an etching gas. During plasma etching, it can quickly form a low-density, thin fluorocarbon polymer protective film on the material surface. It also has moderate etching strength. Under suitable process conditions, it can achieve near-vertical etching, forming pores with a diameter of less than 0.1μm after etching, thereby achieving superior anisotropic etching effects. With the development of the electronic semiconductor industry, hexafluoro-1,3-butadiene, due to its excellent performance, has become an effective alternative to traditional fluorinated electronic specialty gases in large-scale integrated circuits.

[0003] At present, the traditional preparation of hexafluoro-1,3-butadiene mainly adopts chemical synthesis method.

[0004] Patent US2894043 reports that dichlorodifluoroethylene is used as a raw material, dimerized under fluorine gas to synthesize the intermediate tetrachlorohexafluorobutane, and then dechlorinated under the action of zinc powder to obtain the target product hexafluoro-1,3-butadiene.

[0005] Patent WO2005023734 reports that 1,4-dichlorobutene is chlorinated to obtain 1,2,3,4-tetrachlorobutane, which is then fluorinated with fluorine gas under the catalysis of sodium fluoride to obtain tetrachlorotetrafluorobutane. Under nitrogen protection, tetrachlorotetrafluorobutane is dechlorinated with zinc powder in a dioxane solvent to produce hexafluoro-1,3-butadiene.

[0006] Patent JP2001114710 reports a method for synthesizing hexafluorobutadiene from tetrafluoroethylene. The method involves adding bromine to tetrafluoroethylene to produce tetrafluorodibromoethane. The tetrafluorodibromoethane undergoes a Lewis acid-catalyzed rearrangement. Subsequently, zinc powder is reacted to produce trifluoroethylene zinc bromide. This trifluoroethylene zinc bromide, in the presence of a catalyst, undergoes a coupling reaction to produce hexafluoro-1,3-butadiene.

[0007] Patent WO2006026400 reports a method for preparing hexafluoro-1,3-butadiene from trifluoroethylene bromide, wherein tetrafluoroethane is used as a raw material and reacts with zinc chloride and lithium diisopropylamide to form zinc chloride trichloride, which is then coupled to obtain hexafluoro-1,3-butadiene.

[0008] Patent CN104829415 also introduces a method for synthesizing hexafluoro-1,3-butadiene. Using HFC-134a as a raw material, tetrafluorodibromoethane intermediate is first prepared, and then hexafluoro-1,3-butadiene is obtained by reaction in N,N-dimethylformamide solution under the action of zinc powder.

[0009] However, traditional chemical synthesis methods generally have many reaction steps and a complex reaction process. The reaction requires a catalyst to proceed, which makes it difficult to reuse the catalyst during post-processing and causes environmental pollution. The large amount of solvents used and the recovery of the solvent after the reaction is completed poses a safety hazard and increases production costs. Summary of the Invention

[0010] In view of the problems existing in the prior art, the present invention provides a method and device for preparing hexafluoro-1,3-butadiene, which is an electrochemical synthesis method.

[0011] The technical solution of the present invention is:

[0012] The invention discloses a method for preparing hexafluoro-1,3-butadiene. The method comprises the following steps: mixing raw materials 1,3-butadiene and / or chloro-1,3-butadiene with anhydrous hydrogen fluoride in a certain proportion and adding the mixture into an electrolytic cell. The mixed liquid to be electrolyzed contacts the positive and negative electrodes of the electrolytic cell. Under the conditions of a DC voltage of 2-10V between the positive and negative electrodes and a temperature of the mixed liquid in the electrolytic cell of -10°C to 5°C, an electrolytic fluorination substitution reaction is carried out.

[0013] The raw material is 1,3-butadiene and / or chloro-1,3-butadiene. The chloro-1,3-butadiene can be monochloro-1,3-butadiene to hexachloro-1,3-butadiene, that is, the number of hydrogen replaced by chlorine is 1 to 6, preferably chloro-1,3-butadiene, and more preferably hexachloro-1,3-butadiene.

[0014] Under DC voltage, electrons electrolyze anhydrous hydrogen fluoride into active fluoride anions and hydrogen cations. The fluoride anions undergo fluorination substitution reactions on the hydrogen atoms on the 1,3-butadiene molecule or the chlorine atoms and hydrogen atoms on the chloro-1,3-butadiene molecule to generate hexafluoro-1,3-butadiene.

[0015] When the raw materials are 1,3-butadiene and anhydrous hydrogen fluoride, the product of electrolytic fluorination at the positive electrode is hexafluoro-1,3-butadiene, and hydrogen is produced at the negative electrode at the same time; when the raw materials are chloro-1,3-butadiene and anhydrous hydrogen fluoride, the product of electrolytic fluorination at the positive electrode is hexafluoro-1,3-butadiene, and hydrogen and hydrogen chloride are produced at the negative electrode at the same time.

[0016] Preferably, the mass of the raw material 1,3-butadiene and / or chloro-1,3-butadiene accounts for 1-10% of the total mass of the raw material and the anhydrous hydrogen fluoride, and more preferably 5-8%.

[0017] Preferably, the electrolytic fluorination reaction is carried out for 12-24 hours.

[0018] Preferably, the DC voltage of the positive and negative electrodes of the electrolytic fluorination substitution reaction is 2-8V, more preferably 3-5V.

[0019] Preferably, the gaseous product flowing out of the first outlet at the top of the electrolytic cell is condensed and collected, while the liquid product flowing out of the second outlet at the bottom of the electrolytic cell is cooled and collected to obtain a crude hexafluoro-1,3-butadiene product. When the temperature of the mixed liquid in the electrolytic cell is controlled between -10°C and 5°C, the fully fluorinated hexafluoro-1,3-butadiene, due to its high specific gravity and reduced solubility in anhydrous hydrogen fluoride, will settle to the bottom of the electrolytic cell. The majority of the crude hexafluoro-1,3-butadiene product is obtained by cooling and collecting the liquid product. The temperature of the mixed liquid in the electrolytic cell is preferably between -8°C and 0°C.

[0020] When the mixed liquid temperature of the electrolytic cell is high, for example, controlled at 6°C to 19.5°C, most of the crude hexafluoro-1,3-butadiene product is obtained by condensing and collecting the gaseous products. However, under higher temperature conditions, the yield of hexafluoro-1,3-butadiene is relatively low.

[0021] The methods for controlling the temperature of the electrolytic cell can be: liquid phase circulation heat extraction, electrolytic cell jacket circulating cooling water heat extraction, electrolytic cell jacket chilled water circulation water heat extraction, electrolytic cell cooling coil circulating water, chilled water heat extraction and other methods.

[0022] Preferably, the purification and refining process of the collected crude hexafluoro-1,3-butadiene product comprises the following steps: firstly alkali washing and water washing the crude hexafluoro-1,3-butadiene product, and then drying the alkali-washed and water-washed product.

[0023] The present invention also relates to a device for preparing hexafluoro-1,3-butadiene, comprising an electrolytic cell, wherein the positive electrode material used in the electrolytic cell is metallic nickel or a metallic nickel-based composite material, more preferably metallic nickel N8; the negative electrode material is one of metallic nickel, a metallic nickel-based composite material, metallic iron, and an iron-based composite material; the positive and negative electrodes are in the form of a single electrode pair or a multi-electrode pair in which the positive and negative electrodes are arranged at intervals.

[0024] Preferably, the positive and negative electrodes of the electrolytic cell are connected to a power supply device capable of providing a DC voltage.

[0025] Preferably, the electrolytic cell is provided with a cooling jacket, a cooling coil or a liquid phase cooling circulation system with a heat exchanger for controlling the temperature of the liquid in the electrolytic cell.

[0026] Preferably, the top of the electrolytic cell is provided with a feed inlet and a first outlet, and the bottom of the electrolytic cell is provided with a second outlet;

[0027] The first outlet of the electrolytic cell is connected to a condenser, and the condenser is provided with a gas phase tail gas outlet and a liquid phase outlet;

[0028] The second outlet of the electrolytic cell is connected to a sight glass and a cooler in sequence, and the material cooled by the cooler and the material flowing out of the liquid phase outlet of the condenser are both transported to alkali washing, water washing, drying, purification and refining processes. The electrolytic cell body can adopt a traditional fluorination substitution reaction electrolytic cell, such as the traditional electrolytic cell used for the production of perfluoroacyl fluoride compounds and perfluorosulfonyl fluoride compounds, or various new electrolytic fluorination substitution reaction process equipment. While the electrolytic fluorination substitution reaction is in progress, hydrogen chloride and hydrogen are generated at the negative electrode of the electrolytic cell, which are removed from the tail gas treatment through the gas phase outlet of the condenser, and are harmlessly treated by the tail gas absorption and separation device before being vented.

[0029] The beneficial effects of the present invention are:

[0030] 1. The raw materials of the present invention are cheap and readily available, and the source is convenient;

[0031] 2. The synthesis process of the present invention is safe and suitable for industrial production;

[0032] 3. The preparation method of the present invention is simple and the process is mature. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0034] Figure 1 It is a flow chart of the electrolysis process of the present invention.

[0035] The markings in the figure are: 1. electrolytic cell; 2. feed port; 3. first outlet; 4. second outlet; 5. condenser; 6. sight glass; 7. cooler. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0037] The electrolytic fluorination substitution reaction process used in the following examples and comparative examples can be seen in the process flow Figure 1 The preparation device includes an electrolytic cell, the electrolytic cell is provided with a cooling jacket, the top of the electrolytic cell is provided with a feed port and a first outlet, the bottom of the electrolytic cell is provided with a second outlet, the first outlet is connected to a condenser, and the second outlet is connected to a sight glass and a cooler in sequence. The material cooled by the cooler and the material flowing out of the liquid phase outlet of the condenser are both transported to the alkali washing, water washing and drying processes.

[0038] Specifically, the electrolytic cell has a capacity of 1000 ml, with the positive and negative electrodes configured as single-electrode pairs and connected to a power supply capable of providing continuous DC voltage. The surface area of ​​each electrode is 120 square millimeters, with a 50-mm interelectrode spacing. The positive electrode is made of nickel plate (N8), while the negative electrode is made of iron plate (Fe). The cooler, condenser, valves, and piping are all made of materials resistant to hydrogen fluoride corrosion. The cooling system utilizes a conventional laboratory refrigeration cycle unit, and the cooling medium is a 50% ethylene glycol aqueous solution.

[0039] The mass percentage of the feed materials in the following examples and comparative examples refers to the percentage of the mass of the raw material 1,3-butadiene and / or 1,3-chlorobutadiene to the total mass of the raw material and the mass of anhydrous hydrogen fluoride.

[0040] Example 1

[0041] 60 g of 1,3-butadiene and 690 g of anhydrous hydrogen fluoride (8% by mass) were added to an electrolytic cell. The temperature of the mixed liquid in the electrolytic cell was controlled at -8°C and the DC voltage was controlled at 4.2 V to carry out an electrolytic fluorination substitution reaction. After 24 hours, most of the perfluorinated phase electrolyte was separated through a sight glass and a valve connected to the second outlet of the electrolytic cell. After being combined with a small amount of electrolyte from the liquid phase outlet of the gas phase condenser connected to the first outlet of the electrolytic cell, the electrolyte was alkali washed, water washed, and dried to obtain the product hexafluoro-1,3-butadiene. The operating conditions and product yields are listed in Table 1.

[0042] The detection of hexafluoro-1,3-butadiene shall be carried out in accordance with the method specified in the national standard GB / T 41326-2022.

[0043] Hexafluoro-1,3-butadiene NMR fluorine spectrum data: 19 FNMR (CDCl3, 367Hz): -90.44 (dd, J1=24Hz, J2=42Hz, 2F), -104.28 (dd, J1=48Hz, J2=103Hz, 2F), -179.23 (dd, J1=J2=24Hz, 2F).

[0044] Example 2

[0045] The controlled temperature of the mixed liquid in the electrolytic cell in Example 1 was adjusted to -4°C, the continuous DC voltage was adjusted to 6V, and other conditions remained unchanged. The results are shown in Table 1.

[0046] Example 3

[0047] The raw material 1,3-butadiene in Example 1 was changed to 1-chloro-1,3-butadiene, and its specific mass and the corresponding feed mass percentage (8%) remained unchanged. Other conditions remained unchanged. The results are shown in Table 1.

[0048] Example 4

[0049] The raw material in Example 1 was changed to hexachloro-1,3-butadiene, and other conditions remained unchanged. The results are shown in Table 1.

[0050] Comparative Example 5

[0051] The continuous DC voltage in Example 4 was adjusted to 11 V, and the corresponding feed mass percentage of the raw material hexachloro-1,3-butadiene was changed to 10% (the total feed amount remained unchanged at 750 g, except that the feed amount of hexachloro-1,3-butadiene was increased to 75 g, and the corresponding mass of anhydrous hydrogen fluoride was reduced). Other conditions remained unchanged. The results are shown in Table 1.

[0052] Comparative Example 6

[0053] The temperature of the mixed liquid in the electrolytic cell in Example 4 was adjusted to 15° C. At this time, most of the crude product was collected through the liquid phase outlet of the condenser connected to the second outlet of the electrolytic cell. Other conditions remained unchanged. The results are shown in Table 1.

[0054] Comparative Example 7

[0055] The positive electrode material of the electrolytic cell used in Example 4 was replaced by a carbon-based electrode material from a metal nickel plate (N8). Other operating conditions were the same as in Example 4. The results are shown in Table 1.

[0056] Table 1: Main parameters and product yields of each embodiment

[0057]

[0058] Through the operation of the examples, the optimized conditions of the present invention are: the positive electrode material of the electrolytic cell is a metal nickel plate (N8), and the negative electrode is a metal iron plate; the raw materials are hexachloro-1,3-butadiene and anhydrous hydrogen fluoride, and the weight percentage of the raw materials is 8%; the continuous DC voltage is preferably 4.2V; and the temperature of the mixed liquid in the electrolytic cell is controlled to -8°C.

[0059] It should be understood that the above-described specific embodiments of the present invention are merely illustrative or illustrative of the principles of the present invention and do not constitute limitations of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included within the scope of protection of the present invention. In addition, the appended claims are intended to cover all variations and modifications that fall within the scope and metes and bounds of the appended claims, or equivalents thereof.

Claims

1. A method for preparing hexafluoro-1,3-butadiene, characterized in that: The raw materials 1,3-butadiene and / or 1,3-chlorobutadiene are mixed with anhydrous hydrogen fluoride in a certain proportion and put into an electrolytic cell. The mixed liquid to be electrolyzed contacts the positive and negative electrodes of the electrolytic cell. Under the conditions of a DC voltage of 2-10V between the positive and negative electrodes and a temperature of the mixed liquid in the electrolytic cell of -10°C to -4°C, an electrolytic fluorination substitution reaction is carried out. The positive electrode material used in the electrolytic cell is metallic nickel; the negative electrode material is one of metallic nickel and metallic iron.

2. The preparation method according to claim 1, characterized in that The mass of the raw material 1,3-butadiene and / or chloro-1,3-butadiene accounts for 1-10% of the total mass of the raw material and the mass of anhydrous hydrogen fluoride.

3. The preparation method according to claim 1, characterized in that The electrolytic fluorination reaction takes 12-24 hours.

4. The preparation method according to claim 1, characterized in that The DC voltage of the positive and negative electrodes of the electrolytic cell is 2-8 V.

5. The preparation method according to claim 1, characterized in that The gaseous product flowing out from the first outlet at the top of the electrolytic cell is condensed and collected, and at the same time, the liquid product flowing out from the second outlet at the bottom of the electrolytic cell is cooled and collected to obtain a crude hexafluoro-1,3-butadiene product; wherein, most of the crude hexafluoro-1,3-butadiene product is obtained by cooling and collecting the liquid product.

6. The preparation method according to claim 5, characterized in that The purification and refining process of the crude hexafluoro-1,3-butadiene comprises the following steps: firstly, the crude hexafluoro-1,3-butadiene is alkali washed and water washed, and then the alkali washed and water washed product is dried.

7. The preparation method according to claim 1, characterized in that The positive and negative electrodes are in the form of a single electrode pair or a multi-electrode pair in which the positive and negative electrodes are arranged at intervals.

8. The preparation method according to claim 1, characterized in that The positive and negative electrodes of the electrolytic cell are connected to a power supply device capable of providing a DC voltage.

9. The preparation method according to claim 1, characterized in that The electrolytic cell is provided with a cooling jacket, a cooling coil or a liquid phase cooling circulation system with a heat exchanger for controlling the temperature of the liquid in the electrolytic cell.

10. The preparation method according to claim 6, characterized in that The first outlet is connected to a gas phase condenser, and the gas phase condenser is provided with a gas phase tail gas outlet and a liquid phase outlet; The second outlet is connected to the sight glass and the liquid phase cooler in sequence. The material cooled by the liquid phase cooler and the material at the liquid phase outlet of the gas phase condenser are both transported to the alkali washing, water washing, drying and purification process.

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