A method for preparing 1,2-dichloro-3,3,3-trifluoropropylene

Abstract

This invention provides a method for preparing 1,2-dichloro-3,3,3-trifluoropropene, comprising: Step 1, reacting 2-chloro-3,3,3-trifluoropropene with chlorine gas in the presence of a Lewis catalyst to synthesize 1,2,2-trichloro-3,3,3-trifluoropropane; Step 2, in the presence of a phase transfer catalyst, dehydrochlorinating 1,2,2-trichloro-3,3,3-trifluoropropane in an alkaline solution to prepare 1,2-dichloro-3,3,3-trifluoropropene. This invention employs a two-step reaction route for preparing 1,2-dichloro-3,3,3-trifluoropropene, with mild and controllable reaction conditions. Under preferred conditions, the catalytic chlorination reaction system used in this invention achieves a 100% conversion of 2-chloro-3,3,3-trifluoropropene and a 99.5% selectivity for 1,2,2-trichloro-3,3,3-trifluoropropane.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, and relates to hydrofluoroolefins, specifically to a method for preparing 1,2-dichloro-3,3,3-trifluoropropylene. Background Technology

[0002] Hydrofluoroolefins (HFOs), with zero ozone depletion potential and low greenhouse gas potential, have become a research hotspot in the fluorocarbon industry worldwide. 2,3,3,3-Tetrafluoropropylene (HFO-1234yf) and 1,3,3,3-Tetrafluoropropylene (HFO-1234ze), due to their excellent physicochemical and environmental properties, have become effective refrigerants, foaming agents, fire extinguishing agents, heat transfer media, propellants, gaseous dielectrics, sterilizing agent carriers, power circulation working fluids, polymer monomers, and pharmaceutical and pesticide intermediates, with wide applications. 1,2-Dichloro-3,3,3-trifluoropropylene (HCFO-1223xd) is an important intermediate in the production of HFO-1234yf and HFO-1234ze, and is one of the key technologies for their industrial preparation.

[0003] WO9745388 discloses a method for preparing HFC-245fa by reacting chlorofluoropropane with antimony fluorochloride. HCFO-1223xd is a product with a content that varies in the range of 0.2% to 13.3%, exhibiting low selectivity and low conversion rate.

[0004] US2009043118 discloses a method for reacting 1,1,1-trifluoropropene (HFO-1243zf) with hydrogen fluoride and chlorine in the presence of a gas-phase fluorination catalyst to generate a composition comprising HFO-1234yf, 2,3-dichloro-1,1,1-trifluoropropane (HCFC-243db), 2-chloro-1,1,1-trifluoropropene (HCFO-1233xf), 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb), and HCFO-1223xd, which can serve as a heat transfer composition. In this reaction, the content of HCFO-1223xd generated varies in the range of 0–20.2%, exhibiting low selectivity and low conversion. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing 1,2-dichloro-3,3,3-trifluoropropylene, which solves the technical problems of insufficiently mild reaction conditions and low selectivity in the preparation methods of the existing technology.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for preparing 1,2-dichloro-3,3,3-trifluoropropylene, the method comprising the following steps:

[0008] Step 1: 2-Chloro-3,3,3-trifluoropropene is synthesized by reacting with chlorine gas in the presence of a Lewis catalyst or an ionic salt catalyst to synthesize 1,2,2-trichloro-3,3,3-trifluoropropane.

[0009] Step 2: Under the action of a phase transfer catalyst, 1,2,2-trichloro-3,3,3-trifluoropropane is dehydrochlorinated in an alkaline solution to prepare 1,2-dichloro-3,3,3-trifluoropropene.

[0010] The present invention also has the following technical features:

[0011] Specifically, in step 1, the reaction temperature is 0℃~100℃ and the reaction time is 0.5h~10h; in step 2, the reaction temperature is 30℃~120℃ and the reaction time is 1h~24h.

[0012] Preferably, in step 1, the reaction temperature is 40℃~80℃ and the reaction time is 2h~5h; in step 2, the reaction temperature is 50℃~80℃ and the reaction time is 2h~4h.

[0013] Specifically, in step 1, the Lewis catalyst is ferric chloride, ferric bromide, aluminum chloride, or boron trifluoride.

[0014] Specifically, in step 1, the ionic salt catalyst is a fluorinated titanium salt catalyst with the general formula Q. + [Ti x Cl y F 4x-y+1 ] - Cation Q + It is a quaternary ammonium cation, 1 < x ≤ 2, 0 ≤ y ≤ 4.

[0015] Preferably, in step 1, the quaternary ammonium cation is tetraalkylammonium, trialkylimidazolium, N-alkylpyridinium, or N-alkyl-N-methylpiperidinium.

[0016] More preferably, in step 1, the quaternary ammonium cation is dodecyltrimethylammonium, phenyltrimethylammonium, 1-butyl-2,3-dimethylimidazolium, N-butylpyridinium, N-benzylmethylpyridinium, or N-butyl-N-methylpiperidinium.

[0017] In step 2, the phase transfer catalyst is a crown ether or polyethylene glycol; the alkaline solution is an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide.

[0018] Preferably, in step 2, the crown ether is 15-crown-5, dicyclohexano-18-crown-6, or dibenzo-18-crown-6; and the polyethylene glycol is polyethylene glycol-4000, polyethylene glycol-6000, or polyethylene glycol-8000.

[0019] Specifically, in step 1, the amount of Lewis catalyst used is 0.5 wt% to 5 wt% of the mass of 2-chloro-3,3,3-trifluoropropene; the molar ratio of chlorine gas to 2-chloro-3,3,3-trifluoropropene is 1 to 5:1.

[0020] Specifically, in step 2, the amount of phase transfer catalyst used is 0.5 wt% to 1 wt% of the mass of 1,2,2-trichloro-3,3,3-trifluoropropane; the molar ratio of the base to 1,2,2-trichloro-3,3,3-trifluoropropane is 1 to 5:1.

[0021] Preferably, in step 1, the amount of Lewis catalyst used is 1 wt% to 2 wt% of the mass of 2-chloro-3,3,3-trifluoropropene; and the molar ratio of chlorine gas to 2-chloro-3,3,3-trifluoropropene is 1.5 to 2:1.

[0022] Preferably, in step 2, the amount of phase transfer catalyst is 1 wt% to 3 wt% of the mass of 1,2,2-trichloro-3,3,3-trifluoropropane; and the molar ratio of the base to 1,2,2-trichloro-3,3,3-trifluoropropane is 1.5 to 2:1.

[0023] Compared with the prior art, the present invention has the following technical effects:

[0024] (I) The present invention uses a two-step reaction to prepare 1,2-dichloro-3,3,3-trifluoropropylene, and the reaction conditions are mild and controllable.

[0025] (II) Under preferred conditions, the catalytic chlorination reaction system used in this invention achieves a 100% conversion rate of 2-chloro-3,3,3-trifluoropropene and a 99.5% selectivity for 1,2,2-trichloro-3,3,3-trifluoropropane.

[0026] (III) The present invention employs a phase transfer catalytic system, under optimal conditions, achieving a 100% conversion rate of 1,2,2-trichloro-3,3,3-trifluoropropane and a total selectivity of over 99.0% for 1,2-dichloro-3,3,3-trifluoropropene (cis + trans). Attached Figure Description

[0027] Figure 1 The GC-MS spectrum of 1,2,2-trichloro-3,3,3-trifluoropropane prepared in Example 1 of this invention.

[0028] Figure 2 The GC-MS spectrum of 1,2-dichloro-3,3,3-trifluoropropylene prepared in Example 17 of this invention.

[0029] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, all raw materials used in this invention are those known in the prior art.

[0031] Unless otherwise specified, the scientific and technical terms used herein are intended to be understood by one of ordinary skill in the art. It should also be understood that temperatures and concentrations used herein are approximate and for illustrative purposes. While similar or equivalent methods and materials may be used in the implementation of this disclosure, some suitable methods and materials are described below. Publications, patent applications, patents, and other references mentioned herein are incorporated herein by reference in part, and in case of conflict, this document shall prevail. Furthermore, the materials, methods, solution concentrations, and examples described are exemplary only and are not intended to be limiting. In specific embodiments, those skilled in the art can optimize the proportions, concentrations, and operating parameters of the substances involved in the method using conventional experimental periods based on the disclosure of this invention to achieve the objectives of this invention.

[0032] In this invention, the operating pressure of the reaction is mainly controlled by the saturated vapor pressure of the reactants at the reaction temperature, and is generally not strictly controlled. It can be carried out at pressures below, equal to, or above atmospheric pressure, preferably above atmospheric pressure. Furthermore, the reaction of this invention can be operated intermittently or continuously, and the reaction itself has no significant requirements regarding the reaction mode.

[0033] The present invention will be further described in detail below with reference to the embodiments, but this does not limit the scope of the invention. In the following embodiments, the conversion rate and selectivity of the reactants were detected using GC-MS.

[0034] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0035] Example 1:

[0036] This embodiment provides a method for preparing 1,2,2-trichloro-3,3,3-trifluoropropane, which includes the following steps:

[0037] 65.25 g of 2-chloro-3,3,3-trifluoropropene and 1.31 g of aluminum trichloride were added to a 250 mL stainless steel high-pressure reactor with a stirrer. The temperature was raised to 40 °C, and after stirring was started, 71 g of chlorine gas was introduced to maintain the reaction pressure at 0.3 MPa. The reaction was carried out for 5 h. The temperature was then lowered to stop the reaction. A sample was taken for GC analysis. The conversion rate of 2-chloro-3,3,3-trifluoropropene was 100%, and the selectivity of 1,2,2-trichloro-3,3,3-trifluoropropane was 98.5%.

[0038] The GC-MS analysis of the above product 1,2,2-trichloro-3,3,3-trifluoropropane yielded the following mass spectrometry results: Figure 1 As shown, the relevant peak values ​​are attributed as follows:

[0039] m / z 200 is the molecular ion peak, m / z 165 is the ion peak after Cl removal from CF3CCl2CH2Cl, m / z 151 is the ion peak after CH2Cl removal from CF3CCl2CH2Cl, m / z 131 is the ion peak after CF3CCl2CH2Cl removal from CF3, m / z 95 is the CCl2CH ion peak, m / z 69 is the CF3 ion peak, and m / z 49 is the CH2Cl ion peak.

[0040] The above data proves that the product obtained is 1,2,2-trichloro-3,3,3-trifluoropropane.

[0041] Examples 2-11:

[0042] This embodiment provides a method for preparing 1,2,2-trichloro-3,3,3-trifluoropropane, which is basically the same as the preparation method in Example 16, except that the catalyst and its amount are changed in Examples 2 to 11. The reaction results are shown in Table 1.

[0043] Table 1. Reaction results of Examples 2 to 13

[0044]

[0045]

[0046] The characterization results of the product 1,2,2-trichloro-3,3,3-trifluoropropane in Examples 2 to 11 are basically the same as those in Example 1.

[0047] Examples 12-16:

[0048] This embodiment provides a method for preparing 1,2,2-trichloro-3,3,3-trifluoropropane, which is basically the same as the preparation method in Example 16, except that the molar ratio of chlorine to 2-chloro-3,3,3-trifluoropropene, the reaction temperature and the reaction time are changed in Examples 12 to 16. The reaction results are shown in Table 2.

[0049] Table 2 Reaction results of Examples 12 to 16

[0050]

[0051] The characterization results of the product 1,2,2-trichloro-3,3,3-trifluoropropane in Examples 12 to 16 were basically the same as those in Example 1.

[0052] Example 17:

[0053] This embodiment provides a method for preparing 1,2-dichloro-3,3,3-trifluoropropylene by dehydrochlorination in an alkaline solution. The method includes the following steps:

[0054] 42 g of 40% (mass percentage) KOH aqueous solution, 40.3 g of 1,2,2-trichloro-3,3,3-trifluoropropane, and 0.4 g of polyethylene glycol-4000 (1 wt%) were sequentially added to a reactor equipped with a stirrer. The stirring was started, and the reaction temperature was controlled at 80 °C. After reacting for 4 h, the reactants were cooled to room temperature, and the organic matter was collected after phase separation for gas chromatography analysis. The results showed that the conversion rate of 1,2,2-trichloro-3,3,3-trifluoropropane was 100%, and the conversion rate of (cis+trans)1,2-dichloro-3,3,3-trifluoropropene was 99.5%.

[0055] The GC-MS analysis of the above product, 1,2-dichloro-3,3,3-trifluoropropene, yielded the following mass spectrometry results: Figure 2 As shown, the relevant peak assignments are as follows: m / z 164 is the molecular ion peak, m / z 145 is the ion peak after F removal from CF3CCl=CHCl, m / z 129 is the ion peak after Cl removal from CF3CCl=CHCl, m / z 95 is the ion peak after CF3CCl=CHCl after CF3 removal, and m / z 69 is the CF3 ion peak.

[0056] 1 H NMR (500MHz, CDCl3) δ7.16 (d, J = 1.2Hz, 1H);

[0057] 13 C NMR (126MHz, CDCl3) δ125.65 (q, J = 5.6Hz), 124.68 (q, J = 38.0Hz), 119.87 (q, J = 272.5Hz);

[0058] 19 F NMR (471MHz, CDCl3) δ-68.31.

[0059] The above data proves that the product obtained is 1,2-dichloro-3,3,3-trifluoropropene.

[0060] Example 18:

[0061] This embodiment provides a method for preparing 1,2-dichloro-3,3,3-trifluoropropylene by dehydrochlorination in an alkaline solution. The method includes the following steps:

[0062] 40 g of NaOH (40 wt%) aqueous solution, 40.3 g of 1,2,2-trichloro-3,3,3-trifluoropropane, and 0.2 g of dicyclohexano-18-crown-6 (0.5 wt%) were sequentially added to a stirrer-equipped reactor. The stirring was started, and the reaction temperature was controlled at 120 °C. After reacting for 4 h, the reactants were cooled to room temperature, and the organic matter was collected after phase separation for gas chromatography analysis. The results showed that the conversion rate of 1,2,2-trichloro-3,3,3-trifluoropropane was 100%, and the conversion rate of (cis+trans)1,2-dichloro-3,3,3-trifluoropropene was 98.5%.

[0063] The characterization results of the product 1,2-dichloro-3,3,3-trifluoropropylene in Example 18 were basically the same as those in Example 17.

[0064] Examples 19-22:

[0065] This embodiment provides a method for preparing 1,2-dichloro-3,3,3-trifluoropropylene by dehydrochlorination in an alkaline solution. This method is basically the same as the preparation method in Example 17, except that the catalyst and its amount are changed in Examples 28 to 31. The reaction results are shown in Table 3.

[0066] Table 3 Reaction results of Examples 19 to 22

[0067] 19 15-crown-5 1 100 98.9 20 Dibenzo-18-crown-6 3 100 99.1 21 Polyethylene glycol-6000 3 100 99.3 22 Polyethylene glycol-8000 10 100 97.2

[0068] The characterization results of the products 1,2-dichloro-3,3,3-trifluoropropylene in Examples 19 to 22 were basically the same as those in Example 17.

[0069] Examples 23-27:

[0070] This embodiment provides a method for preparing 1,2-dichloro-3,3,3-trifluoropropene by dehydrochlorination in an alkaline solution. This method is basically the same as the preparation method in Example 17, except that the molar ratio of alkali to 1,2,2-trichloro-3,3,3-trifluoropropane, the reaction temperature, and the reaction time are changed in Examples 23 to 27. The reaction results are shown in Table 4.

[0071] Table 4 shows the reaction results of Examples 23 to 27.

[0072]

[0073] The characterization results of the products 1,2-dichloro-3,3,3-trifluoropropylene in Examples 23 to 27 were basically the same as those in Example 17.

[0074] The above description is only a partial embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing 1,2-dichloro-3,3,3-trifluoropropylene, characterized in that, The method includes the following steps: Step 1: 2-Chloro-3,3,3-trifluoropropene is synthesized by reacting with chlorine gas in the presence of an ionic salt catalyst to synthesize 1,2,2-trichloro-3,3,3-trifluoropropane; In step 1, the ionic salt catalyst is a fluorinated titanium salt catalyst with the general formula Q. + [Ti x Cl y F 4x-y+1 ] - Cation Q + It is a quaternary ammonium cation, 1 < x ≤ 2, 0 ≤ y ≤ 4; Step 2: Under the action of a phase transfer catalyst, 1,2,2-trichloro-3,3,3-trifluoropropane is dehydrochlorinated in an alkaline solution to prepare 1,2-dichloro-3,3,3-trifluoropropene.

2. The method for preparing 1,2-dichloro-3,3,3-trifluoropropylene as described in claim 1, characterized in that, In step 1, the reaction temperature is 0℃~100℃ and the reaction time is 0.5h~10h; in step 2, the reaction temperature is 30℃~120℃ and the reaction time is 1h~24h.

3. The method for preparing 1,2-dichloro-3,3,3-trifluoropropylene as described in claim 2, characterized in that, In step 1, the reaction temperature is 40℃~80℃ and the reaction time is 2h~5h; in step 2, the reaction temperature is 50℃~80℃ and the reaction time is 2h~4h.

4. The method for preparing 1,2-dichloro-3,3,3-trifluoropropylene as described in claim 1, characterized in that, In step 1, the quaternary ammonium cation is tetraalkylammonium, trialkylimidazolium, N-alkylpyridinium, or N-alkyl-N-methylpiperidinium.

5. The method for preparing 1,2-dichloro-3,3,3-trifluoropropylene as described in claim 4, characterized in that, In step 1, the quaternary ammonium cation is dodecyltrimethylammonium, phenyltrimethylammonium, 1-butyl-2,3-dimethylimidazolium, N-butylpyridinium, N-benzylmethylpyridinium, or N-butyl-N-methylpiperidinium.

6. The method for preparing 1,2-dichloro-3,3,3-trifluoropropylene as described in claim 1, characterized in that, In step 2, the phase transfer catalyst is a crown ether or polyethylene glycol; the alkaline solution is an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide.

7. The method for preparing 1,2-dichloro-3,3,3-trifluoropropylene as described in claim 6, characterized in that, In step 2, the crown ether is 15-crown-5, dicyclohexano-18-crown-6, or dibenzo-18-crown-6; the polyethylene glycol is polyethylene glycol-4000, polyethylene glycol-6000, or polyethylene glycol-8000.

8. The method for preparing 1,2-dichloro-3,3,3-trifluoropropylene as described in claim 1, characterized in that, In step 1, the molar ratio of chlorine gas to 2-chloro-3,3,3-trifluoropropene is 1 to 5:1; In step 2, the amount of phase transfer catalyst used is 0.5wt% to 10wt% of the mass of 1,2,2-trichloro-3,3,3-trifluoropropane; the molar ratio of the base to 1,2,2-trichloro-3,3,3-trifluoropropane is 1 to 5:1.

Images