Preparation method of bis (trifluoromethyl) sulfide

Abstract

The invention discloses a preparation method of bis (trifluoromethyl) sulfide. The preparation method disclosed by the invention comprises the following steps: reacting cracked gas with trifluoromethylthio salt in an organic solvent at 0-50 DEG C in the presence of a composite catalyst and protonic acid, cooling reaction gas generated in the reaction process after the reaction gas passes through a condensation pipe, and recovering a product, the pyrolysis gas is gas generated by reacting tetrafluoroethylene and sulfur at the reaction temperature of 400-600 DEG C; the invention provides a preparation method of safe and nontoxic bis (trifluoromethyl) sulfide.

Description

Technical Field

[0001] The invention relates to a method for preparing a novel insulating gas, in particular to a method for preparing bis(trifluoromethyl) sulfide. Background Art

[0002] Bis(trifluoromethyl)sulfide (CF3SCF3) is a new type of insulating gas with a dielectric strength 1.5 times that of SF6, a liquefaction temperature of -22°C, and low toxicity (LC 50 >20000ppm), GWP is 3, and thermal stability is good. It is a new type of insulating gas whose comprehensive performance meets the requirements of power grid use. Prior art CN202410537079.5 and CN20241537083.1 disclose the preparation method of CF3SCF3. However, both methods use the highly toxic intermediate CF3SSCF3, which is extremely biologically hazardous. Summary of the invention

[0003] In view of the shortcomings and defects of the prior art, the present invention provides a method for preparing bistrifluoromethyl sulfide.

[0004] To this end, the preparation method of bis(trifluoromethyl) sulfide provided by the present invention comprises the following steps:

[0005] The cracked gas reacts with trifluoromethylthio salt in an organic solvent at 0 to 50° C. and in the presence of a composite catalyst and a protonic acid, and the reaction gas generated during the reaction passes through a condenser and is cooled to recover the product; the temperature of the condenser is -30 to 10° C., and the cooling temperature is lower than the temperature of the condenser;

[0006] The cracking gas is a gas produced by cracking tetrafluoroethylene and sulfur at a reaction temperature of 400 to 600°C.

[0007] The composite catalyst is a mixture of crown ether and alkali metal bromide.

[0008] Alternatively, the cooling recovery is performed in a dry ice bath.

[0009] An optional solution is that the crown ether is 18-crown-6 ether, 15-crown-5 ether, benzo-18-crown-6 ether or dibenzo-18-crown-6 ether; and the alkali metal bromide is KBr, NaBr, KBr or KBr.

[0010] An optional solution is that the composite catalyst is a mixture of 18-crown-6 ether and KBr, a mixture of 15-crown-5 ether and NaBr, a mixture of benzo-18-crown-6 ether and KBr, or a mixture of dibenzo-18-crown-6 ether and KBr.

[0011] Alternatively, the protonic acid is tetrafluoroboric acid, hexafluorophosphoric acid, trifluoroacetic acid or pentafluoroantimonic acid.

[0012] Alternatively, the trifluoromethylthio salt is trifluoromethylthiotetramethylammonium, trifluoromethylthio(2,2'-bipyridine)copper or trifluoromethylthiosilver.

[0013] Alternatively, the organic solvent is tetrahydrofuran, ethylene glycol dimethyl ether, dimethylformamide, dimethylacetamide or dimethylthioformamide.

[0014] An optional solution is that the method for preparing the cracking gas comprises: in a fixed bed reactor, heating sulfur to 400-600° C., and then introducing tetrafluoroethylene gas to react with the gas to produce cracking gas.

[0015] An optional solution is that the reaction time of the cracking gas and the trifluoromethylsulfanyl salt is 1 hour to 5 hours.

[0016] An optional solution is that the mass ratio of the composite catalyst to trifluoromethyl sulfide is 0.1 to 0.8:1.

[0017] The synthesis method of the invention has the advantages of safe reaction, high efficiency and high reaction selectivity, and the yield of bistrifluoromethyl sulfide can reach more than 90% under relatively optimal conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The gas chromatography analysis results of the product prepared in Example 1 are shown in FIG. DETAILED DESCRIPTION

[0019] Unless otherwise specified, the scientific and technical terms in the present invention are understood according to the knowledge of ordinary technicians in the relevant fields.

[0020] It should also be understood that the temperatures and concentrations referred to herein are approximate values ​​for illustrative purposes. Although methods and materials similar to or equivalent to the methods and materials described herein can be used for the implementation of the present disclosure, some suitable methods and materials are described below. The publications, patent applications, patents and other references mentioned herein are partially incorporated herein by reference, and if there is a conflict, this article shall prevail.

[0021] The present invention prepares difluorocarbon sulfide in situ by reacting tetrafluoroethylene with sulfur, and then reacts with trifluoromethylthio salt to prepare bistrifluoromethyl sulfide. The specific reaction equation is:

[0022]

[0023] The present invention is further described in detail below with reference to the examples, but the scope of the present invention is not limited thereto. The materials, methods, solution concentrations and embodiments described in the following examples are exemplary only and are not intended to be limiting. In the specific scheme, those skilled in the art can optimize the values ​​of the operating parameters such as the specific substances, material ratios, concentrations, temperatures, reaction times, etc. involved in the method according to the disclosure of the present invention by conventional experimental methods to achieve the purpose of the present invention.

[0024] The catalyst used in the present invention can be a corresponding commercial product, or can be prepared by a synthesis method including but not limited to those known to those skilled in the art.

[0025] The products in the following examples were detected by gas chromatography, and the chromatographic conditions were as follows: vaporization chamber 200°C, detector 200°C, chromatographic column selected gaspro column with specifications of 30m×0.25mm, column temperature initially 50°C, constant temperature for 5 minutes, program heating to 200°C at 15°C / min, and constant temperature for 10 minutes.

[0026] Embodiment 1:

[0027] Preparation of cracking gas used in this embodiment:

[0028] Sulfur (300 g) was gradually heated to 450°C in a fixed bed reactor at a heating rate of 10°C / min, and tetrafluoroethylene (1000 g) gas was introduced, and the cracked gas produced by the reaction was reserved for use;

[0029] Preparation of bis(trifluoromethyl)sulfide:

[0030] In a kettle reactor, trifluoromethylthiotetramethylammonium (175 g), potassium bromide (120 g), dibenzo-18-crown 6 ether (10 g), hexafluorophosphoric acid (5 g) and dimethylformamide (200 mL) were added in sequence, and mechanical stirring was started at a stirring speed of 800 r / min. The reaction temperature was maintained at 25°C. After 10 minutes, the prepared cracking gas was introduced, the condenser was cooled to -5°C, and the gas at the top of the condenser was collected in a dry ice bath. After reacting for 3 hours, samples were taken and analyzed by gas chromatography (the results are shown in FIG. Figure 1 As shown), bistrifluoromethyl sulfide (258 g) was obtained with a yield of 93%.

[0031] Embodiment 2:

[0032] Preparation of cracking gas used in this embodiment:

[0033] Sulfur (25 g) was gradually heated to 500° C. at a heating rate of 8° C. / min in a fixed bed reactor, and tetrafluoroethylene (100 g) gas was introduced to react and prepare cracking gas for standby use;

[0034] Preparation of bis(trifluoromethyl)sulfide:

[0035] In a kettle reactor, trifluoromethylthio (2,2'-bipyridine) copper (10 g), sodium bromide (3.2 g), 15 crown 5 ether (0.5 g), tetrafluoroboric acid (0.1 g) and anhydrous tetrahydrofuran (50 mL) were added in sequence, and mechanical stirring was started at a stirring speed of 800 r / min. The reaction temperature was maintained at 40°C. After 10 minutes, the prepared cracking gas was introduced, the condenser was cooled to 5°C, and the gas on the top of the condenser was collected in a dry ice bath. After reacting for 2 hours, the temperature was lowered and sampling was performed. After gas chromatography analysis, bistrifluoromethyl sulfide (5 g) was obtained with a yield of 91%.

[0036] Embodiment 3:

[0037] Preparation of cracking gas used in this embodiment:

[0038] Sulfur (20 g) was gradually heated to 550° C. at a heating rate of 8° C. / min in a fixed bed reactor, and tetrafluoroethylene (60 g) gas was introduced to prepare cracking gas for use;

[0039] Preparation of bis(trifluoromethyl)sulfide:

[0040] In a kettle reactor, silver trifluoromethylthioate (2.1 g), potassium bromide (1.5 g), benzo-18-crown-6 ether (0.01 g), pentafluoroantimonic acid (0.001 g) and dimethylthioformamide (5 mL) were added in sequence, and mechanical stirring was turned on at a stirring speed of 800 r / min. The reaction temperature was maintained at 30° C. After 10 minutes, the prepared cracking gas was introduced, the condenser was cooled to 5° C., and the gas at the top of the condenser was collected in a dry ice bath. After reacting for 2 h, the temperature was lowered and sampling was performed. After gas chromatography analysis, bistrifluoromethyl sulfide (1.6 g) was obtained with a yield of 94%.

[0041] Embodiment 4~8:

[0042] The difference between Examples 4 to 8 and Example 1 is that the organic solvent in the preparation step of bistrifluoromethyl sulfide is changed, and the reaction temperature and reaction time are adjusted. The reaction results are shown in Table 1.

[0043] Comparative Examples 1-3:

[0044] Different from Example 1, the preparation step of bistrifluoromethyl sulfide in Comparative Example 1 is carried out in the absence of an organic solvent; the preparation step of bistrifluoromethyl sulfide in Comparative Example 2 is carried out in the absence of an organic solvent and a composite catalyst; and the preparation step of bistrifluoromethyl sulfide in Comparative Example 3 is carried out in the absence of a composite catalyst.

[0045] The specific results are shown in Table 1.

[0046] Table 1

[0047]

[0048]

[0049] The above descriptions are only some embodiments of the present invention and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A method for preparing bis(trifluoromethyl) sulfide, characterized in that: include: The cracked gas reacts with trifluoromethylthio salt in an organic solvent at 0 to 50° C. and in the presence of a composite catalyst and a protonic acid, and the reaction gas generated during the reaction passes through a condenser and is cooled to recover the product; the temperature of the condenser is -30 to 10° C., and the cooling temperature is lower than the temperature of the condenser; The cracking gas is a gas produced by cracking tetrafluoroethylene and sulfur at a reaction temperature of 400 to 600°C. The composite catalyst is a mixture of crown ether and alkali metal bromide.

2. The method for preparing bis(trifluoromethyl) sulfide according to claim 1, characterized in that: The cooling recovery is carried out in a dry ice bath.

3. The method for preparing bis(trifluoromethyl) sulfide according to claim 1, characterized in that: The crown ether is 18-crown-6 ether, 15-crown-5 ether, benzo-18-crown-6 ether or dibenzo-18-crown-6 ether; and the alkali metal bromide is KBr, NaBr, KBr or KBr.

4. The method for preparing bis(trifluoromethyl) sulfide according to claim 1, characterized in that: The composite catalyst is a mixture of 18-crown-6 ether and KBr, a mixture of 15-crown-5 ether and NaBr, a mixture of benzo-18-crown-6 ether and KBr, or a mixture of dibenzo-18-crown-6 ether and KBr.

5. The method for preparing bis(trifluoromethyl) sulfide according to claim 1, characterized in that: The protonic acid is tetrafluoroboric acid, hexafluorophosphoric acid, trifluoroacetic acid or pentafluoroantimonic acid.

6. The method for preparing bis(trifluoromethyl) sulfide according to claim 1, characterized in that: The trifluoromethylthio salt is trifluoromethylthio tetramethylammonium, trifluoromethylthio (2,2'-bipyridine) copper or trifluoromethylthio silver.

7. The method for preparing bis(trifluoromethyl) sulfide according to claim 1, characterized in that: The organic solvent is tetrahydrofuran, ethylene glycol dimethyl ether, dimethylformamide, dimethylacetamide or dimethylthioformamide.

8. The method for synthesizing bis(trifluoromethyl) sulfide according to claim 1, characterized in that: The method for preparing cracked gas comprises: in a fixed bed reactor, heating sulfur to 400-600° C., and then introducing tetrafluoroethylene gas to react with the gas to generate cracked gas.

9. The method for synthesizing bis(trifluoromethyl) sulfide according to claim 1, characterized in that: The reaction time of the cracking gas and the trifluoromethylsulfonyl salt is 1 h to 5 h.

10. The method for synthesizing bis(trifluoromethyl) sulfide according to claim 1, characterized in that: The mass ratio of the composite catalyst to trifluoromethyl sulfide is 0.1-0.8:1.

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