Preparation method of 3, 3-dichloro-1, 1, 2-trifluoropropane

Abstract

The invention discloses a preparation method of 3, 3-dichloro-1, 1, 2-trifluoropropane, and the preparation method comprises the following steps: 1, 2-difluoroethylene and dichlorofluoromethane are subjected to a one-step telomerization reaction under the combined action of a prefluorinated telomerization catalyst, an accelerant and a polar aprotic solvent to obtain 3, 3-dichloro-1, 1, 2-trifluoropropane, and the 3, 3-dichloro-1, 1, 2-trifluoropropane is subjected to a one-step telomerization reaction to obtain 3, 3-dichloro-1, 1, 2-trifluoropropane. The catalyst is a halogenated alkane pre-fluorinated Lewis acid catalyst, the accelerant is at least one of trichloromethane, difluorochloromethane and fluorochloromethane, and the polar aprotic solvent is at least one of N, N-dimethylformamide, N, N-dimethylacetamide, acetonitrile, dimethyl sulfoxide and N-methyl pyrrolidone. Chlorofluorocarbon carbon chain growth is realized through one-step telomerization, a target product is obtained, and the method has the advantages of being simple in process, low in cost, high in product selectivity, suitable for industrial application and the like.

Description

Technical Field

[0001] The present invention relates to a method for preparing chlorofluoropropane, and particularly to a method for obtaining 3,3-dichloro-1,1,2-trifluoropropane through a telomerization reaction by using 1,2-difluoroethylene and dichlorofluoromethane as raw materials under the combined action of a catalyst, a promoter and a solvent. Background Art

[0002] 1,1,2-Trifluoroethane (HFC-143) is a by-product of the hydrogenation and dechlorination of chlorotrifluoroethylene (CTFE) to prepare trifluoroethylene (TrFE). Currently, it is mostly burned in the fluorochemical industry chain. There are also studies on the resource utilization of HFC-143. For example, as proposed in Patent CN112088150A, HFC-143 by-product can be converted into 1,2-difluoroethylene (HFO-1132). The conversion rate of HFC-143 after 1 hour of reaction and the selectivity of HFO-1132 can reach 89% and 90% respectively. However, the Cr-based catalyst used in the reaction has high biological toxicity, and the conversion rate of the catalyst drops rapidly to 52% after 10 hours of reaction. It is necessary to delay carbon deposition deactivation through an oxygen atmosphere, but it may bring other by-products. In order to further highlight the use value of this by-product, improve the stability of the catalyst, extend the value chain of by-product utilization, and realize the co-production of multiple new environmentally friendly fluorinated olefin refrigerants, it is still necessary to further broaden its application scenarios.

[0003] 3,3-Dichloro-1,1,2-trifluoropropane, abbreviated as HCFC-243eb, has a density of 1.411±0.06 g / cm 3 , a boiling point of 30.2 °C (experimental value). The unique difluoromethyl group on its molecule can be used as a hydrogen bond donor and can be used as a lipophilic electron isostere for amides, alcohols, thiols and hydroxamic acids in drug design. It can also obtain the fourth-generation new low-GWP refrigerant HCFO-1233yd through dehydrochlorination reaction and an important chlorofluorinated olefin intermediate through defluorination reaction. However, there are very few research reports on the synthesis of 3,3-dichloro-1,1,2-trifluoropropane. The main routes are as follows:

[0004] (1) Patent WO2022138675A1 discloses that 3,3-dichloro-1,1,2-trifluoropropane can be prepared by dehydrochlorination process to obtain HCFO-1233yd containing cis-trans isomers, but does not mention the preparation method of this raw material. And this raw material belongs to the category of HCFCs and cannot be directly purchased. It needs to be prepared through multiple processes from upstream raw materials.

[0005] Therefore, from the perspective of industrialization, the starting raw materials of the above-mentioned preparation process route of 3,3-dichloro-1,1,2-trifluoropropane are not easily obtained, and it does not have the operability and economy for large-scale production. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a preparation method of 3,3-dichloro-1,1,2-trifluoropropane, which has the advantages of easily available raw materials, low cost, simple process, high product selectivity, and is particularly suitable for industrial production.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] A preparation method of 3,3-dichloro-1,1,2-trifluoropropane, the preparation method comprising: under the combined action of a telomerization catalyst, a promoter and a polar aprotic solvent, 1,2-difluoroethylene (HFO-1132) and dichlorofluoromethane (HFO-113) are subjected to a one-step telomerization reaction to obtain 3,3-dichloro-1,1,2-trifluoropropane, and the reaction equation is as follows:

[0009]

[0010] Traditional inorganic chloride telomerization catalysts are prone to deliquescence, and toxic HCl gas is decomposed by moisture absorption during the reaction process. This not only causes relatively serious corrosion to the reaction equipment, but also causes great physical damage to experimental operators, and the reaction needs to be carried out in a homogeneous phase.

[0011] The present invention has developed a supported telomerization catalyst. The carrier is selected from coal-based activated carbon pretreated with acid and alkali, and the telomerization catalyst is selected from at least one of AlCl3 / AC, GaCl3 / AC, ZrCl4 / AC, and SnCl4 / AC; the loading amount of the active component of the telomerization catalyst is 5-20% (the loading amount is calculated based on the mass of metal chloride relative to the mass of activated carbon); the telomerization catalyst needs to be pre-fluorinated with at least one halogenated alkane such as difluorochloromethane, chlorofluoromethane, and trifluoromethane at 200-300 °C for 2-3 h before the reaction, so as to form relatively rich Lewis acid sites on the catalyst surface and improve the reaction activity of the telomerization catalyst. When the reaction catalyst is directly fluorinated with inorganic HF before use, it will directly cause the catalyst to have too strong acidity, which will cause the selectivity of the disproportionation reaction of the telomerization substrate dichlorofluoromethane to be much greater than the tendency of dichlorofluoromethane to dissociate into F-, Cl- and other free radicals, and ultimately lead to the main reaction of the telomerization monomer 1,2-difluoroethylene with the disproportionation reaction product to form new substances.

[0012] In addition, in order to effectively reduce the disproportionation reaction of the telogen during the telomerization reaction to produce other by-products, an appropriate amount of promoter is added to the reaction process of the present invention to inhibit the disproportionation reaction of the telogen to a certain extent. The promoter is at least one of chloroform, difluorochloromethane, and chlorofluoromethane. The order of the saturated vapor pressures of the three promoters is difluorochloromethane > chlorofluoromethane > chloroform. Therefore, according to the different saturated vapor pressures, the chloroform promoter with the lowest saturated vapor pressure needs to be added to the reaction kettle first before the reaction, and difluorochloromethane is added last.

[0013] The present invention uses a polar aprotic solvent as the solvent for the reaction system, and the solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, dimethyl sulfoxide, N-methylpyrrolidone, and sulfolane.

[0014] The reaction system of the present invention is carried out in a polymerization reactor, preferably a polymerization reactor made of Monel 400.

[0015] The reaction temperature of the telomerization reaction is 0 to 100 °C, the reaction pressure is 0.1 to 2.0 MPa, and the reaction time is 8 to 24 h; preferably, the reaction temperature is 10 to 80 °C, the reaction pressure is 0.1 to 1.0 MPa, and the reaction time is 10 to 24 h.

[0016] A suitable material ratio in the reaction process may obtain a better reaction effect.

[0017] Further, the mass ratio of the catalyst to 1,2-difluoroethylene in the present invention is (0.001 to 0.5):1; the molar ratio of the promoter to 1,2-difluoroethylene is (0.1 to 1):1, and the molar ratio of the solvent to 1,2-difluoroethylene is (1 to 5):1; preferably, the mass ratio of the catalyst to the raw material is (0.005 to 0.25):1, the molar ratio of the promoter to 1,2-difluoroethylene is (0.5 to 1):1, and the molar ratio of the solvent to 1,2-difluoroethylene is (3 to 5):1.

[0018] Further, the molar ratio of the reaction raw materials 1,2-difluoroethylene and dichlorofluoromethane in the present invention is 1:(0.1 to 10). Preferably, the molar ratio of 1,2-difluoroethylene and dichlorofluoromethane is 1:(1 to 5).

[0019] The 1,2-difluoroethylene described in the present invention is cis-1,2-difluoroethylene and / or trans-1,2-difluoroethylene.

[0020] The present invention uses the combined action of a telomerization catalyst, a promoter, and a polar aprotic solvent to realize a method for liquid-phase telomerization to grow carbon chains. The reaction process is simple, the raw materials are easy to obtain, and the separation is relatively easy.

[0021] In the research process of the present invention, it is found that: thermodynamic theoretical calculations show that the telomerization reaction of 1,2-difluoroethylene and dichlorofluoromethane is an exothermic reaction. Therefore, increasing the reaction temperature may be unfavorable for the progress of this reaction, and a suitable telomerization reaction temperature needs to be screened. The telomerization reaction belongs to a special addition reaction, and its active sites are mainly Lewis acidic sites. The reaction raw material dichlorofluoromethane will activate the C-F or C-Cl bond in the molecule under the action of a Lewis acid telomerization catalyst, and thus dissociate into CHFCl + , CHCl2+ , F - , Cl - Four free radicals. Since the activation energy barrier of dichlorofluoromethane in an acidic catalyst is relatively low (only 0.79 eV), it is prone to disproportionation reaction to form CHCl3 and CHF2Cl. Therefore, chloroform and / or dichlorofluoromethane are added as promoters in the present invention to inhibit the disproportionation reaction of dichlorofluoromethane to a certain extent.

[0022] During the reaction process, by adding a polar aprotic solvent, the reaction system becomes a strongly polar environment, and the affinity between the C-F bond in the telogen dichlorofluoromethane and the telomerization catalyst is increased, thereby inducing the directional dissociation of C-F in dichlorofluoromethane under the action of the supported telomerization catalyst, weakening the dissociation of the C-Cl bond, and improving the ability to make F - directionally add to the terminal C + selectivity. In addition, the supported telomerization catalyst developed in the present invention is moderately pre-fluorinated before the reaction, which can effectively regulate the acid amount and acid strength of the reaction system, reduce the occurrence of the disproportionation reaction of dichlorofluoromethane to a certain extent, and improve the stability of the telomerization catalyst.

[0023] The crude telomerization product of the present invention is obtained by conventional rectification to obtain 3,3-dichloro-1,1,2-trifluoropropane product and by-product 1,3-dichloro-1,2,3-trifluoropropane. The chlorofluoroalkane can be further obtained by dehalogenation process to obtain 1-chloro-2,3,3-trifluoropropene (HCFO-1233yd) and 3-chloro-1,2,3-trifluoropropene (HCFO-1233ye) respectively.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The raw material 1,2-difluoroethylene of the present invention can be prepared by dehydrofluorination of industrial by-product 1,1,2-trifluoroethane (HFC-143). It not only has easily available raw materials and low cost, but also can convert industrial by-product HFC-143 into high-value-added and environmentally friendly fluorine-containing olefin fine chemicals, which not only reduces the by-product treatment cost but also improves the by-product utilization rate.

[0026] 2. The present invention develops a supported telomerization catalyst. Through the synergistic action of a promoter and a polar aprotic solvent, the carbon chain is increased through a one-step telomerization reaction to obtain the target product. Compared with traditional single-component anhydrous chlorides, the used telomerization catalyst is more friendly to the reaction system and reaction equipment, has no corrosion, less dosage, the catalyst can be regenerated, the reaction process is simple, the reaction conditions are mild, the selectivity of the target product is high, and the separation of the catalyst and the product is relatively easy, which is very suitable for industrial application.

[0027] 3. The boiling point of the target product of the present invention (30.2 °C) differs significantly from that of the by-product (101.0 ± 8.0 °C). A product with high purity can be obtained through ordinary distillation or flash distillation, and the unreacted raw materials can also be easily recycled. Detailed implementation manners

[0028] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to these specific implementation manners. Those skilled in the art should recognize that the present invention covers all alternative solutions, improvement solutions, and equivalent solutions that may be included within the scope of the claims.

[0029] Example 1

[0030] This example provides a preparation method for co-producing 3,3-dichloro-1,1,2-trifluoropropane. The preparation method includes the following steps:

[0031] S1. Prepare a 10% ZrCl4 / AC telomerization catalyst using the over-volume impregnation method, and pretreat the catalyst in an atmosphere of 200 °C and dichlorofluoromethane (R21) / N2 = 1:1 for 2 hours to obtain a fluorinated 10% ZrCl4 / AC catalyst.

[0032] S2. Use a 0.5 L autoclave made of Monel 400 as the reactor. Add 3.5 g of the pre-fluorinated 10% ZrCl4 / AC catalyst, 11.9 g (0.1 mol) of chloroform promoter, and 7.8 g (0.1 mol) of dimethyl sulfoxide solvent to the reaction kettle in sequence. Replace the air with nitrogen 3 times, and evacuate the reaction kettle to -0.1 MPa.

[0033] S3. Introduce 25.8 g (0.25 mol) of dichlorofluoromethane, 8.9 g (0.14 mol) of 1,2-difluoroethylene, and 16.4 g (0.19 mol) of chlorodifluoromethane in sequence. Set the reaction temperature to 30 °C, the stirring rate to 400 rpm / min, and the reaction time to 10 h.

[0034] S4. After the reaction, use an air bag to collect the unreacted raw materials 1,2-difluoroethylene and dichlorofluoromethane. As the reaction proceeds, the system pressure gradually decreases from the initial 0.6 MPa to about 0.15 MPa. Filter and separate the reaction liquid in the reaction kettle. The solid part is the reaction catalyst, and the liquid part is obtained by conventional distillation operation to obtain the target product 3,3-dichloro-1,1,2-trifluoropropane.

[0035] The product composition was analyzed by gas chromatography, and the following results were obtained through calculation: the conversion rate of 1,2-difluoroethylene was 92.6%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 84.9%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 13.6%, and the rest were other by-products.

[0036] Example 2

[0037] The operation of this example was the same as that of Example 1, except that: in the telomerization reaction, the reaction temperature was 10 °C, and other operations remained unchanged.

[0038] The telomerization reaction product was analyzed by gas chromatography, and the following results were obtained through calculation: the conversion rate of 1,2-difluoroethylene was 93.8%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 86.1%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 13.4%, and the rest were other by-products.

[0039] Example 3

[0040] The operation of this example was the same as that of Example 1, except that: in the telomerization reaction, the temperature was 50 °C, and other operations remained unchanged.

[0041] The product composition was analyzed by gas chromatography, and the following results were obtained through calculation: the conversion rate of 1,2-difluoroethylene was 83.6%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 76.3%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 19.5%, and the rest were other by-products.

[0042] Example 4

[0043] The operation of this example was the same as that of Example 1, except that: in the telomerization reaction, the temperature was 80 °C, and other operations remained unchanged.

[0044] The product composition was analyzed by gas chromatography, and the following results were obtained through calculation: the conversion rate of 1,2-difluoroethylene was 70.3%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 73.7%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 25.4%, and the rest were other by-products.

[0045] Example 5

[0046] The operation of this example was the same as that of Example 1, except that: in the telomerization reaction, the catalyst was replaced with 3.5 g of 10% AlCl3 / AC, and other conditions remained unchanged.

[0047] The product composition was analyzed by gas chromatography, and the following results were obtained through calculation: the conversion rate of 1,2-difluoroethylene was 90.1%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 78.1%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 18.7%, and the rest were other by-products.

[0048] Example 6

[0049] The operation of this example was the same as that of Example 1, except that: in the telomerization reaction, the catalyst was changed to 3.5 g of 10% GaCl3 / AC, and the others remained unchanged.

[0050] The product composition was analyzed by gas chromatography, and the following results were obtained through calculation: the conversion rate of 1,2-difluoroethylene was 90.9%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 81.5%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 17.9%, and the rest were other by-products.

[0051] Example 7

[0052] The operation of this example was the same as that of Example 1, except that: in the telomerization reaction, the catalyst dosage was increased to 1 time the original amount, that is, 7 g of 10% ZrCl4 / AC, and the others remained unchanged.

[0053] The product composition was analyzed by gas chromatography, and the following results were obtained through calculation: the conversion rate of 1,2-difluoroethylene was 81.7%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 79.1%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 16.7%, and the rest were other by-products.

[0054] Example 8

[0055] The operation of this example was the same as that of Example 1, except that: in the telomerization reaction, the loading amount of the catalyst active component was 5%, that is, 3.5 g of 5% ZrCl4 / AC, and the others remained unchanged.

[0056] The product composition was analyzed by gas chromatography, and the following results were obtained through calculation: the conversion rate of 1,2-difluoroethylene was 86.9%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 84.2%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 12.9%, and the rest were unreacted raw materials and other by-products.

[0057] Example 9

[0058] The operation of this example is the same as that of Example 1, except that: in the telomerization reaction, the molar ratio of raw material 1,2-difluoroethylene to dichlorofluoromethane is 1:1, 8.9 g (0.14 mol) of 1,2-difluoroethylene and 14.4 g (0.14 mol) of dichlorofluoromethane, and the others remain unchanged.

[0059] The product composition was analyzed by gas chromatography and calculated to obtain: the conversion rate of 1,2-difluoroethylene was 77.8%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 71.5%, the selectivity of by-product 1,3-dichloro-1,2,3-trifluoropropane was 20.8%, and the rest were other by-products.

[0060] Example 10

[0061] The operation of this example is the same as that of Example 1, except that: in the telomerization reaction, the molar ratio of raw material 1,2-difluoroethylene to dichlorofluoromethane is 2:1, that is, 16 g (0.25 mol) of 1,2-difluoroethylene and 12.4 g (0.12 mol) of dichlorofluoromethane, and the others remain unchanged.

[0062] The product composition was analyzed by gas chromatography and calculated to obtain: the conversion rate of 1,2-difluoroethylene was 57.6%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 60.2%, the selectivity of by-product 1,3-dichloro-1,2,3-trifluoropropane was 25.6%, and the rest were unreacted raw materials and other by-products.

[0063] Example 11

[0064] The operation of this example is the same as that of Example 1, except that: in the telomerization reaction, the polar aprotic solvent was changed to 10.2 g of N,N-dimethylformamide, and the others remain unchanged.

[0065] The product composition was analyzed by gas chromatography and calculated to obtain: the conversion rate of 1,2-difluoroethylene was 90.1%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 85.5%, the selectivity of by-product 1,3-dichloro-1,2,3-trifluoropropane was 10.5%, and the rest were unreacted raw materials and other by-products.

[0066] Example 12

[0067] The operation of this example is the same as that of Example 1, except that: in the telomerization reaction, the polar aprotic solvent was changed to 16.8 g (0.14 mol) of sulfolane, and the others remain unchanged.

[0068] The product composition was analyzed by gas chromatography, and through calculation, it was obtained that: the conversion rate of 1,2-difluoroethylene was 92.8%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 90.3%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 6.4%, and the rest were unreacted raw materials and other by-products.

[0069] Example 13

[0070] The operation of this example was the same as that of Example 1, with the only difference being that: in the telomerization reaction, the amount of the promoter chloroform was 5.9 g (0.05 mol), and the others remained unchanged.

[0071] The product composition was analyzed by gas chromatography, and through calculation, it was obtained that: the conversion rate of 1,2-difluoroethylene was 88.3%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 72.7%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 15.1%, and the rest were unreacted raw materials and other by-products.

[0072] Comparative Example 1

[0073] The operation of this comparative example was the same as that of Example 1, with the only difference being that: the telomerization catalyst used was 3.5 g of 10% ZnCl2 / AC, and the others remained unchanged.

[0074] The product composition was analyzed by gas chromatography, and through calculation, it was obtained that: 1,2-difluoroethylene did not undergo telomerization reaction, and the target product 3,3-dichloro-1,1,2-trifluoropropane was not obtained in the reaction product.

[0075] Comparative Example 2

[0076] The operation of this comparative example was the same as that of Example 1, with the only difference being that: the promoter chloroform was not added in the telomerization reaction, and the others remained unchanged.

[0077] The product composition was analyzed by gas chromatography, and through calculation, it was obtained that: the conversion rate of 1,2-difluoroethylene was 66.2%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 46.8%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 20.3%, and the rest were the disproportionation reaction products of dichlorofluoromethane and other by-products.

[0078] Comparative Example 3

[0079] The operation of this comparative example was the same as that of Example 1, with the only difference being that: the solvent in the telomerization reaction was 15.4 g (0.1 mol) of the non-polar solvent carbon tetrachloride.

[0080] The composition of the product after rectification was analyzed by gas chromatography. After calculation, it was obtained that the conversion rate of 1,2-difluoroethylene was 83.7%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 63.3%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 28.9%, and the rest were other by-products.

[0081] Comparative Example 4

[0082] The operation of this comparative example was the same as that of Example 1, except that: no polar aprotic solvent was added to the telomerization reaction system, and other conditions remained unchanged.

[0083] The composition of the product after rectification was analyzed by gas chromatography. After calculation, it was obtained that the conversion rate of 1,2-difluoroethylene was 81.6%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 54.9%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 36.6%, and the rest were unreacted raw materials and other by-products.

[0084] Comparative Example 5

[0085] The operation of this comparative example was the same as that of Example 1, except that: the telomerization reaction catalyst was only activated carbon, and other conditions remained unchanged.

[0086] The composition of the product was analyzed by gas chromatography. After calculation, it was obtained that 1,2-difluoroethylene did not undergo an addition reaction and no target product 3,3-dichloro-1,1,2-trifluoropropane was formed.

[0087] Comparative Example 6

[0088] The operation of this comparative example was the same as that of Example 1, except that: the telomerization reaction temperature was 120 °C, and other conditions remained unchanged.

[0089] The composition of the product was analyzed by gas chromatography. After calculation, it was obtained that the conversion rate of 1,2-difluoroethylene was 63.6%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 51.1%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 23.5%, and the rest were the polymerization products of 1,2-difluoroethylene and other by-products.

[0090] Comparative Example 7

[0091] The operation of this comparative example was the same as that of Example 1, except that: the telomerization reaction catalyst 10% ZrCl4 / AC participated in the reaction directly without being pre-fluorinated by the telomerization substrate dichlorofluoromethane (R21), and other conditions remained unchanged.

[0092] The product composition was analyzed by gas chromatography, and the following results were obtained through calculation: the conversion rate of 1,2-difluoroethylene was 77.8%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 64.3%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 9.5%, and the rest were unreacted raw materials and other by-products.

[0093] Comparative Example 8

[0094] The operation of this comparative example was the same as that of Example 5, with the only difference being that the telomerization catalyst 10% AlCl3 / AC participated in the reaction directly without being pre-fluorinated with the telomerization substrate dichlorofluoromethane (R21), and the other conditions remained unchanged.

[0095] The product composition was analyzed by gas chromatography, and the following results were obtained through calculation: the conversion rate of 1,2-difluoroethylene was 69.9%, the selectivity of the product 3,3-dichloro-1,1,2-trifluoropropane was 61.3%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 12.3%, and the rest were unreacted raw materials and other by-products.

[0096] Comparative Example 9

[0097] The operation of this comparative example was the same as that of Example 1, with the only difference being that the telomerization reaction catalyst was pre-fluorinated with inorganic HF, and the other conditions remained unchanged.

[0098] The product composition was analyzed by gas chromatography, and the following results were obtained through calculation: the conversion rate of 1,2-difluoroethylene was 90.6%, the selectivity of the target product 3,3-dichloro-1,1,2-trifluoropropane was 40.2%, the selectivity of the by-product 1,3-dichloro-1,2,3-trifluoropropane was 18.7%, and the selectivity of the remaining 41.1% was the by-product of the side reaction between the R21 disproportionation product dichlorofluoromethane (R22) and the raw material 1,2-difluoroethylene.

Claims

1. A preparation method of 3,3-dichloro-1,1,2-trifluoropropane, characterized in that: 3,3-Dichloro-1,1,2-trifluoropropane is obtained by a one-step telomerization reaction of 1,2-difluoroethylene and dichlorofluoromethane under the combined action of a telomerization catalyst, a promoter, and a polar aprotic solvent.

2. The preparation method of 3,3-dichloro-1,1,2-trifluoropropane according to claim 1, characterized in that: The telomerization catalyst is at least one of AlCl3 / AC, GaCl3 / AC, ZrCl4 / AC, SnCl4 / AC prefluorinated with a halogenated alkane.

3. The preparation method of 3,3-dichloro-1,1,2-trifluoropropane according to claim 2, characterized in that: The halogenated alkane is at least one of chlorodifluoromethane, chlorofluoromethane, and trifluoromethane.

4. The preparation method of 3,3-dichloro-1,1,2-trifluoropropane according to claim 2, characterized in that: The prefluorination temperature of the telomerization catalyst is 200 - 300 °C, and the prefluorination time is 2 - 3 h.

5. The preparation method of 3,3-dichloro-1,1,2-trifluoropropane according to claim 1, characterized in that: The loading amount of the active component in the telomerization catalyst is 5 - 20%.

6. The preparation method of 3,3-dichloro-1,1,2-trifluoropropane according to claim 1, characterized in that: The promoter is at least one of chloroform, chlorodifluoromethane, and chlorofluoromethane.

7. The preparation method of 3,3-dichloro-1,1,2-trifluoropropane according to claim 1, wherein the polar aprotic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, dimethyl sulfoxide, N-methylpyrrolidone, and sulfolane.

8. The preparation method of 3,3-dichloro-1,1,2-trifluoropropane according to claim 1, characterized in that: According to the different saturated vapor pressures, chloroform needs to be added to the reaction kettle before introducing the reaction raw materials, and chlorodifluoromethane and chlorofluoromethane need to be introduced into the reaction kettle before and after introducing the reaction raw materials.

9. The preparation method of 3,3-dichloro-1,1,2-trifluoropropane according to claim 1, wherein: The telomerization reaction temperature is 0 - 100 °C, preferably 10 - 80 °C.

10. The preparation method of 3,3-dichloro-1,1,2-trifluoropropane according to claim 1, characterized in that: The mass ratio of the catalyst dosage to the mass of the raw material 1,2-difluoroethylene is (0.001 - 0.5):1; the molar ratio of the promoter to the raw material 1,2-difluoroethylene is (0.1 - 1):1; the molar ratio of the solvent to the raw material 1,2-difluoroethylene is (1 - 5):

1.

11. The preparation method of 3,3-dichloro-1,1,2-trifluoropropane according to any one of claims 1-10, characterized in that: The liquid product of the telomerization reaction is filtered and separated, and the 3,3-dichloro-1,1,2-trifluoropropane product can be obtained by conventional distillation.

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