A continuous preparation method of 2,2,2-trifluoroethanol

Abstract

The present invention discloses a continuous preparation method of 2,2,2-trifluoroethanol, comprising: (1) adding KOH, water and γ-butyrolactone into a first reactor and a second reactor respectively, and obtaining a first intermediate product and a second intermediate product through hydrolysis reactions respectively; (2) preheating the first intermediate product and continuously introducing it into a high-pressure reactor simultaneously with 1,1,1-trifluoro-2-chloroethane and the second intermediate product for a nucleophilic reaction to obtain a reaction solution; (3) performing solid-liquid separation on the reaction solution, and respectively obtaining unreacted 1,1,1-trifluoro-2-chloroethane, bottom liquid and 2,2,2-trifluoroethanol product after rectifying the separated liquid phase. The present invention realizes the continuous preparation of 2,2,2-trifluoroethanol, has simple operation, low energy consumption, effectively improves the reaction efficiency and product production capacity; and the product quality is more stable; the rectification residue liquid can be continuously recycled without treatment, has high economy, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorine-containing fine chemicals, and particularly relates to a continuous preparation method of 2,2,2-trifluoroethanol. Background Art

[0002] 2,2,2-Trifluoroethanol, abbreviated as trifluoroethanol or TFEA, is an important aliphatic fluorine-containing intermediate. Trifluoroethanol can not only be used as an organic refrigerant, but also be an important raw material for synthesizing fluorine-containing compounds, and is widely used in the fields of fluorine-containing medicine, pesticide synthesis, high-grade solvents, dyes, and energy. It can be used to prepare anesthetics, gastric ulcer drugs, various pesticides, trifluoroacetic acid derivatives, fluorinated ether anesthetics, etc. As a basic fluorine-containing organic intermediate with high added value and good development prospects, it has a wide range of market applications.

[0003] For the synthesis of this compound, various methods have been proposed. The method of 1,1,1-trifluoro-2-chloroethane (CF3CH2Cl, abbreviated as R133a) has been studied deeply, mainly synthesized by batch method and industrialized.

[0004] For example, JP60120835 performs a high-pressure esterification reaction of 1,1,1-trifluoro-2-chloroethane with an excessive amount of potassium acetate in the solvent sulfolane at 210 °C to produce ethyl 2,2,2-trifluoroacetate.

[0005] Another example is US4434297, where CF3CH2Cl reacts with the alkali metal salt potassium acetate of carboxylic acid in N-methyl-2-pyrrolidone to form ethyl 2,2,2-trifluoroacetate, and then hydrolysis to obtain trifluoroethanol.

[0006] Another example is CN1286788C, where γ-butyrolactone reacts with an aqueous potassium hydroxide solution to obtain a solution of potassium γ-hydroxybutyrate, and then 1,1,1-trifluoro-2-chloroethane (R133a) is added, and the reaction is carried out at 200 °C and 1.5 MPa to synthesize trifluoroethanol. This method has high selectivity for trifluoroethanol, can easily separate by-products, and the solvent can be recycled and reused, and has been industrialized. However, due to the batch reaction method, the reaction efficiency is low. In the first 2 h, the reaction conversion is 75%, and in the subsequent 4 - 6 h, only 15% of the reaction occurs, and the reaction ends in 6 - 8 h. The single-pot production capacity is only 80 - 100 kg / m 3 , with low production capacity, making it difficult to industrialize on a large scale; during the production process, the reaction kettle needs to be continuously heated and cooled, resulting in large energy losses, cumbersome industrial operations, low economy, and unstable product quality.

[0007] The continuous production of trifluoroethanol can improve the reaction efficiency, making the production energy-saving and efficient, reducing industrial operations, saving energy and manpower, and the quality of the obtained product is more stable. However, the continuous synthesis of trifluoroethanol from γ-butyrolactone is relatively difficult, and there are mainly the following difficulties: (1) When the content of potassium γ-hydroxybutyrate in the system is ≥15 wt% and the water content is ≤10%, potassium γ-hydroxybutyrate presents as a viscous liquid or even solid and precipitates at the bottom of the system, forming two phases by stratification. When directly feeding continuously in this way, the composition of the fed materials is unstable, resulting in unstable reactions and unable to ensure the product quality; (2) Increasing the water content can make potassium γ-hydroxybutyrate dissolve better in γ-butyrolactone to form a homogeneous system. However, when the water content in the system exceeds 10%, the reaction rate will be severely reduced and the reaction efficiency will be decreased; (3) If γ-butyrolactone and potassium γ-hydroxybutyrate are fed separately, when separating the γ-butyrolactone solution of potassium γ-hydroxybutyrate, water will be separated first, and then γ-butyrolactone will be separated. The obtained potassium hydroxybutyrate contains almost no water and is in a solid state, and cannot circulate. Therefore, how to continuously synthesize trifluoroethanol from γ-butyrolactone is a problem that needs to be solved urgently at present. Summary of the Invention

[0008] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a continuous preparation method of 2,2,2-trifluoroethanol. The present invention realizes the continuous preparation of trifluoroethanol, with simple operation, low energy consumption, effectively improving the reaction efficiency and product production capacity; and the product quality is more stable; the rectification residue liquid can be continuously recycled without treatment, with high economy and being suitable for large-scale industrial production.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is: a continuous preparation method of 2,2,2-trifluoroethanol, comprising the following steps:

[0010] (1) Add KOH, water and γ-butyrolactone into the first reactor and the second reactor respectively, and obtain the first intermediate product and the second intermediate product through hydrolysis reactions respectively, and input the first intermediate product and the second intermediate product into the first feed container and the second feed container respectively;

[0011] (2) Preheat the first intermediate product and continuously feed it into a high-pressure reactor simultaneously with 1,1,1-trifluoro-2-chloroethane and the second intermediate product for a nucleophilic reaction to obtain a reaction solution;

[0012] (3) Perform solid-liquid separation on the reaction solution obtained in step (2), and respectively obtain unreacted 1,1,1-trifluoro-2-chloroethane, bottom liquid and 2,2,2-trifluoroethanol product after rectifying the separated liquid phase.

[0013] As a preferred embodiment of the present invention, the operating conditions of the first reactor in step (1) are as follows: the reaction temperature is 20 to 70 °C, the reaction time is 10 to 60 min, and the mass ratio of KOH, water, and γ-butyrolactone is 1: 0.3 to 0.5: 1.5 to 3.

[0014] As a preferred embodiment of the present invention, the operating conditions of the second reactor in step (1) are as follows: the reaction temperature is 20 to 70 °C, the reaction time is 1 to 30 min, and the mass ratio of KOH, water, and γ-butyrolactone is 1: 0.6 to 1: 35 to 100.

[0015] As a preferred embodiment of the present invention, the preheating temperature in step (2) is 30 to 70 °C, more preferably 40 to 70 °C.

[0016] As a preferred embodiment of the present invention, the operating conditions of the third reactor in step (2) are as follows: the reaction temperature is 150 to 250 °C, the reaction pressure is 1.0 to 4.0 Mpa, and the mass ratio of the first intermediate product, the second intermediate product, and 1,1,1-trifluoro-2-chloroethane is 1: 2 to 15: 0.2 to 2; the reaction temperature is more preferably 180 °C to 210 °C, the reaction pressure is more preferably 1.5 to 2.5 Mpa, and the mass ratio of the first intermediate product, the second intermediate product, and 1,1,1-trifluoro-2-chloroethane is more preferably 1: 5 to 10: 1 to 2.

[0017] As a preferred embodiment of the present invention, the unreacted 1,1,1-trifluoro-2-chloroethane in step (3) is returned to the third reactor for recycling.

[0018] As a preferred embodiment of the present invention, the bottom liquid in step (3) is respectively returned to the first reactor and the second feed container for recycling.

[0019] As a preferred embodiment of the present invention, the mass ratio of the bottom liquid respectively returned to the first reactor and the second feed container is 1: 5 to 10.

[0020] The present invention overcomes the deficiencies existing in the prior art manufacturing process of 2,2,2-trifluoroethanol, and realizes the continuous synthesis of 2,2,2-trifluoroethanol using γ-butyrolactone as the raw material. The present invention mainly adopts the following improvement measures: (1) Study the solubility of potassium γ-hydroxybutyrate in butyrolactone, and investigate the ratio of γ-hydroxybutyrate, water and γ-butyrolactone to obtain a homogeneous potassium γ-hydroxybutyrate butyrolactone solution (the second intermediate); (2) Study the temperature characteristics of the aqueous solution of potassium γ-hydroxybutyrate, so that the obtained aqueous solution of potassium γ-hydroxybutyrate (the first intermediate) can be stably metered into the high-pressure reactor; (3) Control the distillation parameters of the distillation column to make the composition of the bottom liquid of the column basically the same as that of the second intermediate. Therefore, in actual production, after the production is stable, by controlling the flow rate of the reflux of the bottom liquid of the distillation column to the second feed container to be equal to the outflow rate of the second feed container, the feeding of materials to the second reactor can be stopped, and only KOH, water and a small amount of γ-butyrolactone need to be continuously supplemented to the first reactor, further simplifying the process.

[0021] Therefore, the continuous preparation method of 2,2,2-trifluoroethanol of the present invention improves the original batch process to continuous preparation, greatly improves the production efficiency and production capacity, simplifies the operation, saves energy and manpower, the product quality is more stable, realizes the continuous recycling of the distillation residue liquid, and only needs to supplement the necessary raw materials after the production is stable, with high economy and easy to realize large-scale industrial production.

[0022] The reaction principle of the present invention is as follows:

[0023] 1. Synthesis of butyrolactone salt solution

[0024]

[0025] 2. Synthesis of 2,2,2-trifluoroethanol from butyrolactone salt solution

[0026]

[0027] In the present invention, the conversion rate and reaction rate of the nucleophilic reaction in step (2) are affected by the water content in the solution. When the water content is too high, it will affect the nucleophilic addition reaction, the raw material conversion rate and the reaction rate. It is necessary to control the operating conditions of the first reactor and the second reactor, so as to control the water content of the first intermediate product to be 1.7 - 22.0 wt%, preferably 9.0 wt% - 15.0 wt%; the water content of the second intermediate product is 0.5 wt% - 2.0 wt%, preferably 0.5 wt% - 1.0 wt%. At this time, γ-hydroxybutyrate is completely dissolved, and the second intermediate product is a homogeneous system, in which the concentration of potassium γ-hydroxybutyrate solution is 1.40 - 6.84 wt%. Therefore, in the present invention, the preferred operating conditions of the first reactor in step (1) are: the reaction temperature is 20 - 70 °C, the reaction time is 10 - 60 min, and the mass ratio of KOH, water and γ-butyrolactone is 1:0.3 - 0.5:1.5 - 3. The preferred operating conditions of the second reactor are: the reaction temperature is 20 - 70 °C, the reaction time is 1 - 30 min, and the mass ratio of KOH, water and γ-butyrolactone is 1:0.6 - 1:35 - 100.

[0028] In the present invention, the content of all potassium γ-hydroxybutyrate in the first intermediate product and the first intermediate product simultaneously introduced in step (2) in the total solution should be less than 30 wt%, otherwise the salt is likely to precipitate as a solid, making it difficult to stir and react, affecting the reaction rate and raw material conversion rate. Therefore, in the present invention, the mass ratio of the first intermediate product to the second intermediate product is 1:1 - 20, preferably 1:5 - 15.

[0029] In the present invention, the first intermediate product is in a solid state below 0 °C, in a viscous liquid state at 20 - 40 °C, and in a liquid state above 40 °C with a reduced viscosity. Therefore, in step (2) of the present invention, the preferred preheating temperature of the first intermediate product is 30 - 70 °C, more preferably 40 - 70 °C.

[0030] When implementing the present invention, according to the actual production situation, one or several distillation columns can be used for post-treatment. For example, three distillation columns can be operated. Specifically: the reaction liquid obtained in step (2) is separated by a hydrocyclone, and the obtained liquid is first distilled in the first distillation column to obtain 1,1,1-trifluoro-2-chloroethane, which is returned for recycling; then it is distilled in the second distillation column to obtain the finished product of 2,2,2-trifluoroethanol; the heavy components obtained from the second distillation column are distilled to remove water in the third distillation column, and the heavy components of the third distillation column are quantitatively returned to the first reactor and the second feed container respectively. By controlling the distillation parameters such as the number of trays and reflux ratio of the third distillation column, the composition of the distillation residue is made basically the same as that of the second intermediate product.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The process is simple and efficient. The present invention solves the difficulties in the continuous preparation of 2,2,2-trifluoroethanol from γ-butyrolactone in the prior art, realizes the continuous preparation of 2,2,2-trifluoroethanol under relatively low pressure, effectively improves the reaction efficiency, greatly enhances the production capacity of the device, and is easy to realize large-scale industrial production.

[0033] 2. The operation is simple and the energy consumption is low. The present invention realizes the continuous preparation of 2,2,2-trifluoroethanol, significantly simplifies the production process, does not require frequent heating and cooling of the reaction kettle, and effectively saves energy and manpower.

[0034] 3. Green economy and low cost. The rectification residue liquid in the present invention can be continuously recycled, reducing the discharge of three wastes and further reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is the process flow chart of the present invention. SPECIFIC EMBODIMENTS

[0036] The process of the present invention is as Figure 1 shown. KOH, water and γ-butyrolactone are respectively added to the first reactor B1 and the second reactor B2, and hydrolysis reactions are carried out to obtain the first intermediate product C1 and the second intermediate product C2 respectively. The C1 is transported to the first feed container B3, and the C2 is transported to the second feed container B4; the material C1-1 obtained after preheating the first intermediate product C1, 1,1,1-trifluoro-2-chloroethane and the material C2-1 from the second feed container B4 are continuously fed into the high-pressure reactor B5 at the same time for a nucleophilic reaction to obtain the reaction liquid C3; the reaction liquid C3 obtained from the high-pressure reactor B5 is continuously discharged, and solid waste potassium chloride (KCl) and the liquid phase C4 are separated in the hydrocyclone separator B6. The obtained liquid phase C4 is continuously fed into the first rectification column B7 for rectification; the unreacted 1,1,1-trifluoro-2-chloroethane obtained at the top of the first rectification column B7 is returned to the high-pressure reactor B5 for recycling, and the heavy components C5 are obtained at the bottom of the column. The heavy components C5 are continuously fed into the second rectification column B8 for rectification; 2,2,2-trifluoroethanol product is obtained at the top of the second rectification column B8, and heavy components C6 are obtained at the bottom of the column. The heavy components C6 are continuously fed into the third rectification column B9 for rectification; light component water is obtained at the top of the third rectification column B9, and heavy components are obtained at the bottom of the column. A part of the heavy components C7 is returned to the first reactor B1, and the remaining heavy components C7-1 are returned to the second feed container B4.

[0037] The present invention will be described in more detail below through examples, but the present invention is not limited to these examples. Based on the inspiration of the present invention, any obvious transformation or substitution by those skilled in the art for the present invention should also be considered within the protection scope of the present invention.

[0038] Example 1

[0039] (1) KOH: water: γ-butyrolactone was added to the first reactor B1 in a mass ratio of 56:17:105, and a hydrolysis reaction was carried out at 30°C for 40 minutes to obtain a first intermediate product C1. The water content of C1 was 9.55wt% after sampling and analysis; C1 was transported to the first feeding container B3; KOH: water: γ-butyrolactone was added to the second reactor B2 in a mass ratio of 56:43:4300, and a hydrolysis reaction was carried out at 30°C for 20 minutes to obtain a second intermediate product C2. After sampling and analysis, the content of potassium γ-hydroxybutyrate in C2 was 3.23wt%, and the water content was 0.977wt%. Potassium γ-hydroxybutyrate was completely dissolved in C2 to form a homogeneous system; C2 was transported to the second feeding container B4;

[0040] (2) C1 is preheated to 40° C. in the first feed container B3 and then fed simultaneously with C2 and 1,1,1-trifluoro-2-chloroethane at flow rates of 65 kg / h (0.365 kmol / h), 534 kg / h and 98.12 kg / h into the high-pressure reactor B5 for reaction at 180° C. and 1.5 MPa to obtain a reaction liquid C3 with a 2,2,2-trifluoroethanol yield of 75%. The reaction liquid C3 is separated by a hydrocyclone separator B6, and the obtained liquid C4 is first distilled in a first distillation tower B7 to obtain 1,1,1-trifluoro-2-chloroethane, which is then returned to the high-pressure reactor B5 for recycling; and then distilled in a second distillation tower B8 to obtain a finished product of 2,2,2-trifluoroethanol; the heavy component C6 obtained in the second distillation tower B8 is distilled in a second distillation tower B9. Water is distilled out in the three distillation towers B9, and the reflux ratio of the third distillation tower B9 is controlled to be 0.5, the number of plates is 5, the heavy component C6 of the third distillation tower B9 is composed of 3.22wt% potassium γ-hydroxybutyrate and 0.977wt% water content. After the system is stable, the recombinant fraction of the third distillation tower B9 flows back to the first reactor B1 at a flow rate of 38.63kg / h, and flows back to the second feed container B4 at a flow rate of 534kg / h; the flow rate of KOH added to the first reactor B1 is 20.44kg / h, and the amount of H2O is 5.93kg / h; the outflow flow rate of the first feed container B3 is controlled to be 65kg / h, and the outflow flow rate of the second feed container B4 is 534kg / h, and the production capacity of 2,2,2-trifluoroethanol reaches 0.876t / d.

[0041] Example 2

[0042] (1) KOH: water: γ-butyrolactone were added to the first reactor B1 in a mass ratio of 56:20:130, and a hydrolysis reaction was carried out at 50°C for 20 minutes to obtain a first intermediate product C1; sampling and analysis showed that the moisture content of C1 was 9.70wt%; it was transported to the first feeding container B3; at the same time, KOH: water: γ-butyrolactone were added to the second reactor B2 in a mass ratio of 56:50:4800, and a hydrolysis reaction was carried out at 50°C for 10 minutes to obtain a second intermediate product C2. Sampling and analysis showed that the potassium γ-hydroxybutyrate content in C2 was 2.89wt%, the moisture content was 1.02wt%, and the potassium γ-hydroxybutyrate was completely dissolved in C2, presenting a homogeneous system; C2 was transported to the second feeding container B4;

[0043] (2) C1 was preheated to 45° C. in the first feed container B3, and then simultaneously fed into the high-pressure reactor B5 with C2 and 1,1,1-trifluoro-2-chloroethane at flow rates of 98 kg / h (0.424 kmol / h), 520.8 kg / h and 98 kg / h, respectively, to react at 190° C. and 1.8 MPa to obtain reaction liquid C3; the yield of 2,2,2-trifluoroethanol was 80.00%; the reaction liquid C3 was separated by a hydrocyclone separator B6, and the obtained liquid C4 was first distilled in a first distillation tower B7 to obtain 1,1,1-trifluoro-2-chloroethane, which was returned to the high-pressure reactor B5 for recycling; and then distilled in a second distillation tower B8 to obtain a finished product of 2,2,2-trifluoroethanol; the heavy component C6 obtained in the second distillation tower B8 was distilled in a third distillation tower B9 to obtain a 2,2,2-trifluoroethanol product; the heavy component C6 obtained in the second distillation tower B8 was distilled in a third distillation tower B9 to obtain a 2,2,2-trifluoroethanol product; the heavy component C6 obtained in the third distillation tower B9 ... Water is distilled out in the distillation tower B9, and the reflux ratio of the third distillation tower B9 is controlled to be 0.5, the number of plates is 3, the recombined group of the third distillation tower B9 becomes a potassium γ-hydroxybutyrate content of 2.89wt%, and the water content is 1.02wt%. After the system is stable, the recombined branch of the third distillation tower B9 returns to the first reaction container B1 at a flow rate of 64.72kg / h, and returns to the second feed container B4 at a flow rate of 520.8kg / h; the flow rate of KOH added to the first reaction container B1 is 23.77kg / h, and the amount of H2O is 9.50kg / h; the outflow flow of the first feed container B3 is controlled to be 98kg / h, and the outflow flow of the second feed container B4 is 520.8kg / h, and the production capacity of 2,2,2-trifluoroethanol reaches 1.022t / d.

[0044] Example 3

[0045] (1) KOH: water: γ-butyrolactone were added to the first reactor B1 in a mass ratio of 56:15:87, and hydrolysis reaction was carried out at 70°C for 20 minutes to obtain a first intermediate product C1; sampling and analysis showed that the moisture content of C1 was 9.55wt%; it was transported to the first feeding container B3; at the same time, KOH: water: γ-butyrolactone were added to the second reactor B2 in a mass ratio of 56:43:2100, and hydrolysis reaction was carried out at 70°C for 5 minutes to obtain a second intermediate product C2. Sampling and analysis showed that the potassium γ-hydroxybutyrate content in C2 was 6.46wt%, the moisture content was 1.955wt%, and the potassium γ-hydroxybutyrate was completely dissolved in C2 to form a homogeneous system; C2 was transported to the second feeding container B4;

[0046] (2) C1 is preheated to 50°C in the first feed container B3, and then simultaneously fed into the high-pressure reactor B5 with C2 and 1,1,1-trifluoro-2-chloroethane at flow rates of 65 kg / h (0.414 kmol / h), 400 kg / h and 105.9 kg / h, respectively, to react at 205°C and 2.0 MPa to obtain reaction liquid C3; the yield of 2,2,2-trifluoroethanol is 69.70%; the reaction liquid C3 is separated by a hydrocyclone separator B6, and the obtained liquid C4 is first distilled in a first distillation tower B7 to obtain 1,1,1-trifluoro-2-chloroethane, which is then returned to the high-pressure reactor B5 for recycling; and then distilled in a second distillation tower B8 to obtain a finished product of 2,2,2-trifluoroethanol; the recombinant obtained in the second distillation tower B8 Fraction C6 is distilled out of water in the third distillation tower B9, and the reflux ratio of the third distillation tower B9 is controlled to be 0.5, the number of plates is 1, and the recombined group of the third distillation tower B9 becomes a potassium γ-hydroxybutyrate content of 6.46wt%, and the water content is 1.995wt%. After the system is stable, the recombined fraction of the third distillation tower B9 flows back to the first reactor at a flow rate of 35.6kg / h, and flows back to the second feed container B4 at a flow rate of 400kg / h; the flow rate of KOH added to the first reaction container B1 is 23.18kg / h, and the amount of H2O is 6.21kg / h; the outflow flow of the first feed container B3 is controlled to be 65kg / h, and the outflow flow of the second feed container B4 is 400kg / h, and the production capacity of 2,2,2-trifluoroethanol reaches 0.99t / d.

[0047] Example 4

[0048] (1) KOH: water: γ-butyrolactone were added to the first reaction vessel B1 in a mass ratio of 56:25:160, and a hydrolysis reaction was carried out at 30°C for 30 minutes to obtain a first intermediate product C1; sampling and analysis showed that the moisture content of C1 was 14.97wt%; it was transported to the first feeding container B3; at the same time, KOH: water: γ-butyrolactone were added to the second reaction vessel B2 in a mass ratio of 56:43:2100, and a hydrolysis reaction was carried out at 30°C for 30 minutes to obtain a second intermediate product C2. Sampling and analysis showed that the potassium γ-hydroxybutyrate content in C2 was 6.46wt%, and the moisture content was 1.955wt%. The potassium γ-hydroxybutyrate was completely dissolved in C2, presenting a homogeneous system; C2 was transported to the second feeding container B4;

[0049] (2) C1 is preheated to 48°C in the first feed container B3, and then simultaneously fed into the high-pressure reactor B5 with C2 and 1,1,1-trifluoro-2-chloroethane at flow rates of 85 kg / h (0.352 kmol / h), 518 kg / h and 83.4 kg / h, respectively, to react at 210°C and 2.5 MPa to obtain reaction liquid C3; the yield of 2,2,2-trifluoroethanol is 60.0%; the reaction liquid is separated by a hydrocyclone separator B6, and the obtained liquid C4 is first distilled in a first distillation tower B7 to obtain 1,1,1-trifluoro-2-chloroethane, which is returned to the first high-pressure reactor B5 for recycling; and then distilled in a second distillation tower B8 to obtain a finished product of 2,2,2-trifluoroethanol; the product obtained in the second distillation tower B8 The heavy component C6 is distilled to remove water in the third distillation tower B9, and the reflux ratio of the third distillation tower B9 is controlled to be 0.5, the number of plates is 1, and the recombined components of the third distillation tower B9 have a γ-hydroxybutyrate potassium content of 6.46wt% and a water content of 1.995wt%. After the system is stable, the recombined components of the third distillation tower B9 flow back to the first reaction container B1 at a flow rate of 54.00kg / h, and flow back to the second feed container B4 at a flow rate of 518kg / h; the flow rate of KOH added to the first reaction container B1 is 19.71kg / h, and the amount of H2O is 11.92kg / h; the first outflow flow rate is controlled to be 85kg / h, and the second outflow flow rate is 518kg / h, and the production capacity of 2,2,2-trifluoroethanol reaches 0.845t / d.

[0050] Comparative Example 1

[0051] (1) A 0.5 m3 / 3 t / 4 L ... 3 650 kg (7.55 kmol) of γ-butyrolactone was fed into the reactor; 102 kg (0.873 kmol) of 48% potassium hydroxide aqueous solution was added to the dropping funnel and added dropwise over 40 minutes under stirring. During the addition, heat was gradually generated and the internal temperature rose to 50°C; then, water was evaporated at 200°C for 12 hours.

[0052] The concentration of potassium γ-hydroxybutyrate in the γ-butyrolactone solution was tested to be 17.2 wt%. A part of it was taken, neutralized with hydrochloric acid, and the result of HPLC analysis showed that 3.8 wt% of succinic acid peroxide was formed.

[0053] The result of analyzing the water content rate in the obtained γ-butyrolactone solution by the Karl Fischer method showed that the water content rate in the reaction solution was 3.3 wt%.

[0054] (2) 700 kg of the potassium γ-hydroxybutyrate solution was transferred to a 1 m 3 autoclave made of SUS 316 equipped with an electromagnetic stirrer. After sealing it, it was purged with nitrogen three times. Then, 150 kg (1.27 kmol) of R133a from a pressure vessel was added. It was heated to 200 °C within 1 h and reacted at 200 °C and 1.5 MPa for 3 h under stirring. After the reaction, it was cooled to room temperature within 2 h. The gas phase of the reaction solution was tested, and the yield based on potassium γ-hydroxybutyrate was 78%. At this time, the γ-butyrolactone solvent was light brown but showed normal viscosity. The production of 2,2,2-trifluoroethanol was 0.68 kmol, and based on this estimate, the production capacity was 0.27 t / d.

Claims

1. A continuous preparation method of 2, 2, 2-trifluoroethanol, characterized in that, It includes the following steps: (1) Add KOH, water, and γ-butyrolactone into the first reactor and the second reactor respectively. The mass ratio of KOH, water, and γ-butyrolactone in the first reactor is 1: 0.3 - 0.5: 1.5 - 3, and the mass ratio of KOH, water, and γ-butyrolactone in the second reactor is 1: 0.6 - 1: 35 - 100. After hydrolysis reactions, obtain the first intermediate product and the second intermediate product respectively, and input the first intermediate product and the second intermediate product into the first feed container and the second feed container respectively; (2) After preheating the first intermediate product, continuously feed it into the high-pressure reactor simultaneously with 1,1,1-trifluoro-2-chloroethane and the second intermediate product for a nucleophilic reaction to obtain a reaction solution. The mass ratio of the first intermediate product, the second intermediate product, and 1,1,1-trifluoro-2-chloroethane is 1: 2 - 15: 0.2 - 2; (3) Perform solid-liquid separation on the reaction solution obtained in step (2), and after rectification of the separated liquid phase, obtain unreacted 1,1,1-trifluoro-2-chloroethane, bottom liquid, and 2,2,2-trifluoroethanol product respectively.

2. The continuous preparation method of 2, 2, 2-trifluoroethanol according to claim 1, characterized in that, The operating conditions of the first reactor in step (1) are: reaction temperature is 20 - 70 °C, and reaction time is 10 - 60 min.

3. The continuous preparation method of 2, 2, 2-trifluoroethanol according to claim 1, characterized in that, The operating conditions of the second reactor in step (1) are: reaction temperature is 20 - 70 °C, and reaction time is 1 - 30 min.

4. The continuous preparation method of 2, 2, 2-trifluoroethanol according to claim 1, characterized in that, The temperature of the preheating in step (2) is 30 - 70 °C.

5. The continuous preparation method of 2, 2, 2-trifluoroethanol according to claim 1, characterized in that, The operating conditions of the high-pressure reactor in step (2) are: reaction temperature is 150 - 250 °C, and reaction pressure is 1.0 - 4.0 Mpa.

6. The continuous preparation method of 2, 2, 2-trifluoroethanol according to claim 5, characterized in that, The reaction temperature is 180 °C - 210 °C, the reaction pressure is 1.5 - 2.5 Mpa, and the mass ratio of the first intermediate product, the second intermediate product, and 1,1,1-trifluoro-2-chloroethane is 1: 5 - 10: 1 - 2.

7. The continuous preparation method of 2, 2, 2-trifluoroethanol according to claim 1, characterized in that Return the unreacted 1,1,1-trifluoro-2-chloroethane in step (3) to the third reactor for recycling.

8. The continuous preparation method of 2, 2, 2-trifluoroethanol according to claim 1, characterized in that, Return the bottom liquid in step (3) to the first reactor and the second feed container respectively for recycling.

9. The continuous preparation method of 2, 2, 2-trifluoroethanol according to claim 8, characterized in that, The mass ratio of the bottom liquid respectively returned to the first reactor and the second feed container is 1: 5 - 10.

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