Preparation method of 3, 3, 3-trifluoro-1-propyne

Abstract

The invention discloses a preparation method of 3, 3, 3-trifluoro-1-propyne, which comprises the following steps: (1) taking E-1-chloro-3, 3, 3-propylene as a raw material, and carrying out chlorine or bromine addition to obtain a compound as shown in a formula (I); (2) in a first solvent, in the presence of alkali, the compound shown in the formula (I) is subjected to an elimination reaction to obtain 1, 2-diX-3, 3, 3-trifluoropropene shown in the following formula (II) and / or 2-X-1-chloro-3, 3, 3-trifluoropropene shown in the following formula (III), X is chlorine or bromine, when X is chlorine, the structures of the formula (II) and the formula (III) are the same, and the formula (II) and the formula (III) are 1, 2-dichloro-3, 3, 3-trifluoropropene; and (3) in a second solvent, in the presence of a reducing agent, carrying out elimination reaction on the compound as shown in the formula (II) and / or the formula (III) to obtain the 3, 3, 3-trifluoro-1-propyne. According to the method, the trifluoropropyne is prepared by taking E-1233zd as a raw material, the technical problems of low conversion rate and poor selectivity in the process of preparing the trifluoropropyne through an E-1233zd raw material route are solved, the raw materials are easy to obtain, the cost is low, the method is very suitable for industrial application, and the market competitiveness of the product can be greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of synthesis of fluorinated organic compounds, and particularly to a method for preparing 3,3,3-trifluoro-1-propyne. Background Art

[0002] 3,3,3-Trifluoro-1-propyne, with the molecular formula C3HF3, is abbreviated as TFPY in English. Its boiling point is -48.3 °C, flash point is -94.5 ± 13.9 °C, density is 1.2 g / cm 3 , GWP 1.4, ODP is negligible, non-toxic, and needs to be stored away from light and isolated from air. TFPY is a new type of refrigerant with low GWP. It can be used as an anti-corrosion agent, aerosol, foaming agent, and can also be used for synthesizing monomers of pharmaceutical intermediates and high molecular compounds. It is a very important fluorinated industrial product.

[0003] Currently, the preparation methods of TFPY mainly include liquid-phase elimination process and gas-phase dehydrohalogenation process. Among them, the gas-phase dehydrohalogenation process generally has problems such as low catalyst activity, low raw material conversion rate, and low yield, which are difficult to meet the requirements of industrial production. The liquid-phase elimination process is more applied in industrial production. The liquid-phase elimination process route mainly includes the following two:

[0004] I. Dehydrohalogenation Process

[0005] This process uses 1-X-3,3,3-trifluoropropene and 2-X-3,3,3-trifluoropropene (X = F, Cl, Br, and I) as raw materials, and obtains TFPY after eliminating hydrogen halide under the action of a base. This reaction type is an E2 reaction. When X is Br and I, the preparation process of the raw materials is complex and the cost is high, and the advantage of industrial application is low. The most common preparation process is based on 1-chloro-3,3,3-trifluoropropene (1233zd) as the raw material.

[0006] Patent CN101675017A discloses a method for preparing TFPY using Z-1233zd as the raw material. It uses potassium hydroxide as the base, water and methanol as the solvents, and reacts at 38 °C. The conversion rate of the raw material Z-1233zd is 98.6%, the selectivity of the product TFPY is 98.3%, and the yield is 96.9%. However, when the raw material is E-1233zd and reacts under the same conditions, no product is formed at all.

[0007] Patent WO2014 / 099464A1 discloses a method for preparing TFPY from E-1233zd. In a 600 mL stainless steel reactor, 106 g of 50% w / v KOH solution, 2 g of quaternary ammonium salt and 108 g of deionized water were added. After the reactor was sealed, it was evacuated and purged with nitrogen three times, and the reaction was carried out at 50 °C for 20 h. In the collected gas-phase product, the content of 3,3,3-trifluoropropyne was 4.09%, and the content of the raw material E-1233zd was 91.04%. It can be seen that a large amount of raw materials were not converted and almost no reaction occurred.

[0008] Although patent CN104936935A discloses a method for preparing TFPY from E-1233zd, this method not only needs to be carried out at low temperature, with cumbersome operation, but also has a very low reaction yield. The operation process disclosed in its examples is as follows: at -30 °C, sodium amide (5.5 g, 90%) was slowly added to 6 g of E-1233zd in 60 mL of tetrahydrofuran, the temperature was controlled below -20 °C, and the mixture was stirred in a nitrogen atmosphere for 2 h. Then, a dilute hydrochloric acid solution was added at -20 °C, and the product was collected in a dry ice-acetone trap at -70 °C through a reflux condenser controlled at -5 to 0 °C. After hydrolysis, the mixture was refluxed for another 2 h to drive out all TFPY. 7.2 g of clear liquid was collected. GC analysis showed that the content of TFPY was 31.67%, the content of E-1233zd was 1.90%, and the content of tetrahydrofuran was 63.70%.

[0009] Therefore, in the current liquid-phase dehydrohalogenation process for preparing TFPY, basically Z-1233zd is used as the raw material to obtain a higher raw material conversion rate and reaction yield. However, the raw material Z-1233zd is not easily obtained and it is difficult to meet industrial production requirements. As a new type of refrigerant, E-1233zd is a marketable industrial product and is easily obtained. However, for its elimination reaction, not only more stringent reaction conditions are required, such as using a stronger base and controlling low temperature, but the key problem is that its reaction yield is low, the cost is high, and it is uneconomical.

[0010] When preparing TFPY by gas-phase dehydrohalogenation, whether Z-1233zd or E-1233zd is used as the raw material, the raw material conversion rate is relatively low and the TFPY yield is also very low.

[0011] II. Dehalogenation process

[0012] This process uses 1,2 - diX - 3,3,3 - trifluoropropene (X = Cl and Br) as the raw material. Under the action of active metals (such as zinc powder and magnesium chips), after one - step elimination of halogen, TFPY is directly obtained. This reaction type is an E1cB reaction. The Henne laboratory reported a process for preparing TFPY using 1,2 - dibromo - 3,3,3 - trifluoropropene as the raw material. This method uses absolute ethanol as the solvent and refluxes the reaction under the action of zinc powder, and the final reaction yield reaches 97%. However, the raw material preparation process used in this method is relatively complex, with high costs, and the bromination reaction involved has high requirements for equipment. Therefore, its market competition advantage is relatively low.

[0013] Therefore, it is very necessary to develop a preparation process for 3,3,3 - trifluoro - 1 - propyne that has easily available raw materials, mild reaction conditions, high reaction yield, low production cost, is safe and environmentally friendly, and is suitable for industrial application. Summary of the Invention

[0014] To solve the above - mentioned technical problems, the present invention provides a preparation method for 3,3,3 - trifluoro - 1 - propyne compounds that has simple and easily available raw materials, low production cost, high reaction yield, simple operation, recyclable solvent, low amount of three wastes, and is very suitable for industrial application.

[0015] The object of the present invention is achieved through the following technical solutions:

[0016] (1) Using E - 1 - chloro - 3,3,3 - propene as the raw material, adding chlorine or bromine to obtain the compound shown in the following formula (I);

[0017] (2) In the first solvent, in the presence of a base, the compound shown in formula (I) undergoes an elimination reaction to obtain 1,2 - diX - 3,3,3 - trifluoropropene shown in the following formula (II) and / or 2 - X - 1 - chloro - 3,3,3 - trifluoropropene shown in the following formula (III);

[0018] (3) In the second solvent, in the presence of a reducing agent, the compound shown in formula (II) and / or formula (III) undergoes an elimination reaction to obtain 3,3,3 - trifluoro - 1 - propyne shown in formula (IV);

[0019] The reaction equations are as follows:

[0020]

[0021] In the formula, X is chlorine or bromine; when X is chlorine, the compounds of formula (II) and formula (III) are the same, which is 1,2 - dichloro - 3,3,3 - trifluoropropene.

[0022] In step (2), the base is selected from at least one of alkali metal hydroxides, alkali metal alkoxides, and alkali metal amides. The alkali metal hydroxide is selected from at least one of lithium hydroxide, sodium hydroxide, or potassium hydroxide. The alkali metal alkoxide is selected from at least one of sodium methoxide, sodium ethoxide, potassium ethoxide, sodium tert-butoxide, or potassium tert-butoxide. The alkali metal amide is preferably sodium amide. Preferably, the base is selected from at least one of sodium hydroxide, potassium hydroxide, sodium ethoxide, or potassium tert-butoxide.

[0023] In step (2), the first solvent is selected from at least one of water, alcohol solvents, ether solvents, nitrile solvents, amide solvents, or sulfone solvents. The alcohol solvent is selected from at least one of methanol, ethanol, propanol, isopropanol, ethylene glycol, or diethylene glycol. The ether solvent is selected from at least one of tetrahydrofuran, diethyl ether, or dioxane. The nitrile solvent is selected from at least one of acetonitrile, propionitrile, or butyronitrile. The amide solvent is selected from at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), or hexamethylphosphoric triamide (HMPA). The sulfone solvent is selected from at least one of dimethyl sulfoxide (DMSO) and / or sulfolane. Preferably, the first solvent is selected from at least one of water, methanol, ethanol, propanol, isopropanol, ethylene glycol, or diethylene glycol.

[0024] In step (2), the molar ratio of the compound represented by formula (I) to the base is 1:(1 - 5), and preferably the molar ratio is 1:(1.2 - 2.5).

[0025] In step (2), the mass ratio of the compound represented by formula (I) to the first solvent is 1:(1 - 5), and preferably the molar ratio is 1:(2 - 3).

[0026] In a preferred embodiment, step (2) uses sodium hydroxide as the base and water as the solvent. In this way, not only can the compounds of formula (II) and / or formula (III) be obtained efficiently, but the three wastes are saline wastewater, which is simple to treat and has low production costs.

[0027] In step (3), the second solvent is selected from at least one of methanol, ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol, tetrahydrofuran, diethyl ether, dioxane, acetonitrile, propionitrile, butyronitrile, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), hexamethylphosphoric triamide (HMPA), dimethyl sulfoxide (DMSO), or sulfolane, etc. Preferably, the second solvent is selected from at least one of methanol, ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol, N,N-dimethylformamide (DMF), or N,N-dimethylacetamide (DMAC).

[0028] In step (3), the reducing agent is selected from at least one of zinc powder, magnesium chips, or iron powder, and preferably zinc powder and / or magnesium chips.

[0029] Step (3) of the present invention is preferably carried out in the presence of an initiator. The main function of the initiator is to activate the metal surface, improve the reactivity of the metal, and effectively increase the reaction yield. The initiator is selected from zinc chloride, 1,2-dibromoethane, Br2, I2, hydrochloric acid, propionic acid, oxalic acid, etc., preferably zinc chloride or I2.

[0030] Step (3) of the present invention is preferably carried out in the presence of an additive, which can reduce the self-polymerization of the product and increase the product yield. The additive is selected from one of phenolic compounds, quinone compounds, aromatic amine compounds, phenylhydrazine compounds, ferric chloride, sodium sulfide, ammonium thiocyanate, or cuprous oxide.

[0031] Specifically, the phenolic compound is selected from at least one of phenol, hydroquinone, 4-methoxyphenol, 4-tert-butyl-2,6-dimethylphenol, 4,4'-dihydroxybiphenyl, or bisphenol A;

[0032] The quinone compound is selected from at least one of tetrachlorobenzoquinone, p-benzoquinone, or 1,4-naphthoquinone;

[0033] The aromatic amine compound is selected from at least one of 4-methylaniline, diphenylamine, benzidine, p-phenylenediamine, or N-nitrosodiphenylamine;

[0034] The phenylhydrazine compound is selected from at least one of 1,1-diphenyl-2-trinitrophenylhydrazine or N,N-diphenyl-N-2,4,6-trinitrophenylhydrazine.

[0035] In step (3), the molar ratio of the compound shown in formula (II) and / or formula (III) to the reducing agent is 1:(1 - 5), preferably 1:(1.2 - 2.5).

[0036] In step (3), the molar ratio of the compound shown in formula (II) and / or formula (III) to the initiator is 1:(0.01% - 1%), preferably 1:(0.01% - 0.1%)

[0037] In step (3), the molar ratio of the compound shown in formula (II) and / or formula (III) to the additive is 1:(0.1% - 1%), preferably (0.1% - 0.5%).

[0038] In step (3), the mass ratio of the compound shown in formula (II) and / or formula (III) to the second solvent is 1:(1 - 5), preferably 1:(2 - 3).

[0039] In step (1) of the present invention, the reaction temperature is -5 to 100 °C, and the reaction time is 1 to 10 h; preferably, the reaction temperature is room temperature to 100 °C, and the reaction time is 3 to 10 h.

[0040] In step (2) of the present invention, the reaction temperature is -20 to 120 °C, and the reaction time is 2 to 4 h; preferably, the reaction temperature is -20 to 80 °C, and the reaction time is 3 to 4 h.

[0041] In step (3) of the present invention, the reaction temperature is 25 to 140 °C, and the reaction time is 2 to 6 h; preferably, the reaction temperature is 60 to 100 °C, and the reaction time is 2 to 4 h.

[0042] The specific operation steps of step (1) of the present invention include: adding chlorine or bromine into a reactor, adjusting to the reaction temperature, and then slowly adding E-1-chloro-3,3,3-propene into the reactor until the reaction solution turns light yellow, and the reaction ends.

[0043] The specific operation steps of step (2) of the present invention include: sequentially adding a first solvent and a base into a reactor, adjusting to the reaction temperature, and then dropping a compound of formula (I) into the reactor for reaction to obtain a compound of formula (II) and / or formula (III).

[0044] The specific operation steps of step (3) of the present invention include: sequentially adding a second solvent, a reducing agent (and / or an initiator and / or an additive), and a compound of formula (II) and / or formula (III) into a reactor, adjusting to the reaction temperature, and after the reaction is initiated, continuously dropping a compound of formula (II) and / or formula (III) for reaction to obtain 3,3,3-trifluoro-1-propyne shown in formula (IV).

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] 1. The present invention firstly proposes a method for obtaining 3,3,3-trifluoro-1-propyne through an addition reaction and two-step dehalogenation elimination reactions using E-1233zd as a raw material. The method not only has simple and easily available raw materials, low production costs, simple reaction operations, high product yields, but also can realize solvent recycling to reduce three wastes and bromine recycling during the reaction process. The entire process is safe, environmentally friendly, has low production costs, and high feasibility for industrial application.

[0047] 2. The present invention introduces an additive during the elimination process in step (3), which can inhibit the self-polymerization of the product and significantly improve the product yield. Specific Embodiments

[0048] 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, improved, and equivalent solutions that may be included within the scope of the claims.

[0049] Example 1

[0050] This embodiment provides a method for preparing 3,3,3-trifluoro-1-propyne, which specifically includes the following steps:

[0051] (I) Addition reaction step (chlorine and E-1233zd)

[0052] A 500 mL high-pressure reactor made of inconel600 is used. A magnetic rotor is added to the reactor, and then it is evacuated with a vacuum water pump to a vacuum degree of -0.07 MPa. The reactor body is placed in a -20°C coolant for 30 minutes, and then 101.2 g (1.43 mol) of chlorine gas and 130 g (1 mol) of liquid-phase E-1233zd are charged. After the reactor body returns to room temperature, magnetic stirring and heating are started. When the temperature reaches 60°C, the reaction continues for 6 hours and then ends.

[0053] After the reactor is cooled to room temperature, the unreacted chlorine gas in the reactor is slowly introduced into the lye. When no bubbles emerge, it is replaced with nitrogen three times, and then the reactor can be opened to process the reaction solution. The reaction solution is washed with 5% sodium hydroxide solution until the pH of the reaction solution reaches 7, and then washed three times with 500 mL of water to obtain 201 g of a colorless liquid. Through gas chromatography analysis, the results show that the content of 1,1,2-trichloro-3,3,3-trifluoropropane (HCFC-233da) is 94.7%, the content of other impurities is 5.3%, and the reaction yield is calculated to be 94.7%.

[0054] (II) Lye elimination reaction step

[0055] A 1 L three-necked flask is used as the reactor. One neck is for feeding, one is for temperature measurement, and one is connected to a spherical condenser. The cooling medium is 20°C water.

[0056] A magnetic rotor, 500 mL of water, and 48 g (1.2 mol) of sodium hydroxide are successively added to the flask. The reaction solution is heated to 60°C under magnetic stirring, and then the 1,1,2-trichloro-3,3,3-trifluoropropane prepared in the previous step is added. The feeding rate is 120 g / hour, and the feeding is completed in about 1.5 hours, with a total feeding of 201 g (1 mol). The reaction continues for 2 hours. After the reaction ends, the lower organic phase is taken and washed three times with 500 mL of distilled water to obtain 163.4 g of a colorless and transparent liquid.

[0057] Through gas chromatography analysis of this colorless and transparent liquid, the results show that the content of 1,2-dichloro-3,3,3-trifluoropropene is 98.4%, the content of 1,1,2-trichloro-3,3,3-trifluoropropane is 0.3%, and the content of other impurities is 1.3%. The reaction yield is calculated to be 97.4%.

[0058] (III) Active metal elimination reaction step

[0059] The reactor also uses a 1L three-necked flask, one of which is the feeding port, one is the temperature measuring port, and one is the discharging port. The discharging port is connected to a spherical condenser. The condensate temperature is -20°C. The rear end of the condenser receives a collecting cylinder, and the cylinder is placed in a -60°C refrigerator.

[0060] In a nitrogen atmosphere, add a magnetic rotor, 78g (1.2mol) of zinc powder, 150g of DMF, 0.25g (0.0019mol) of I2, and 16.5g of 1,2-dichloro-3,3,3-trifluoropropene prepared in the above steps to the flask in turn, slowly raise the temperature to 90°C, and continue to add 1,2-dichloro-3,3,3-trifluoropropene after the reaction is initiated. The feeding rate is about 70g / h, and the time is 2h. The total feeding amount is 165g (1mol). After the feeding is completed, continue stirring for 1h, and the reaction is completed. The total weight of the material received in the steel cylinder is 70.5g. The gas in the steel cylinder is taken for gas chromatography analysis. The results show that the content of 1,1,1-trifluoropropyne is 99.6%, and the content of other substances is 0.4%. The calculated reaction yield is 74.7%.

[0061] Example 2

[0062] This embodiment provides a method for preparing 3,3,3-trifluoro-1-propyne, which specifically comprises the following steps:

[0063] (I) Addition reaction step (liquid bromine and E-1233zd)

[0064] The reactor uses a 1L three-necked flask, one of which is equipped with a thermometer, one is for the raw material inlet, and one is connected to a spherical condenser. The cooling medium is 5°C water. The top of the spherical condenser is connected to the tail gas absorption alkali solution through a catheter. The alkali solution is a 10% sodium hydroxide aqueous solution.

[0065] A magnetic rotor and 160 g (1 mol) of liquid bromine were added to a three-necked flask in sequence, and magnetic stirring and heating were started. When the temperature in the flask reached 40°C, gaseous E-1233zd was introduced. When the color of the reaction liquid changed from dark brown to light yellow, the introduction of E-1233zd was stopped. At this time, the amount of E-1233zd introduced was 135 g (1.04 mol). After continuing stirring for 30 minutes, the temperature was raised to 80°C, and stirring was continued for 30 minutes. The reaction was terminated.

[0066] After the reaction liquid was cooled to room temperature, 200 mL of 5% sodium bicarbonate solution was added to the reaction liquid. After sufficient stirring, the organic phase was filtered and washed three times with 500 mL of water to obtain 289.3 g of a light yellow product. The results of gas chromatography analysis showed that the content of 1,2-dibromo-1-chloro-3,3,3-trifluoropropane was 99.5%, the content of E-1233zd was 0.2%, and the content of other impurities was 0.3%. The reaction yield was calculated to be 99.3%.

[0067] (2) Alkaline solution elimination reaction steps

[0068] The reactor used is a 1L three-necked flask. One neck is for feeding, one is for temperature measurement, and one is connected to a spherical condenser. The cooling medium is water at 20°C.

[0069] A magnetic rotor, 500 mL of water, and 60 g (1.5 mol) of sodium hydroxide are successively added into the flask. The reaction solution is heated to 60°C under magnetic stirring, and then 1,2-dibromo-1-chloro-3,3,3-trifluoropropane prepared in the previous step is added. The feeding rate is 120 g / h, and the feeding is completed in about 2.5 hours. The total feeding amount is 290 g (1 mol). The reaction continues for 2 hours. After the reaction ends, the lower organic phase is taken and washed three times with 500 mL of distilled water to obtain 225.4 g of a colorless transparent liquid.

[0070] Gas chromatography analysis of the above colorless transparent liquid shows that the content of 2-bromo-1-chloro-3,3,3-trifluoropropene is 48.46%, the content of 1,2-dibromo-3,3,3-trifluoropropene is 47.58%, and the content of others is 3.96%. The total reaction yield is calculated to be 94.5%.

[0071] (3) Active metal elimination reaction steps

[0072] The reactor also uses a 1L three-necked flask. One neck is for feeding, one is for temperature measurement, and one is for discharging. The discharging port is connected to a spherical condenser, the temperature of the condensate is -20°C, and the rear end of the condenser is connected to a collecting steel cylinder, which is placed in a refrigerator at -60°C.

[0073] In a nitrogen atmosphere, a magnetic rotor, 143 g (2.2 mol) of zinc powder, 150 g of DMF, 0.25 g (0.0019 mol) of I2, and a mixture of 25 g of 2-bromo-1-chloro-3,3,3-trifluoropropene and 1,2-dibromo-3,3,3-trifluoropropene prepared in the previous step are successively added into the flask. The temperature is slowly raised to 70°C. When the reaction is initiated, the mixture of 2-bromo-1-chloro-3,3,3-trifluoropropene and 1,2-dibromo-3,3,3-trifluoropropene is continuously added. The feeding rate is about 70 g / h, and it takes 3 hours. The total feeding amount is 230 g. After the feeding is completed, stirring continues for 1 hour. The reaction ends, and the total weight of the materials received in the steel cylinder is 76.3 g. Gas chromatography analysis of the gas in the steel cylinder shows that the content of 1,1,1-trifluoropropyne is 99.5%, and the content of others is 0.4%. The reaction yield is calculated to be 83.8%.

[0074] Example 3

[0075] The operation of this example is the same as that of Example 1, except that in the alkaline solution elimination reaction step, 134 g (1.2 mol) of potassium tert-butoxide is used instead of sodium hydroxide as the base, and the solvent is changed to isopropanol, and other operations remain unchanged.

[0076] After the reaction was completed, 162.9 g of a colorless and transparent liquid was collected. Gas chromatography analysis of this colorless and transparent liquid showed that the content of 1,2-dichloro-3,3,3-trifluoropropene was 96.8%, the content of 1,1,2-trichloro-3,3,3-trifluoropropane was 1.4%, and the content of other substances was 1.8%. The reaction yield was calculated to be 95.6%.

[0077] Example 4

[0078] The operation of this example was the same as that of Example 1, except that: in the alkali elimination reaction step, 47 g (1.2 mol) of sodium amide was used instead of sodium hydroxide as the alkali, and the first solvent was changed to 500 mL of dry tetrahydrofuran. The operation steps were as follows:

[0079] Sodium amide was slowly added to the tetrahydrofuran containing 201 g (1 mol) of 1,1,2-trichloro-3,3,3-trifluoropropane, and the reaction temperature was controlled at -20°C. After the addition of sodium amide was completed, the reaction continued for 2 h, and then dilute hydrochloric acid was slowly added dropwise at this temperature to quench the reaction. The fraction at 54 - 60°C was collected by distillation to obtain 151.3 g of a colorless and transparent liquid. Gas chromatography analysis of this colorless and transparent liquid showed that the content of 1,2-dichloro-3,3,3-trifluoropropene was 93.8%, the content of 1,1,2-trichloro-3,3,3-trifluoropropane was 0.2%, the content of tetrahydrofuran was 2.3%, and the content of other substances was 3.7%. The reaction yield was calculated to be 86.0%.

[0080] Example 5

[0081] The operation of this example was the same as that of Example 1, except that: in the alkali elimination reaction step, 500 mL of methanol was used instead of water as the first solvent, and other operations remained unchanged. After the reaction was completed, 163.1 g of a colorless and transparent liquid was collected. Gas chromatography analysis of this colorless and transparent liquid showed that the content of 1,2-dichloro-3,3,3-trifluoropropene was 98.3%, the content of 1,1,2-trichloro-3,3,3-trifluoropropane was 0.3%, and the content of other substances was 1.4%. The reaction yield was calculated to be 97.2%.

[0082] Example 6

[0083] The operation of this example is the same as that of Example 1, with the only difference being that in the lye elimination reaction step, the amount of potassium hydroxide used is increased to 112 g (2.0 mol), and other operations remain unchanged. After the reaction is completed, 163.50 g of a colorless and transparent liquid is collected. Gas chromatography analysis of this colorless and transparent liquid shows that the content of 1,2-dichloro-3,3,3-trifluoropropene is 98.9%, the content of 1,1,2-trichloro-3,3,3-trifluoropropane is 0.1%, and the content of others is 1.0%. The reaction yield is calculated to be 98.0%.

[0084] Example 7

[0085] The operation of this example is the same as that of Example 1, with the only difference being that in the lye elimination reaction step, the reaction temperature is lowered to 30 °C, and other operations remain unchanged. After the reaction is completed, 181.2 g of a colorless and transparent liquid is collected. Gas chromatography analysis of this colorless and transparent liquid shows that the content of 1,2-dichloro-3,3,3-trifluoropropene is 44.8%, the content of 1,1,2-trichloro-3,3,3-trifluoropropane is 53.1%, and the content of others is 2.1%. The reaction yield is calculated to be 49.2%.

[0086] Example 8

[0087] The operation of this example is the same as that of Example 7, with the only difference being that in the lye elimination reaction step, the reaction continues for 6 h after the feeding is completed, and other operations remain unchanged. After the reaction is completed, 168.2 g of a colorless and transparent liquid is collected. Gas chromatography analysis of this colorless and transparent liquid shows that the content of 1,2-dichloro-3,3,3-trifluoropropene is 95.2%, the content of 1,1,2-trichloro-3,3,3-trifluoropropane is 3.3%, and the content of others is 1.5%. The reaction yield is 97.0%.

[0088] Example 9

[0089] The operation of this example is the same as that of Example 1, with the only difference being that in the lye elimination reaction step, the reaction temperature is changed to 100 °C, and other operations remain unchanged. After the reaction is completed, 158.3 g of a colorless and transparent liquid is collected. Gas chromatography analysis of this colorless and transparent liquid shows that the content of 1,2-dichloro-3,3,3-trifluoropropene is 96.6%, the content of 1,1,2-trichloro-3,3,3-trifluoropropane is 0.1%, and the content of others is 3.3%. The reaction yield is 92.7%.

[0090] Example 10

[0091] The operation of this example is the same as that of Example 1, except that: in the active metal elimination reaction step, the amount of zinc powder is increased to 130 g (2 mol). After the reaction, the total weight of the materials received in the steel cylinder is 86.5 g. The gas in the steel cylinder is taken for gas chromatography analysis. The results show that the content of 1,1,1-trifluoropropyne is 99.6%, and the other content is 0.4%. The reaction yield is calculated to be 91.7%.

[0092] Example 11

[0093] The operation of this example is the same as that of Example 10, except that: in the active metal elimination reaction step, the second solvent uses isopropanol instead of DMF, and the dosage remains unchanged. After the reaction, the total weight of the materials received in the steel cylinder is 85.0 g. The gas in the steel cylinder is taken for gas chromatography analysis. The results show that the content of 1,1,1-trifluoropropyne is 99.5%, and the other content is 0.5%. The reaction yield is calculated to be 90.0%.

[0094] Example 12

[0095] The operation of this example is the same as that of Example 10, except that: in the active metal elimination reaction step, the initiator uses 1.4 g of zinc chloride instead of I2. After the reaction, the total weight of the materials received in the steel cylinder is 65.0 g. The gas in the steel cylinder is taken for gas chromatography analysis. The results show that the content of 1,1,1-trifluoropropyne is 99.5%, and the other content is 0.5%. The reaction yield is calculated to be 68.8%.

[0096] Example 13

[0097] The operation of this example is the same as that of Example 10, except that: in the active metal elimination reaction step, 48 g of magnesium chips are used instead of zinc powder, and the solvent is changed to 330 g of dry tetrahydrofuran instead of DMF, and the reaction temperature is reduced to 80 °C. After the reaction, the total weight of the materials received in the steel cylinder is 83.6 g. The gas in the steel cylinder is taken for gas chromatography analysis. The results show that the content of 1,1,1-trifluoropropyne is 99.0%, and the other content is 1%. The reaction yield is calculated to be 88.0%.

[0098] Example 14

[0099] The operation of this example is the same as that of Example 10, except that: in the active metal elimination reaction step, the reaction temperature is increased to 110 °C. After the reaction, the total weight of the materials received in the steel cylinder is 75.4 g. The gas in the steel cylinder is taken for gas chromatography analysis. The results show that the content of 1,1,1-trifluoropropyne is 99.6%, and the other content is 0.4%. The reaction yield is calculated to be 79.9%.

[0100] Example 15

[0101] The operation of this example is the same as that of Example 10, except that: no initiator is added. The reaction phenomenon is significantly different, and no obvious reaction initiation process is observed. After stirring at 90 °C for 3 h, the raw material of 1,2-dichloro-3,3,3-trifluoropropene is added.

[0102] After the reaction is completed, the total weight of the materials received in the steel cylinder is 18.8 g. The gas in the steel cylinder is taken for gas chromatography analysis. The results show that the content of 1,1,1-trifluoropropyne is 99.5%, and the other content is 0.5%. The reaction yield is calculated to be 19.9%.

[0103] Example 16

[0104] The operation of this example is the same as that of Example 10, except that: the additive 4-methoxyphenol is added, and the dosage is 0.62 g (0.005 mol).

[0105] After the reaction is completed, the total weight of the materials received in the steel cylinder is 89.8 g. The gas in the steel cylinder is taken for gas chromatography analysis. The results show that the content of 1,1,1-trifluoropropyne is 99.6%, and the other content is 0.4%. The reaction yield is calculated to be 95.3%.

[0106] Example 17

[0107] The operation of this example is the same as that of Example 10, except that: the additive p-phenylenediamine is added, and the dosage is 0.54 g (0.005 mol).

[0108] After the reaction is completed, the total weight of the materials received in the steel cylinder is 90.6 g. The gas in the steel cylinder is taken for gas chromatography analysis. The results show that the content of 1,1,1-trifluoropropyne is 99.6%, and the other content is 0.4%. The reaction yield is calculated to be 96.0%.

[0109] Comparative Example 1

[0110] The reactor uses a 1 L three-necked flask. One neck is equipped with a thermometer, one neck is the raw material inlet, and one neck is connected to a spherical condenser. The cooling medium is water at 25 °C. The top of the spherical condenser is connected to a metal bottle through a conduit to collect the product, and the metal bottle is placed in a -60 °C freezer.

[0111] In a nitrogen atmosphere, a magnetic rotor, 500 mL of water, and 168 g (3 mol) of potassium hydroxide are added to the flask in sequence. The reaction solution is heated to 80 °C under magnetic stirring, and then trans-1-chloro-3,3,3-trifluoropropene is added dropwise at a feeding rate of 60 g / h. The feeding is completed in about 2 h, with a total feeding of 130 g (1 mol). The reaction continues for 4 h and then ends.

[0112] After the reaction was completed, the total weight of the materials collected in the steel cylinder was 126 g. Sampling and analysis showed that the content of trans-1-chloro-3,3,3-trifluoropropene was 98.6%, and the other was 1.4%. 1,1,1-Trifluoropropyne was not detected, indicating that the reaction hardly occurred.

[0113] The present invention uses a three-step reaction method to convert inexpensive E-1233zd into 3,3,3-trifluoropropyne, solving the problems of difficult access to raw materials and low reaction yield in traditional processes. The raw materials used are all inexpensive and readily available industrial raw materials. By introducing additives in the reaction, self-polymerization of the product is reduced, the reaction yield is increased, and the feasibility of industrial implementation is higher.

Claims

1. A method for preparing 3,3,3-trifluoro-1-propyne, characterized in that: The preparation method includes: (1) Using E-1-chloro-3,3,3-trifluoropropene as a raw material, adding chlorine or bromine to obtain the compound shown by the following formula (I); (2) In a first solvent and in the presence of a base, the compound shown by formula (I) undergoes an elimination reaction to obtain 1,2-dichloro-3,3,3-trifluoropropene shown by the following formula (II) and / or 2-chloro-1-chloro-3,3,3-trifluoropropene shown by the following formula (III); (3) In a second solvent and in the presence of a reducing agent, the compound shown by formula (II) and / or formula (III) undergoes an elimination reaction to obtain 3,3,3-trifluoro-1-propyne shown by formula (IV); The reaction equations are as follows: In the formula, X is chlorine or bromine. When X is chlorine, the structures of the compounds of formula (II) and (III) are the same and are 1,2-dichloro-3,3,3-trifluoropropene.

2. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 1, characterized in that: In step (2), the base is selected from at least one of alkali metal hydroxides, alkali metal alcoholates, and alkali metal amides.

3. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 1, wherein: In step (2), the first solvent is selected from at least one of water, alcohol solvents, ether solvents, nitrile solvents, amide solvents, or sulfone solvents; the alcohol solvents are selected from at least one of methanol, ethanol, propanol, isopropanol, ethylene glycol, or diethylene glycol; the ether solvents are selected from at least one of tetrahydrofuran, diethyl ether, or dioxane; the nitrile solvents are selected from at least one of acetonitrile, propionitrile, or butyronitrile; the amide solvents are selected from at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), or hexamethylphosphoric triamide (HMPA); the sulfone solvents are selected from at least one of dimethyl sulfoxide (DMSO) and / or sulfolane.

4. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 2, characterized in that: In step (2), the molar ratio of the compound shown by formula (I) to the base is 1:(1 - 5).

5. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 3, characterized in that: In step (2), the mass ratio of the compound shown by formula (I) to the first solvent is 1:(1 - 5).

6. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 1, characterized in that: In step (3), the reducing agent is selected from at least one of zinc powder, magnesium chips, or iron powder.

7. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 1, characterized in that: In step (3), the reaction is carried out in the presence of an initiator, and the initiator is selected from zinc chloride, 1,2-dibromoethane, Br2, I2, hydrochloric acid, propionic acid, or oxalic acid.

8. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 1, characterized in that: In step (3), the reaction is carried out in the presence of an additive, and the additive is selected from one of phenolic compounds, quinone compounds, aromatic amine compounds, phenylhydrazine compounds, ferric chloride, sodium sulfide, ammonium thiocyanate, or cuprous oxide.

9. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 8, characterized in that: The phenolic compounds are selected from at least one of phenol, p-dihydroxybenzene, 4-methoxyphenol, 4-tert-butyl-2,6-dimethylphenol, 4,4'-dihydroxybiphenyl, or bisphenol A; The quinone compounds are selected from at least one of tetrachlorobenzoquinone, p-benzoquinone, or 1,4-naphthoquinone; The aromatic amine compounds are selected from at least one of 4-methylaniline, diphenylamine, benzidine, p-phenylenediamine, or N-nitrosodiphenylamine; The phenylhydrazine compounds are selected from at least one of 1,1-diphenyl-2-trinitrophenylhydrazine or N,N-diphenyl-N-2,4,6-trinitrophenylhydrazine.

10. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 1, wherein: In step (3), the second solvent is selected from at least one of methanol, ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol, tetrahydrofuran, diethyl ether, dioxane, acetonitrile, propionitrile, butyronitrile, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), hexamethylphosphoric triamide (HMPA), dimethyl sulfoxide (DMSO), sulfolane, etc.

11. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 1, wherein: In step (3), the molar ratio of the compound represented by formula (II) and / or formula (III) to the reducing agent is 1:(1-5).

12. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 7, wherein: In step (3), the molar ratio of the compound represented by formula (II) and / or formula (III) to the initiator is 1:(0.01%-1%).

13. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 8, characterized in that: In step (3), the molar ratio of the compound represented by formula (II) and / or formula (III) to the additive is 1:(0.1%-1%).

14. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 1, characterized in that: In step (3), the mass ratio of the compound represented by formula (II) and / or formula (III) to the second solvent is 1:(1-5).

15. The method for preparing 3,3,3-trifluoro-1-propyne according to claim 1, wherein: In step (1), the reaction temperature is -5 to 100 °C and the reaction time is 1 to 10 h; In step (2), the reaction temperature is -20 to 120 °C and the reaction time is 2 to 4 h; In step (3), the reaction temperature is 25 to 140 °C and the reaction time is 2 to 6 h.

16. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 1, characterized in that: Step (1) specifically includes: adding chlorine or bromine into the reactor, adjusting to the reaction temperature, and then slowly adding E-1-chloro-3,3,3-propene into the reactor until the reaction solution turns light yellow, and the reaction ends.

17. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 1, characterized in that: Step (2) specifically includes: sequentially adding the first solvent and the base into the reactor, adjusting to the reaction temperature, and then dropping the compound of formula (I) into the reactor for reaction to obtain the compound of formula (II) and / or formula (III).

18. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 1, characterized in that: Step (3) specifically includes: sequentially adding the second solvent, the reducing agent, and the compound of formula (II) and / or formula (III) into the reactor, adjusting to the reaction temperature, and after the reaction is initiated, continuously dropping the compound of formula (II) and / or formula (III) for reaction to obtain 3,3,3-trifluoro-1-propyne represented by formula (IV).

19. The preparation method of 3,3,3-trifluoro-1-propyne according to claim 18, characterized in that: In step (3), the initiator and / or the additive are added into the reactor together with the reducing agent.

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