Process for the preparation of 3,3,3-trifluoropropanal from chlorotrifluoromethane

Abstract

The application belongs to the technical field of fluorine-containing chemicals, and particularly relates to a method for preparing 3,3,3-trifluoropropionaldehyde from chlorotrifluoromethane. The method for preparing 3,3,3-trifluoropropionaldehyde from chlorotrifluoromethane comprises the following steps: adding zinc powder into a solvent, adding an initiator, heating to 60-80 DEG C, sealing reaction, introducing chlorotrifluoromethane, continuing reaction, obtaining a reaction solution containing trifluoromethyl organic zinc; adding the reaction solution into a 2-chloro-oxirane solution at 0-5 DEG C, keeping reaction, adjusting pH to 5-6, quenching, obtaining 3,3,3-trifluoropropionaldehyde crude product, and obtaining pure product through rectification. The method for preparing 3,3,3-trifluoropropionaldehyde from chlorotrifluoromethane is easy to obtain raw materials, stable in process, high in yield and low in cost.

Description

Technical Field

[0001] This invention belongs to the field of fluorine-containing chemical preparation technology, specifically relating to a method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane. Background Technology

[0002] 3,3,3-Trifluoropropanal (molecular formula CF3CH2CHO, molecular weight 112.05, CAS number: 460-40-2) is a key class of fluorinated fine chemicals and core organic synthesis intermediates, widely used in pharmaceuticals, pesticides and high-performance fluoropolymers. It can be further derived to prepare high-value-added fluorinated chemicals such as trifluoropropionic acid, trifluoropropionic acid ester, trifluoropropanol, trifluoropropanal oxime, and trifluoropropionyl chloride, and occupies an important position in the fluorinated aliphatic compound system.

[0003] Early methods for synthesizing 3,3,3-trifluoropropane mainly included the trifluoropropyne method and the trifluoropropanol oxidation method. Among them, the trifluoropropyne method requires the use of highly toxic catalysts such as mercury salts, which poses significant environmental hazards and high safety risks; the trifluoropropanol oxidation method not only has scarce raw material sources and high preparation costs, but also relies on toxic oxidants such as sodium dichromate, resulting in poor atom economy and serious pollution from waste.

[0004] The current mainstream industrialization route uses trifluoropropylene and its derivatives as raw materials, mainly divided into two categories: one is to use 1-chloro-3,3,3-trifluoropropylene as a starting material, and prepare the target product through multiple steps of reaction such as substitution, addition, and acid hydrolysis; the other is to use 3,3,3-trifluoropropylene methyl ether or 1,1-dialkoxy-3,3,3 Using trifluoropropane as a raw material, 3,3,3-trifluoropropaldehyde is converted to 3,3,3-trifluoropropane via acid-catalyzed hydrolysis / alcohololysis. For example, CN101277917A discloses the reaction of 1-chloro-3,3,3-trifluoropropene with a chain alcohol to generate a vinyl ether, followed by acidic hydrolysis to obtain 3,3,3-trifluoropropaldehyde. However, the hydrolysis process easily generates acetal byproducts, resulting in a target product yield of less than 50%. CN105669399A uses 1,1-dialkoxy-3,3,3-trifluoropropane as a raw material to prepare 3,3,3-trifluoropropaldehyde under the action of acetic acid and an acid catalyst, achieving a yield of over 95%. However, this method still relies on a dedicated fluorinated acetal raw material, resulting in high supply chain costs and limited raw material supply. CN102010307A uses solid superacid catalysis to react 3,3,3-trifluoropropene methyl ether with valeric acid, achieving a yield of over 95%. The catalyst can be recycled, but the high price of the core raw material, 3,3,3-trifluoropropene methyl ether, restricts the economic efficiency of the process. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane, which has readily available raw materials, stable process, high yield and low cost.

[0006] The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to the present invention includes the following steps: (1) Preparation of organozinc reagent: Add zinc powder to solvent, add initiator, heat to 60~80℃ and seal the reaction, introduce chlorotrifluoromethane and continue the reaction to obtain a reaction solution containing trifluoromethyl organozinc. (2) Addition and hydrolysis elimination: The reaction solution obtained in step (1) is added to a 2-chloroethylene oxide solution at 0~5℃, and the reaction is kept at the temperature. The pH is adjusted to 5~6 and quenched to obtain crude 3,3,3-trifluoropropaldehyde. Pure 3,3,3-trifluoropropaldehyde is obtained by distillation.

[0007] The molar ratio of zinc powder to 2-chloroethylene oxide is 1.3:1 to 1.5:1.

[0008] The molar ratio of the initiator to 2-chloroethylene oxide is 1:20 to 1:50.

[0009] The zinc powder mentioned in step (1) is zinc powder activated with an activator, which is hydrochloric acid solution, trimethylchlorosilane, or sulfuric acid solution. The activator is a 1 mol / L hydrochloric acid solution, trimethylchlorosilane, and a 5 wt% sulfuric acid solution.

[0010] The 2-chloroethylene oxide solution mentioned in step (2) is a solution in which 2-chloroethylene oxide is dissolved in a solvent. The solvent here is also tetrahydrofuran, toluene, 1,4-dioxane, or diethylene glycol dimethyl ether.

[0011] The solvent in step (1) is tetrahydrofuran, toluene, 1,4-dioxane or diethylene glycol dimethyl ether, and the solvent is an ultra-dry solvent with a moisture content of less than 5 ppm.

[0012] The initiator in step (1) is iodine, 1,2-dibromoethane or ethyl magnesium chloride.

[0013] After introducing chlorotrifluoromethane in step (1), the reaction pressure is 3~5 bar, the temperature is 60~80℃, and the reaction time is 8~12 h.

[0014] Step (2) Adjust the pH using hydrochloric acid or sulfuric acid solution with a concentration of 2 mol / L to 5 mol / L.

[0015] The reaction temperature for quenching in step (2) is 30~40℃, and the reaction time is 1~2h.

[0016] The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to the present invention has the following reaction mechanism: .

[0017] Specifically, the method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane includes the following steps: (1) Preparation of organozinc reagent: Add solvent to stainless steel reaction vessel with pressure gauge, then add activated zinc powder and initiator, then purge with nitrogen three times, heat to 60~80℃ and seal the reaction, purge with chlorotrifluoromethane, maintain temperature and pressure at 3~5 bar and stir the reaction for 8~12h, stop stirring when the reaction is finished, cool the temperature inside the reaction vessel to room temperature through external condenser, and transfer excess chlorotrifluoromethane to another gas tank for recovery to obtain reaction solution containing trifluoromethyl organozinc, which is stored under nitrogen atmosphere for later use; (2) Addition and hydrolysis elimination: The reaction solution obtained in step (1) is slowly added to a Schlenk tube with nitrogen protection at 0~5℃. A solvent solution of 2-chloroethylene oxide is added to the Schlenk tube, stirred and kept warm for 30min~60min, then raised to room temperature, and 2mol / L~5mol / L hydrochloric acid solution or sulfuric acid solution is added to adjust the pH to 5~6. The temperature is raised to 30~40℃ and stirred for 1~2h to quench the reaction, and crude 3,3,3-trifluoropropaldehyde is obtained. Pure 3,3,3-trifluoropropaldehyde is obtained by atmospheric distillation.

[0018] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention is the first to prepare 3,3,3-methyl groups using industrial by-product chlorotrifluoromethane as a trifluoromethyl source. Trifluoropropionaldehyde enables the high-value utilization of waste fluorine-containing resources, significantly reduces raw material costs, and significantly improves atom economy.

[0019] (2) The reaction route of this invention is short, the conditions are mild and the operation is safe. It does not require high temperature and high pressure or highly toxic catalysts, avoids the use of toxic materials such as mercury salts and dichromates, and has low emissions of waste, making it a green and environmentally friendly product.

[0020] (3) The target product of this invention has a high yield, good purity, and is easy to industrialize. It can be obtained in two steps. Trifluoropropionaldehyde has a purity of ≥99%, a yield of over 85%, strong process stability, and is suitable for continuous large-scale production. Attached Figure Description

[0021] Figure 1 The gas chromatogram of 3,3,3-trifluoropropionaldehyde prepared in Example 1 is shown.

[0022] Figure 2 The chromatogram is for the 3,3,3-trifluoropropionaldehyde standard sample. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments.

[0024] All solvents used below are ultra-dry solvents with a water content of less than 5 ppm. The room temperature described in this invention is 20~25℃.

[0025] The chlorotrifluoromethane is a byproduct of the preparation of trifluorochloroethylene and tetrafluoroethylene, with a purity of 99%.

[0026] The zinc powder used below has been activated. The activation steps are as follows: the zinc powder is rinsed multiple times with a 1 mol / L hydrochloric acid solution until it has a metallic luster, and then dried in a vacuum drying oven at 40-60℃ until the moisture content is less than 2 ppm.

[0027] The following purities were determined by GC chromatography, and the yields were based on 2-chloroethylene oxide.

[0028] Example 1 The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to the present invention includes the following steps: (1) Preparation of organozinc reagent: Add 200 mL of tetrahydrofuran to a stainless steel reactor equipped with a pressure gauge, then add 0.751 mol of zinc powder and 0.017 mol of iodine initiator, then purge with nitrogen three times, heat to 70 °C and seal the reaction, purge with chlorotrifluoromethane, maintain the temperature, maintain the pressure at 4 bar and stir the reaction for 9 h, stop stirring when the reaction is finished, cool the temperature inside the reactor to room temperature through an external condenser, and transfer the excess chlorotrifluoromethane to another gas tank for recovery, and obtain a reaction solution containing trifluoromethyl organozinc, which is stored under a nitrogen atmosphere for later use; (2) Addition and hydrolysis elimination: The reaction solution obtained in step (1) was cooled to 2°C and slowly added to a Schlenk tube under nitrogen protection. A solution of 0.556 mol / L tetrahydrofuran (200 mL) of 2-chloroethylene oxide was added to the Schlenk tube, stirred, and kept at 2°C for 45 min. Then, the temperature was raised to room temperature, and 3 mol / L hydrochloric acid solution was added to adjust the pH to 5-6. The reaction was quenched by stirring at 35°C for 1.5 h to obtain crude 3,3,3-trifluoropropionaldehyde. The pure product was obtained by atmospheric distillation. The purity was found to be 99.5%. Figure 1 As shown, the calculated yield is 91%. Figure 2 The chromatogram of the 3,3,3-trifluoropropionaldehyde standard sample is shown below. The chromatogram of the product prepared in this invention is shown below. Figure 2 The comparison shows that the main retention time of the sample prepared by this invention is highly consistent with that of the standard, and the main product can be qualitatively confirmed as 3,3,3-trifluoropropionaldehyde.

[0029] Example 2 The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to the present invention includes the following steps: (1) Preparation of organozinc reagent: Add 200 mL of tetrahydrofuran to a stainless steel reactor equipped with a pressure gauge, then add 0.752 mol of zinc powder and 0.012 mol of 1,2-dibromoethane initiator. Then purge with nitrogen three times, heat to 60 °C and seal the reaction. Purge with chlorotrifluoromethane, maintain the temperature, and keep the pressure at 5 bar while stirring for 8 hours. Stop stirring when the reaction is finished. Cool the temperature inside the reactor to room temperature through an external condenser. Transfer the excess chlorotrifluoromethane to another gas tank for recovery. Obtain the reaction solution containing trifluoromethyl organozinc and store it under a nitrogen atmosphere for later use. (2) Addition and hydrolysis elimination: The reaction solution obtained in step (1) was cooled to 0°C and slowly added to a Schlenk tube under nitrogen protection. A solution of 0.578 mol 2-chloroethylene oxide in tetrahydrofuran (200 mL) was added to the Schlenk tube, stirred, and kept at 0°C for 50 min. Then, the temperature was raised to room temperature, and 2 mol / L hydrochloric acid solution was added to adjust the pH to 5-6. The mixture was then heated to 30°C and stirred for 1 h to quench the reaction, yielding crude 3,3,3-trifluoropropionaldehyde. The purified product was obtained by atmospheric distillation. The purity was 99.1%, and the calculated yield was 87%.

[0030] Example 3 The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to the present invention includes the following steps: (1) Preparation of organozinc reagent: Add 200 mL of toluene to a stainless steel reactor equipped with a pressure gauge, then add 0.75 mol of zinc powder and 0.025 mol of ethyl magnesium chloride initiator. Then purge with nitrogen three times, heat to 80 °C and seal the reactor. Purge with chlorotrifluoromethane, maintain the temperature, and keep the pressure at 3 bar while stirring for 12 h. Stop stirring when the reaction is finished. Cool the temperature inside the reactor to room temperature through an external condenser. Transfer the excess chlorotrifluoromethane to another gas tank for recovery. The reaction solution containing trifluoromethyl organozinc is obtained and stored under a nitrogen atmosphere for later use. (2) Addition and hydrolysis elimination: The reaction solution obtained in step (1) was cooled to 5°C and slowly added to a Schlenk tube under nitrogen protection. A 0.5 mol / L toluene (200 mL) solution of 2-chloroethylene oxide was added to the Schlenk tube, stirred, and kept at 5°C for 30 min. Then, the temperature was raised to room temperature, and 5 mol / L hydrochloric acid solution was added to adjust the pH to 5-6. The mixture was then heated to 40°C and stirred for 2 h to quench the reaction, yielding crude 3,3,3-trifluoropropionaldehyde. The purified product was obtained by atmospheric distillation. The purity was 99.25%, and the calculated yield was 85%.

[0031] Example 4 The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to the present invention includes the following steps: (1) Preparation of organozinc reagent: 200 mL of 1,4-dioxane solvent was added to a stainless steel reactor equipped with a pressure gauge, followed by 0.753 mol of zinc powder and 0.019 mol of 1,2-dibromoethane initiator. Nitrogen gas was then introduced to replace the initiator three times. The temperature was raised to 65 °C and the reactor was sealed. Chlorotrifluoromethane was introduced to maintain the temperature and pressure at 3.5 bar. The reaction was stirred for 8 hours. After the reaction was completed, stirring was stopped. The temperature inside the reactor was cooled to room temperature through an external condenser. Excess chlorotrifluoromethane was transferred to another gas tank for recovery. The reaction solution containing trifluoromethyl organozinc was obtained and stored under a nitrogen atmosphere for later use. (2) Addition and hydrolysis elimination: The reaction solution obtained in step (1) was cooled to 3°C and slowly added to a Schlenk tube under nitrogen protection. A solution of 0.537 mol 2-chloroethylene oxide in 1,4-dioxane (200 mL) was added to the Schlenk tube. The mixture was stirred and kept at 3°C ​​for 60 min. Then, the temperature was raised to room temperature, and 2 mol / L sulfuric acid solution was added to adjust the pH to 5-6. The mixture was then heated to 35°C and stirred for 2 h to quench the reaction, yielding crude 3,3,3-trifluoropropanal. The crude product was obtained by atmospheric distillation. The purity was 99.4%, and the calculated yield was 89.5%.

[0032] Example 5 The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to the present invention includes the following steps: (1) Preparation of organozinc reagent: Add 200 mL of diethylene glycol dimethyl ether to a stainless steel reactor equipped with a pressure gauge, then add 0.751 mol of zinc powder and 0.014 mol of iodine initiator, then purge with nitrogen three times, heat to 75 °C and seal the reaction, purge with chlorotrifluoromethane, maintain the temperature, maintain the pressure at 3 bar and stir the reaction for 10 h, stop stirring when the reaction is finished, cool the temperature inside the reactor to room temperature through an external condenser, and transfer the excess chlorotrifluoromethane to another gas tank for recovery to obtain a reaction solution containing trifluoromethyl organozinc, which is stored under a nitrogen atmosphere for later use; (2) Addition and hydrolysis elimination: The reaction solution obtained in step (1) was cooled to 4°C and slowly added to a Schlenk tube under nitrogen protection. A solution of 0.556 mol 2-chloroethylene oxide in diethylene glycol dimethyl ether (200 mL) was added to the Schlenk tube. The mixture was stirred and kept at 4°C for 40 min. Then, the temperature was raised to room temperature, and 5 mol / L sulfuric acid solution was added to adjust the pH to 5-6. The mixture was then heated to 40°C and stirred for 1 h to quench the reaction, yielding crude 3,3,3-trifluoropropionaldehyde. The purified product was obtained by atmospheric distillation. The purity was 99.35%, and the calculated yield was 90.3%.

Claims

1. A method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane, characterized in that, Includes the following steps: (1) Preparation of organozinc reagent: Add zinc powder to solvent, add initiator, heat to 60~80℃ and seal the reaction, introduce chlorotrifluoromethane and continue the reaction to obtain a reaction solution containing trifluoromethyl organozinc. The initiator is iodine, 1,2-dibromoethane, or ethyl magnesium chloride; The zinc powder is zinc powder that has been pre-activated with an activator, such as hydrochloric acid solution, trimethylchlorosilane, or sulfuric acid solution. (2) Addition and hydrolysis elimination: The reaction solution obtained in step (1) is added to a 2-chloroethylene oxide solution at 0~5℃, and the reaction is kept at the temperature. The pH is adjusted to 5~6 and quenched to obtain crude 3,3,3-trifluoropropaldehyde. Pure 3,3,3-trifluoropropaldehyde is obtained by distillation.

2. The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to claim 1, characterized in that: The molar ratio of zinc powder to 2-chloroethylene oxide is 1.3:1 to 1.5:

1.

3. The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to claim 2, characterized in that: The molar ratio of the initiator to 2-chloroethylene oxide is 1:20 to 1:

50.

4. The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to claim 1, characterized in that: The 2-chloroethylene oxide solution in step (2) is a solution in which 2-chloroethylene oxide is dissolved in a solvent.

5. The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to claim 4, characterized in that: The solvent is tetrahydrofuran, toluene, 1,4-dioxane, or diethylene glycol dimethyl ether.

6. The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to claim 1, characterized in that: After introducing chlorotrifluoromethane in step (1), the reaction pressure is 3~5 bar, the temperature is 60~80℃, and the reaction time is 8~12 h.

7. The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to claim 1, characterized in that: Step (2) Adjust the pH using hydrochloric acid solution or sulfuric acid solution.

8. The method for preparing 3,3,3-trifluoropropane from chlorotrifluoromethane according to claim 1, characterized in that: The reaction temperature for quenching in step (2) is 30~40℃, and the reaction time is 1~2h.

Images