Preparation method of 1-chloro-2, 3, 3-trifluoropropene

Abstract

The invention discloses a preparation method of 1-chloro-2, 3, 3-trifluoropropene, which comprises the following steps: (1) an addition step: carrying out an addition process on chlorotrifluoroethylene and methanol under the action of a free radical initiator to obtain 2-chloro-2, 3, 3-trifluoropropanol; (2) a chlorination step: carrying out a chlorination reaction on the 2-chloro-2, 3, 3-trifluoropropanol under the combined action of a chlorination reagent and a catalyst to obtain 1, 2-dichloro-2, 3, 3-trifluoropropane; and (3) a dehydrochlorination step: carrying out gas phase dehydrochlorination on the 1, 2-dichloro-2, 3, 3-trifluoropropane to obtain the 1-chloro-2, 3, 3-trifluoropropene. The method has the advantages of easily available raw materials, mild reaction conditions, high purity, easiness in separation, suitability for industrial application and the like.

Description

Technical Field

[0001] The present invention relates to the preparation of 1-chloro-2,3,3-trifluoropropene, and particularly to a method for preparing 1-chloro-2,3,3-trifluoropropene by taking chlorotrifluoroethylene as a raw material and successively carrying out three-step reactions of addition, chlorination and dehydrochlorination. Background Art

[0002] 1-chloro-2,3,3-trifluoropropene (abbreviation: HCFO-1233yd) has two cis-trans isomers. The boiling point of cis-HCFO-1233yd (Z) is 54 °C, and the boiling point of trans-HCFO-1233yd (E) is 48 °C. Its ozone depletion potential (ODP) is close to 0, the atmospheric lifetime is about 2.3 days, and GWP 100 = 0.016, it has no flash point, the surface tension and viscosity are also very low, it has good compatibility with mineral oil, has excellent physical and chemical properties, and has great application prospects in application fields such as cleaning agents, refrigerants, foaming agents, aerosols, insulating materials and flame retardants.

[0003] At present, the synthesis of HCFO-1233yd mainly includes the following two routes:

[0004] I. Two-step fluorination route of 1,1,2,3,3-pentachloropropane (HCC-240da)

[0005] Patent CN112125776B of Zibo Leima International Trade Co., Ltd. discloses a method for obtaining HCFO-1233yd by two-step fluorination with 1,1,2,3,3-pentachloropropane (HCC-240da) as the starting material, specifically including: (1) Under the action of a chromium-based catalyst, HCC-240da is fluorinated by hydrogen fluoride to obtain 1,2-dichloro-3,3-difluoropropene (HCFO-1232aa); (2) Under the co-catalysis of a chromium-based catalyst treated with hydrogen fluoride as the main catalyst and at least one of Zn, Co, Ni, and Cu as the co-catalyst, it is fluorinated again to obtain HCFO-1233yd. Among them, in step (1), when the reaction temperature is 275 °C, the space velocity is 240 h -1 、HF:HCC-240da = 15:1, the conversion rate of HCC-240da is 99.6%, and the selectivity of HCFO-1232aa is 90.4%; in step (2), when the reaction temperature is 350 °C, the space velocity is 220 h -1 、HF:HCC-240da = 4:1, the conversion rate of HCFO-1232aa is 65.16%, and the selectivity of HCFO-1233yd is 70.58%.

[0006] However, the starting material of the reaction, 1,1,2,3,3-pentachloropropane (HCC-240da), is a national key controlled elimination substance and cannot be obtained through procurement. It must be prepared by itself (such as by polymerization of trichloromethane and dichloroethylene), which makes the reaction route too long. Both fluorination steps use hydrogen fluoride as the fluorination reagent, which is not only highly corrosive, but also a gas at room temperature. The reaction process requires precise control of the HF / HCC-240da feed ratio to obtain a highly selective intermediate HCFO-1232aa, which is difficult to operate in the industry.

[0007] 2. Five-step process using dichloroethylene and chloroform as raw materials

[0008] AGC patent WO2019189024A discloses a method for obtaining HCFO-1233yd by using dichloroethylene and chloroform as starting materials through a five-step reaction. The method specifically comprises the following steps: (1) 240da is telomerized with dichloroethylene and chloroform under the action of a telomerization catalyst; (2) 240da is dehydrochlorinated under the action of an alkali solution to obtain 1230xd; (3) 1230xd is fluorinated under the action of a gas-phase fluorine-chlorine exchange reaction catalyst to obtain 1232xd; (4) 1232xd is fluorinated under the action of a fluorination catalyst to obtain 1,2-dichloro-2,3,3-trifluoropropane (HCFC-243ba); (5) HCFC-243ba is dehydrochlorinated under the action of an alkali solution to obtain HCFO-1233yd. Specifically, step (1) under the action of AlCl3, 40-45°C telomerization reaction for 28h to obtain 240da, 240da yield of 87.6%; step (2) 48wt% NaOH base catalyst, 19.8g TBAB (tetrabutylammonium bromide, phase shift agent), 50°C, 2.5h to obtain 99.9% purity 1230xd product; step (3) SbF3 fluorine-chlorine exchange catalyst, 130°C gas phase fluorine-chlorine exchange reaction to obtain 53% yield of 1232xd product The product is obtained by using a fluorination catalyst of SbCl5, 80-90°C, 0.95MPa, and reacting for 5h to obtain a 243ba product with a yield of 35.6%. The product is dehydrochlorinated by a liquid phase method at 50°C using a 40% KOH base catalyst, 1.01g TBAC (tetrabutylammonium chloride, a phase shift catalyst), and a conversion rate of 243ba of 98.2%, and the selectivities of HCFO-1233yd (Z) and HCFO-1233yd (E) are 94.2% and 5.7%, respectively. However, the method adopts a five-step method to obtain HCFO-1233yd (Z), which has a long process route and is difficult to control the reaction conditions. The actual yield of the intermediate 243ba prepared by the four-step method in the reaction steps (1) to (4) is only about 35%.

[0009] Therefore, from the perspective of industrialization, for the above two process routes, either the raw materials are not easily obtainable or the operation difficulty is relatively high, and neither of them has the operability and economy for large-scale production. Summary of the Invention

[0010] To solve the above technical problems, the present invention provides a method for preparing 1-chloro-2,3,3-trifluoropropene, which has easily obtainable raw materials, high product selectivity, high purity and easy separation, and is particularly suitable for industrial production.

[0011] The object of the present invention is achieved by the following technical solutions:

[0012] A method for preparing 1-chloro-2,3,3-trifluoropropene, the preparation method comprising:

[0013] (1) Addition step: Trifluorochloroethylene (CTFE) undergoes a radical addition reaction with methanol under the action of an initiator and an acid scavenger to obtain 2-chloro-2,3,3-trifluoropropanol. The reaction formula is as follows:

[0014]

[0015] (2) Chlorination step: 2-chloro-2,3,3-trifluoropropanol undergoes a chlorination reaction under the combined action of a chlorinating reagent and a polar aprotic catalyst to obtain 1,2-dichloro-2,3,3-trifluoropropane. The reaction formula is as follows:

[0016]

[0017] (3) Dehydrochlorination step: 1,2-dichloro-2,3,3-trifluoropropane undergoes a chlorination reaction under the action of a noble metal supported on activated carbon and / or an alkali metal catalyst to obtain 1-chloro-2,3,3-trifluoropropene (HCFO-1233yd). The reaction formula is as follows:

[0018]

[0019] In step (1), the radical initiator is selected from at least one of alkali metals, alkaline earth metals, transition metals, dicarbonate peroxides, hydroperoxides, dialkyl peroxides, and ester peroxides.

[0020] Preferably, the radical initiator is selected from at least one of potassium peroxide, sodium peroxide, magnesium peroxide, barium peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, diisopropyl peroxydicarbonate, di-tert-butyl peroxide, tert-butyl hydroperoxide, 2,5-di-tert-butylperoxy-2,5-dimethylhexane, and tert-butyl peroxybenzoate.

[0021] Further preferably, the radical initiator is preferably at least one of potassium persulfate, sodium persulfate, di-tert-butyl peroxide (DTBP), diisopropyl peroxydicarbonate, and 5-di-tert-butylperoxy-2,5-dimethylhexane (DHBP).

[0022] In step (1), in order to effectively remove the acidic substances that may be generated in the addition reaction and avoid the occurrence of by-products, at least one of sodium oxide, potassium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, iron oxide, manganese oxide, nickel oxide, and copper oxide is used as an acid scavenger; preferably, the acid scavenger is selected from at least one of magnesium oxide, calcium oxide, and barium oxide.

[0023] In step (1), the molar ratio of the raw material chlorotrifluoroethylene to methanol is 1:1 to 10, the molar ratio of the initiator to the raw material is 0.001 to 0.1:1, and the molar ratio of the acid scavenger to chlorotrifluoroethylene is 0.01 to 0.5:1; more preferably, the molar ratio of chlorotrifluoroethylene to methanol is 1:1 to 1.5, the molar ratio of the initiator to chlorotrifluoroethylene is 0.001 to 0.05:1, and the molar ratio of the acid scavenger to chlorotrifluoroethylene is 0.01 to 0.1:1.

[0024] In step (1), the radical addition reaction is carried out in a high-pressure reactor, the reaction temperature is 60 to 150 °C, the reaction time is 1 to 24 h, and the reaction pressure is 1 to 5 MPa; more preferably, the reaction temperature is 80 to 150 °C, and the reaction time is 6 to 10 h.

[0025] In step (2), the chlorinating reagent is selected from at least one of thionyl chloride (SOCl2), sulfuryl chloride (SO2Cl2), hydrochloric acid, oxalyl chloride, carbon tetrachloride, phosphorus trichloride, triphenylphosphine, and phosphorus pentachloride; the catalyst is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, 1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, and hexamethylphosphoric triamide.

[0026] Further preferably, the chlorinating reagent is selected from thionyl chloride (SOCl2) and sulfuryl chloride (SO2Cl2); more preferably, the catalyst is N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0027] In step (2), the molar ratio of the chlorinating reagent to the raw material is 0.5:1 to 2:1, and the molar ratio of the catalyst to the raw material is 0.001:1 to 0.1:1; preferably, the molar ratio of the chlorinating reagent to the raw material is 1:1 to 2:1, and the molar ratio of the catalyst to the raw material is 0.01:1 to 0.1:1.

[0028] In step (2), the chlorination reaction can be carried out in a three-necked glass flask or a chlorination reactor. The chlorination temperature is 20-50°C, the chlorination reaction time is 8-24 h, and the distillation temperature of the crude product is 70-180°C. In order to reduce the material loss during the distillation of the crude product, an organic solvent with a higher boiling point, such as N,N-dimethylformamide, N,N-dimethylacetamide, sulfolane, etc., can be added to the reaction system. Such solvents are soluble in water and can be easily washed away.

[0029] In step (2), the crude chlorination product needs to be washed with alkali after distillation to effectively remove acidic impurities in the product.

[0030] In step (3), the noble metal is selected from at least one of Pt, Pd, Ru, and Rh; the alkali metal is selected from at least one of Li, Na, K, and Cs.

[0031] In step (3), the dehydrochlorination is carried out in a noble metal and / or alkali metal catalyst supported on activated carbon, and the activated carbon is one of granular activated carbon, amorphous activated carbon, coconut shell charcoal, and coal-based charcoal.

[0032] Furthermore, in step (3), the activated carbon needs to be pretreated by at least one of washing with water, acid treatment, and alkali treatment.

[0033] In step (3), the dehydrochlorination reaction pressure is normal pressure, the reaction temperature is 200-400°C, and the reaction space velocity is 100-600 h -1 。

[0034] In step (3), the dehydrochlorination reaction product 1-chloro-2,3,3-trifluoropropene includes cis-1-chloro-2,3,3-trifluoropropene and trans-1-chloro-2,3,3-trifluoropropene.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] 1. The starting material trifluorochloroethylene (CTFE) of the present invention is a raw material with market competitive advantages in our company, and has the advantages of easy availability of raw materials and low production costs; by developing a new process for synthesizing 1-chloro-2,3,3-trifluoropropene, not only the new added value of the trifluorochloroethylene raw material is realized, but also the types and competitiveness of the downstream products of trifluorochloroethylene (CTFE) are enriched.

[0037] 2. In the process for synthesizing 1-chloro-2,3,3-trifluoropropene by the three-step method of the present invention, the selectivities of the intermediates and the target product are both relatively high, and the boiling points differ greatly, so the separation is relatively easy and the purity is high, and the three wastes are less. The unreacted raw materials or intermediates can be recycled and reused, and the separation cost of reaction impurities is effectively reduced; in addition, the reaction conditions of this process are mild, the process is relatively simple and feasible, and it is very suitable for industrial scale-up production. Detailed Embodiments

[0038] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to these specific embodiments. 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.

[0039] Example 1

[0040] This example provides a method for preparing 1-chloro-2,3,3-trifluoropropene, which specifically includes the following steps:

[0041] (1) Addition step:

[0042] A1. Respectively add 20.8 g of anhydrous methanol (0.65 mol), 2.3 g of potassium persulfate (0.0085 mol), and 1.2 g of calcium oxide (0.021 mol) into a 0.5 L high-pressure reactor, introduce 0.6 MPa of nitrogen to displace the air in the reactor, and repeat 3 times;

[0043] A2. Place the reactor in a -50 °C low-temperature cooling bath to lower the internal temperature of the reaction to below -40 °C, introduce 75 g (0.65 mol) of chlorotrifluoroethylene, and after the feeding is completed, restore the reactor to room temperature and transfer it to a temperature-controlled stirring platform;

[0044] A3. Set the reactor temperature to 80 °C, the stirring rate to 500 rpm, the initial reaction pressure to 2 MPa, and the reaction time to 8 h;

[0045] A4. After the reaction is completed, collect the gas-phase and liquid-phase products respectively, analyze the product composition by gas chromatography, and obtain a conversion rate of chlorotrifluoroethylene of 60.4%, a selectivity of 2-chloro-2,3,3-trifluoro-1-propanol of 69.6%, and a selectivity of by-product 3-chloro-2,2,3-trifluoro-1-propanol of 29.5% through calculation;

[0046] (2) Chlorination step

[0047] B1. Add 168.5 g (1.13 mol) of 2-chloro-2,3,3-trifluoro-1-propanol and 1.69 g (0.023 mol) of N,N-dimethylformamide (DMF) into a 250 ml three-necked flask respectively;

[0048] B2. Gradually add 134.47 g (1.13 mol) of thionyl chloride (SOCl2) dropwise to the S1 mixture through a constant pressure dropping funnel, and continuously react at 30 °C for 12 h;

[0049] B3. Add 56 g of DMF to the reaction solution obtained in S2. Connect the reactor to a conventional distillation apparatus, heat the temperature of the still pot to 90 - 100 °C, and collect the liquefied product condensed at the top of the column through a condenser.

[0050] B4. Wash the condensed and liquefied product with 10% KOH aqueous solution to remove acid, and recover 157.6 g of 1,2-dichloro-2,3,3-trifluoropropane product with a purity of over 99%. The conversion rate of the raw material and the selectivity of 1,2-dichloro-2,3,3-trifluoropropane are 96.1% and 97.7% respectively by gas chromatography analysis.

[0051] (3) Dehydrochlorination step

[0052] C1. Use a Monel reaction tube with an inner diameter of 8 mm and a length of 600 mm as the gas-phase dehydrochlorination reactor, and pack 5 ml of 1% Ru / AC (AC represents activated carbon) catalyst with a size of 40 - 60 mesh into the catalyst bed of the reactor.

[0053] C2. Set the reaction temperature to 300 °C, the heating rate to 5 K / min, heat up by passing nitrogen, and after reaching the preset temperature and stabilizing for 0.5 h, pass the reaction raw materials.

[0054] C3. Vaporize the raw material 1,2-dichloro-2,3,3-trifluoropropane in a vaporizer at 110 °C and then introduce it into the reactor, and control the reaction space velocity to be 240 h -1 ;

[0055] C4. Collect the reaction products, and analyze the composition of the products by gas chromatography. It is found through calculation that the conversion rate of 1,2-dichloro-2,3,3-trifluoropropane is 97.3%, the selectivity of cis-1-chloro-2,3,3-trifluoropropene is 83.8%, and the selectivity of trans-1-chloro-2,3,3-trifluoropropene is 11.4%.

[0056] Example 2

[0057] The operation of this example is the same as that of Example 1, except that: in reaction step one, the deacidifying agent is changed to 0.84 g (0.021 mol) of magnesium oxide, and other conditions remain unchanged. The reaction products are analyzed by gas chromatography. The conversion rate of trichloroethylene is 59.3%, the selectivity of 2-chloro-2,3,3-trifluoro-1-propanol is 67.1%, and the selectivity of by-product 3-chloro-2,2,3-trifluoro-1-propanol is 28.7%.

[0058] Example 3

[0059] The operation of this example is the same as that of Example 1, except that: in the first reaction step, the deacidifying agent is changed to 3.2 g (0.021 mol) of barium oxide, and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of chlorotrifluoroethylene is 63.2%, the selectivity of 2-chloro-2,3,3-trifluoropropanol is 68.9%, and the selectivity of by-product 3-chloro-2,2,3-trifluoropropanol is 30.1%.

[0060] Example 4

[0061] The operation of this example is the same as that of Example 1, except that: in the first reaction step, the addition reaction temperature is 100 °C, and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of chlorotrifluoroethylene is 72.4%, the selectivity of 2-chloro-2,3,3-trifluoropropanol is 77.3%, and the selectivity of by-product 3-chloro-2,2,3-trifluoropropanol is 21.3%.

[0062] Example 5

[0063] The operation of this example is the same as that of Example 1, except that: in the first reaction step, the addition reaction temperature is 150 °C, and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of chlorotrifluoroethylene is 79.5%, the selectivity of 2-chloro-2,3,3-trifluoropropanol is 81.4%, and the selectivity of by-product 3-chloro-2,2,3-trifluoropropanol is 9.1%.

[0064] Example 6

[0065] The operation of this example is the same as that of Example 1, except that: in the first reaction step, the methanol in the addition reaction raw materials is 41.6 g (1.3 mol), and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of chlorotrifluoroethylene is 65.8%, the selectivity of 2-chloro-2,3,3-trifluoropropanol is 73.6%, and the selectivity of by-product 3-chloro-2,2,3-trifluoropropanol is 22.9%.

[0066] Example 7

[0067] The operation of this example is the same as that of Example 1, except that: in the first reaction step, the initiator of the addition reaction is 4.6 g of potassium persulfate (0.017 mol), and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of chlorotrifluoroethylene is 70.7%, the selectivity of 2-chloro-2,3,3-trifluoropropanol is 75.2%, and the selectivity of by-product 3-chloro-2,2,3-trifluoropropanol is 19.7%.

[0068] Example 8

[0069] The operation of this example is the same as that of Example 1, except that: in the first step of the reaction, the initiator for the addition reaction is 4.5 g (0.031 mol) of di-tert-butyl peroxide (DTBP), and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of chlorotrifluoroethylene is 76.3%, the selectivity for 2-chloro-2,3,3-trifluoropropanol is 76.6%, and the selectivity for the by-product 3-chloro-2,2,3-trifluoropropanol is 18.1%.

[0070] Example 9

[0071] The operation of this example is the same as that of Example 6, except that: in the first step of the reaction, the temperature of the addition reaction is 150 °C, and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of chlorotrifluoroethylene is 80.3%, the selectivity for 2-chloro-2,3,3-trifluoropropanol is 85.6%, and the selectivity for the by-product 3-chloro-2,2,3-trifluoropropanol is 13.9%.

[0072] Example 10

[0073] The operation of this example is the same as that of Example 7, except that: in the first step of the reaction, the feeding amount of methanol as the raw material for the addition reaction is 88.7 g (2.6 mol), and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of chlorotrifluoroethylene is 91.1%, the selectivity for 2-chloro-2,3,3-trifluoropropanol is 90.3%, and the selectivity for the by-product 3-chloro-2,2,3-trifluoropropanol is 7.3%.

[0074] Example 11

[0075] The operation of this example is the same as that of Example 1, except that: in the third step of the reaction, the temperature of the dehydrochlorination reaction is changed to 350 °C, and other conditions remain unchanged. After calculation, it is found that the conversion rate of 1,2-dichloro-2,3,3-trifluoropropane is 98.3%, the selectivity for cis-1-chloro-2,3,3-trifluoropropene is 82.3%, and the selectivity for trans-1-chloro-2,3,3-trifluoropropene is 13.7%.

[0076] Example 12

[0077] The operation of this example is the same as that of Example 1, except that: in the third step of the reaction, the temperature of the dehydrochlorination reaction is changed to 400 °C, and other conditions remain unchanged. After calculation, it is found that the conversion rate of 1,2-dichloro-2,3,3-trifluoropropane is 98.9%, the selectivity for cis-1-chloro-2,3,3-trifluoropropene is 78.3%, and the selectivity for trans-1-chloro-2,3,3-trifluoropropene is 16.4%.

[0078] Example 13

[0079] The operation of this example is the same as that of Example 1, except that: in reaction step three, the dehydrochlorination reaction catalyst is changed to 10% CsCl / AC, and other conditions remain unchanged. After calculation, it is found that the conversion rate of 1,2-dichloro-2,3,3-trifluoropropane is 98.5%, the selectivity of cis-1-chloro-2,3,3-trifluoropropene is 83.3%, and the selectivity of trans-1-chloro-2,3,3-trifluoropropene is 13.1%.

[0080] Example 14

[0081] The operation of this example is the same as that of Example 1, except that: in reaction step three, the dehydrochlorination catalyst is changed to 10% KCl / AC, and other conditions remain unchanged. After calculation, it is found that the conversion rate of 1,2-dichloro-2,3,3-trifluoropropane is 97.9%, the selectivity of cis-1-chloro-2,3,3-trifluoropropene is 82.5%, and the selectivity of trans-1-chloro-2,3,3-trifluoropropene is 14.7%.

[0082] Example 15

[0083] The operation of this example is the same as that of Example 1, except that: in reaction step three, the dehydrochlorination catalyst is changed to 1% Ru-10% KCl / AC, and other conditions remain unchanged. After calculation, it is found that the conversion rate of 1,2-dichloro-2,3,3-trifluoropropane is 99.1%, the selectivity of cis-1-chloro-2,3,3-trifluoropropene is 90.8%, and the selectivity of trans-1-chloro-2,3,3-trifluoropropene is 8.7%.

[0084] Example 16

[0085] The operation of this example is the same as that of Example 16, except that: in reaction step one, the space velocity of the dehydrofluorination reaction is 360 h -1 , and other conditions remain unchanged. After calculation, it is found that the conversion rate of 1,2-dichloro-2,3,3-trifluoropropane is 97.3%, the selectivity of cis-1-chloro-2,3,3-trifluoropropene is 85.9%, and the selectivity of trans-1-chloro-2,3,3-trifluoropropene is 8.8%.

[0086] Comparative Example 1

[0087] The operation of this example is the same as that of Example 1, except that: in reaction step one, no acid scavenger is added in the addition reaction, and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of trifluorochloroethylene is 35.6%, the selectivity of 2-chloro-2,3,3-trifluoropropanol is 44.1%, the selectivity of by-product 3-chloro-2,2,3-trifluoropropanol is 33.5%, and the content of other unknown impurities is 22.4%.

[0088] Comparative Example 2

[0089] The operation of this example is the same as that of Example 1, with the only difference being that in the first step of the reaction, in the addition reaction, an organic base, triethylamine, is added as an acid scavenger, and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of chlorotrifluoroethylene is 29.7%, the selectivity of 2-chloro-2,3,3-trifluoropropanol is 36.5%, the selectivity of the by-product 3-chloro-2,2,3-trifluoropropanol is 17.4%, and the content of other unknown impurities is 46.1%.

[0090] Comparative Example 3

[0091] The operation of this example is the same as that of Example 1, with the only difference being that in the second step of the reaction, the chlorination reagent in the chlorination reaction is 47.067 g (0.39 mol), and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of the raw material 2-chloro-2,3,3-trifluoropropanol is 56.7%, the selectivity of the reaction product 1,2-dichloro-2,3,3-trifluoropropane is 95.1%, and the rest are other impurities.

[0092] Comparative Example 4

[0093] The operation of this example is the same as that of Example 1, with the only difference being that in the second step of the reaction, the catalyst for the chlorination reaction is replaced with 0.74 g (0.023 mol) of polar proton solvent methanol, and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of the raw material 2-chloro-2,3,3-trifluoropropanol is 7.9%, the selectivity of the reaction product 1,2-dichloro-2,3,3-trifluoropropane is 66.9%, and the rest are other impurities.

[0094] Comparative Example 5

[0095] The operation of this example is the same as that of Example 1, with the only difference being that in the third step of the reaction, the catalyst for the dehydrochlorination reaction is replaced with Ir / AC, and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of 1,2-dichloro-2,3,3-trifluoropropane is 64.3%, the selectivity of cis-1-chloro-2,3,3-trifluoropropene is 67.8%, and the selectivity of trans-1-chloro-2,3,3-trifluoropropene is 9.5%.

[0096] Comparative Example 6

[0097] The operation of this example is the same as that of Example 1, with the only difference being that in the third step of the reaction, the catalyst for the dehydrochlorination reaction is only KCl, and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of 1,2-dichloro-2,3,3-trifluoropropane is 55.3%, the selectivity of cis-1-chloro-2,3,3-trifluoropropene is 63.8%, and the selectivity of trans-1-chloro-2,3,3-trifluoropropene is 11.4%.

[0098] Comparative Example 7

[0099] The operation of this example is the same as that of Example 1, with the only difference being that in reaction step three, the dehydrochlorination reaction catalyst is only AlF3, and other conditions remain unchanged. The reaction product is analyzed by gas chromatography. The conversion rate of 1,2-dichloro-2,3,3-trifluoropropane is 75.3%, the selectivity of 1-chloro-2,3,3-trifluoropropene is 0, and the selectivity of 2,3-dichloro-1,1-difluoropropene is 96.7%.

[0100] Comparative Example 8

[0101] The operation of this example is the same as that of Example 1, with the only difference being that in reaction step three, the activated carbon support of the dehydrochlorination catalyst is not pretreated, that is, 10% KCl / AC - untreated, and other conditions remain unchanged. After calculation, it is found that the conversion rate of 1,2-dichloro-2,3,3-trifluoropropane is 67.6%, the selectivity of cis-1-chloro-2,3,3-trifluoropropene is 54.5%, the selectivity of trans-1-chloro-2,3,3-trifluoropropene is 13.8%, and other impurities are 31.7%.

[0102] Comparative Example 9

[0103] The operation of this example is the same as that of Example 1, with the only difference being that in reaction step three, the activated carbon support of the dehydrochlorination catalyst is not pretreated, that is, 1% Ru-10% KCl / AC - untreated, and other conditions remain unchanged. After calculation, it is found that the conversion rate of 1,2-dichloro-2,3,3-trifluoropropane is 75.1%, the selectivity of cis-1-chloro-2,3,3-trifluoropropene is 63.5%, the selectivity of trans-1-chloro-2,3,3-trifluoropropene is 11.3%, and other impurities are 25.2%.

Claims

1. A method for preparing 1-chloro-2,3,3-trifluoropropene, characterized in that: The preparation method includes the following steps: (1) Addition step: Chlorotrifluoroethylene and methanol react under the combined action of an initiator and an acid scavenger to obtain 2-chloro-2,3,3-trifluoropropanol. The initiator is selected from at least one of alkali metals, alkaline earth metals, transition metals, dicarbonate peroxides, hydroperoxides, dialkyl peroxides, and ester peroxides; the acid scavenger is selected from at least one of sodium oxide, potassium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, iron oxide, manganese oxide, nickel oxide, and copper oxide. (2) Chlorination step: 2-chloro-2,3,3-trifluoropropanol reacts under the combined action of a chlorinating reagent and a polar aprotic catalyst to obtain 1,2-dichloro-2,3,3-trifluoropropane through a chlorination reaction. (3) Dehydrochlorination step: 1,2-dichloro-2,3,3-trifluoropropane reacts under the action of a noble metal supported on activated carbon and / or an alkali metal catalyst to obtain 1-chloro-2,3,3-trifluoropropene through a dehydrochlorination reaction.

2. The preparation method of 1-chloro-2,3,3-trifluoropropene according to claim 2, characterized in that: The acid scavenger is selected from at least one of magnesium oxide, calcium oxide, and barium oxide.

3. The preparation method of 1-chloro-2,3,3-trifluoropropene according to claim 1, wherein: In step (1), the molar ratio of chlorotrifluoroethylene to methanol is 1:1 to 10, the molar ratio of the initiator to chlorotrifluoroethylene is 0.001 to 0.1:1, and the molar ratio of the acid scavenger to chlorotrifluoroethylene is 0.01 to 0.5:

1.

4. The preparation method of 1-chloro-2,3,3-trifluoropropene according to claim 5, characterized in that: In step (1), the reaction temperature is 60 to 150 °C, the reaction pressure is 1 to 5 MPa, and the reaction time is 1 to 24 h.

5. The preparation method of 1-chloro-2,3,3-trifluoropropene according to claim 1, characterized in that: In step (2), the chlorinating reagent is selected from at least one of thionyl chloride, oxalyl chloride, carbon tetrachloride, phosphorus trichloride, triphenylphosphine, and phosphorus pentachloride; the catalyst is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, 1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, and hexamethylphosphoric triamide.

6. The method for preparing 1-chloro-2,3,3-trifluoropropene according to claim 1, characterized in that: In step (2), the molar ratio of the chlorinating reagent to the raw material is 0.5:1 to 2:1, and the mass ratio of the catalyst to the raw material is 0.0001:1 to 0.01:

1.

7. The method for preparing 1-chloro-2,3,3-trifluoropropene according to claim 1, characterized in that: In step (3), the noble metal is selected from at least one of Pt, Pd, Ru, and Rh; the alkali metal is selected from at least one of Li, Na, K, and Cs.

8. The preparation method of 1-chloro-2,3,3-trifluoropropene according to claim 1, characterized in that: In step (3), the activated carbon is selected from one of granular activated carbon, amorphous activated carbon, coconut shell charcoal, and coal-based charcoal.

9. The method for preparing 1-chloro-2,3,3-trifluoropropene according to claim 1, characterized in that: In step (3), the activated carbon needs to be pretreated by at least one of washing with water, pickling, or alkali washing.

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