A method for preparing 1,1,1,4,4,4-hexafluorobutane

Abstract

The invention discloses a method for preparing 1,1,1,4,4,4-hexafluorobutane, and belongs to the technical field of fluorine-containing fine chemicals. The method for preparing 1,1,1,4,4,4-hexafluorobutane of the present invention uses 3-chloro-1,1,1-trifluoropropane as a substrate, and reacts with trifluoromethane in a reaction solvent under the conditions of cuprous halide and tert-butanol alkali metal salt to generate 1,1,1,4,4,4-hexafluorobutane. The 3-chloro-1,1,1-trifluoropropane utilized is a by-product produced in the industrial production of 3,3,3-trifluoropropylene, and the raw material source is widely cheap and easy to obtain. In the presence of cuprous halide and tert-butanol alkali metal salt, 1,1,1,4,4,4-hexafluorobutane is prepared by a next step method, and the raw material conversion rate is high, the product selectivity is high, and the yield is higher than 83%. The reaction process is short and controllable, and the reaction conditions are mild, which avoids the safety problems caused by the use of hydrogen in the existing 1,1,1,4,4,4-hexafluorobutane preparation method.

Description

Technical Field

[0001] The invention discloses a method for preparing 1,1,1,4,4,4-hexafluorobutane, and belongs to the technical field of fluorine-containing fine chemicals. Background Art

[0002] 1,1,1,4,4,4-hexafluorobutane (1,1,1,4,4,4-hexafluorobutane), also known as HFC-356, molecular formula C4H4F6, molecular weight 166.06, density 1.37g / cm 3 , boiling point 24-25ºC, melting point -53ºC. HFC-356 has a boiling point very close to that of CFC-11, and has an acceptable low-temperature condensation effect in foam bubbles. It can be processed and applied using ordinary processing technology, without the need for special foam processing equipment. This is because HFC-356 has no flash point and will not form an explosive mixture with air. In addition, 1,1,1,4,4.4-hexafluorobutane is less corrosive to commonly used lining materials than CFC-11. This property can enable equipment manufacturers to stop using expensive materials and methods. Therefore, HFC-356 has the potential to replace HCFC-141b as a blowing agent in the foam material formulation of equipment, and has broad application prospects.

[0003] The production of 1,1,1,4,4,4-hexafluorobutane in the prior art has the problem of harsh preparation conditions and easy explosion. For example, US Pat. No. 5,510,545A reports the preparation of 1,1,1,4,4,4-hexafluorobutane with R113a. A Ni / SiO2 catalyst is filled in a reaction tube, R113a and hydrogen are introduced, heated, the product is washed, dried on a molecular sieve and condensed to obtain a mixture. According to qualitative analysis by gas chromatography, 96% of the product is HFC-356, 1.85% is R113a, 0.9% is 1-chloro-2,2,2-trifluoroethane, and 0.5% is halogenated products with less content such as 1,1,1-trifluoroethane. US Pat. No. 5,523,497A reports the thermal decomposition reaction of 1,1,1-trifluoro-2,2-dichloroethane to obtain a method for hexafluorochlorobutene. The hexafluorochlorobutene obtained in this way can be used to generate hexafluorobutane through a hydrogenation reaction. U.S. Patent No. 5,672,787A reports a method for preparing 1,1,1,4,4,4-hexafluorobutane in a liquid phase. When 1,1,1,4,4,4-hexafluorobutene reacts with hydrogen in a liquid phase in the presence of a noble metal catalyst, it has excellent selectivity and a yield of 99%.

[0004] All of the above methods use hydrogen, which has the following disadvantages: the reaction materials are explosive and flammable, and the explosion limit of hydrogen is 4% to 75%, which has a high explosion hazard characteristic; hydrogenation is a strong exothermic reaction, and hydrogen comes into contact with steel under high temperature and high pressure. The carbon molecules in the steel are easily reacted with hydrogen to form hydrocarbons, which reduces the strength of steel equipment and causes hydrogen embrittlement; explosions are easily caused during the regeneration and activation of the catalyst; incompletely reacted hydrogen and other impurities in the exhaust gas of the hydrogenation reaction are easy to cause fire or explosion when discharged.

[0005] Therefore, it is urgent to develop a method for preparing 1,1,1,4,4,4-hexafluorobutane that can overcome the problems of harsh reaction conditions, easy explosion and potential safety hazards in the prior art 1,1,1,4,4,4-hexafluorobutane preparation method, which has mild reaction conditions and high safety. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing 1,1,1,4,4,4-hexafluorobutane by using 3-chloro-1,1,1-trifluoropropane and trifluoromethane as main raw materials, in view of the problems that the prior art method for preparing 1,1,1,4,4,4-hexafluorobutane has harsh conditions, is prone to explosion and has potential safety hazards. The method has mild reaction conditions and is a method for preparing 1,1,1,4,4,4-hexafluorobutane with high safety.

[0007] In order to achieve the purpose of the invention, the technical solution adopted by the present invention is:

[0008] A method for preparing 1,1,1,4,4,4-hexafluorobutane, using 3-chloro-1,1,1-trifluoropropane as a substrate, reacting with trifluoromethane (R23) in a reaction solvent in the presence of cuprous halide and tert-butoxide alkali metal salt to generate 1,1,1,4,4,4-hexafluorobutane. The synthesis route is as follows:

[0009] .

[0010] Preferably, the molar ratio of the alkali metal salt of tert-butoxide to trifluoromethane to 3-chloro-1,1,1-trifluoropropane is 1:1:3-5.

[0011] Preferably, the cuprous halide is cuprous chloride.

[0012] Preferably, the alkali metal salt of tert-butoxide is any one of sodium tert-butoxide and potassium tert-butoxide.

[0013] Preferably, the reaction solvent is any one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

[0014] Preferably, the molar ratio of the cuprous halide, the alkali metal salt of tert-butoxide, and the reaction solvent is 1:1-5:5-25.

[0015] Preferably, the reaction time of the reaction is 12 to 20 hours.

[0016] Preferably, the reaction pressure of the reaction is 0 to 2.0 MPa.

[0017] Preferably, the reaction temperature of the reaction is 100-220°C.

[0018] Preferably, the reaction uses a high-pressure reactor as a reaction vessel.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The method for preparing 1,1,1,4,4,4-hexafluorobutane of the present invention uses 3-chloro-1,1,1-trifluoropropane, which is a by-product produced in the industrial production of 3,3,3-trifluoropropene. The raw material source is wide, cheap and easy to obtain.

[0021] 2. The method for preparing 1,1,1,4,4,4-hexafluorobutane of the present invention is to prepare 1,1,1,4,4,4-hexafluorobutane in the presence of cuprous halide and alkali metal salt of tert-butoxide in a one-step process, with high raw material conversion rate, high product selectivity and a yield higher than 83%.

[0022] 3. The method for preparing hexafluorobutane of the present invention has a short and controllable reaction process and mild reaction conditions, which effectively avoids a series of safety problems caused by the use of hydrogen in the existing method for preparing 1,1,1,4,4,4-hexafluorobutane. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the examples, which are used to illustrate the present invention but are not intended to limit the scope of protection of the present invention. The conditions in the examples can be further adjusted according to specific conditions, and simple improvements to the method of the present invention under the premise of the concept of the present invention all belong to the scope of protection claimed in the present invention.

[0024] Example 1

[0025] Add cuprous chloride (9.9 g, 0.1 mol), potassium tert-butoxide (56.1 g, 0.5 mol), N, N-dimethylformamide (36.6 g, 0.5 mol) to a 1L stainless steel stirring autoclave, stir at room temperature for 0.5 h, add 3-chloro-1,1,1-trifluoropropane (197.8 g, 1.5 mol), and then charge trifluoromethane (35.0 g, 0.5 mol) into the above reaction solution, slowly heat to 140 ° C, react for 14 h, cool to room temperature, rectify, collect 21-23 ° C fractions, and obtain 1,1,1,4,4,4-hexafluorobutane product. Take trifluoromethane as the substrate and calculate the yield.

[0026] Example 2

[0027] Cuprous chloride (9.9 g, 0.1 mol), sodium tert-butoxide (48.05 g, 0.5 mol), N, N-dimethylformamide (36.6 g, 0.5 mol) were added to a 1L stainless steel stirred autoclave, stirred at room temperature for 0.5 h, 3-chloro-1,1,1-trifluoropropane (329.6 g, 2.5 mol) was added, and trifluoromethane (35.0 g, 0.5 mol) was charged into the above reaction solution, slowly heated to 140°C, reacted for 14 h, cooled to room temperature, distilled, and collected the 21-23°C fraction to obtain the finished product of 1,1,1,4,4,4-hexafluorobutane. With trifluoromethane as the substrate, the yield was statistically calculated and the yield was 90.5%.

[0028] Embodiments 3 to 5

[0029] The difference between Examples 3 to 5 and Example 1 is that the solvent is changed, and the reaction parameters and reaction results are shown in Table 1.

[0030] Table 1 Reaction parameters and results of Examples 3 to 5

[0031] Solvents Yield, % Example 1 N,N-Dimethylformamide 91.5 Example 3 N,N-Dimethylacetamide 90.7 Example 4 N-Methylpyrrolidone 91.4 Example 5 Dimethyl sulfoxide 87.6

[0032] Embodiment 6-7

[0033] The difference between Examples 6 and 7 and Example 1 is that the molar ratio of trifluoromethane to 3-chloro-1,1,1-trifluoropropane has an effect on the reaction results as shown in Table 2.

[0034] Table 2 Reaction parameters and results of Examples 6 to 7

[0035] Molar ratio of trifluoromethane to 3-chloro-1,1,1-trifluoropropane Yield, % Example 1 1:3 91.5 Example 6 1:4 92.1 Example 7 1:5 90.7

[0036] Embodiments 8 to 10

[0037] The difference between Examples 8 to 10 and Example 1 is that the amount of solvent has an effect on the reaction results as shown in Table 3.

[0038] Table 3 Reaction parameters and results of Examples 8 to 10

[0039] N,N-dimethylformamide solvent amount / mol Yield, % Example 1 0.5 91.5 Example 8 0.7 90.6 Example 9 0.9 88.4 Example 10 1.0 88.2

[0040] Examples 11-12

[0041] The difference between Examples 11 to 12 and Example 1 is that the reaction time has an effect on the reaction results as shown in Table 4.

[0042] Table 4 Reaction parameters and results of Examples 11 to 12

[0043] Reaction time Yield, % Example 1 12 91.5 Embodiment 11 16 91.8 Example 12 20 90.9

[0044] Embodiments 13 to 15

[0045] The difference between Examples 13 to 15 and Example 1 is that the reaction temperature has an effect on the reaction results as shown in Table 5.

[0046] Table 5 Reaction parameters and results of Examples 13 to 15

[0047] Reaction temperature / ℃ Yield, % Example 1 100 91.5 Example 13 140 90.2 Embodiment 14 180 85.4 Embodiment 15 220 83.6

[0048] In summary, through the specific implementation data of the above embodiments, the method for preparing 1,1,1,4,4,4-hexafluorobutane of the present invention has mild reaction conditions, a yield higher than 83%, and high product selectivity.

[0049] The preferred embodiments of the present disclosure are described in detail above, but the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, the technical solution of the present disclosure can be subjected to a variety of simple modifications, and these simple modifications all belong to the protection scope of the present disclosure. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations. In addition, the various different embodiments of the present disclosure can also be arbitrarily combined, as long as they do not violate the ideas of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for preparing 1,1,1,4,4,4-hexafluorobutane, characterized in that: 3-Chloro-1,1,1-trifluoropropane is used as a substrate, and in the presence of cuprous halide and tert-butoxide alkali metal salt, it reacts with trifluoromethane in a reaction solvent to generate 1,1,1,4,4,4-hexafluorobutane. The synthesis route is as follows: ， Where X is Cl, M is Na or K; The molar ratio of the alkali metal salt of tert-butoxide to trifluoromethane to 3-chloro-1,1,1-trifluoropropane is 1:1:3-5; The cuprous halide is cuprous chloride; The alkali metal salt of tert-butoxide is any one of sodium tert-butoxide and potassium tert-butoxide; The molar ratio of the cuprous halide, tert-butoxide alkali metal salt and reaction solvent is 1: 5: 5-10; The reaction temperature of the reaction is 100-220°C; The reaction time of the reaction is 12 to 20 hours.

2. A method for preparing 1,1,1,4,4,4-hexafluorobutane as claimed in claim 1, characterized in that: The reaction solvent is any one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

3. A method for preparing 1,1,1,4,4,4-hexafluorobutane as claimed in claim 1, characterized in that: To a 1L stainless steel stirred autoclave, add 9.9g of cuprous chloride, 56.1g of potassium tert-butoxide, and 36.6g of N,N-dimethylformamide, and stir at room temperature for 0.5h. Add 197.8g of 3-chloro-1,1,1-trifluoropropane, and then charge 35.0g of trifluoromethane into the above reaction solution. Slowly heat to 140°C, react for 14h, cool to room temperature, and distill. Collect the 21-23°C fraction to obtain 1,1,1,4,4,4-hexafluorobutane.

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