Preparation method of 3, 3, 3-trifluoro-2-(trifluoromethyl) propane-1, 2-diol

Abstract

The invention relates to a preparation method of 3, 3, 3-trifluoro-2-(trifluoromethyl) propane-1, 2-diol, which comprises the following steps: adding an aprotic polar solvent, a phase transfer catalyst and hexafluoroisobutene into a sodium hypochlorite aqueous solution, reacting to generate a crude product of the 3, 3, 3-trifluoro-2-(trifluoromethyl) propane-1, 2-diol, and then purifying the crude product to obtain the 3, 3, 3-trifluoro-2-(trifluoromethyl) propane-1, 2-diol. The invention relates to 1, 2, 3-trifluoro-2-(trifluoromethyl) propane-1, 2-diol and a preparation method thereof. According to the preparation method of the 3, 3, 3-trifluoro-2-(trifluoromethyl) propane-1, 2-diol, provided by the invention, the preparation process equipment and operation are simple, the conditions are mild, the reaction time is short, the product is easy to purify, the yield of the 3, 3, 3-trifluoro-2-(trifluoromethyl) propane-1, 2-diol can reach about 60%, and industrial production is easy.

Description

Technical Field

[0001] The invention relates to the technical field of organic fluorine chemical synthesis, and in particular to a method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol. Background Art

[0002] 3,3,3-Trifluoro-2-(trifluoromethyl)propane-1,2-diol is an important fluorinated building block that can be used to synthesize fluorinated polymer monomers required for fine processing in the manufacturing process of semiconductor components. The synthetic monomers required to develop a new generation of photoresist polymers for 157nm microlithography need to have high transparency in the vacuum UV spectral region in addition to being alkali soluble. Studies have shown that introducing C(CF3)2OH fragments into the main chain of the polymer can meet the above goals. The -C(CF3)2OH group has a low absorbance at 157nm, and its acidity makes the synthesized polymer soluble in traditional water-based developers.

[0003] The main preparation technologies for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol are as follows: (1) 3,3,3-trifluoro-2-trifluoromethyl-2-hydroxypropionic acid methyl ester is reduced by sodium borohydride to prepare 3,3,3-trifluoro-2-trifluoromethyl-2-hydroxypropionic acid methyl ester (US20070179309 A1). The 3,3,3-trifluoro-2-trifluoromethyl-2-hydroxypropionic acid methyl ester used in this process is synthesized from heptafluoroisobutylene methyl ether (CAS NO. 360-53-2), which is prepared from highly toxic octafluoroisobutylene as a raw material. Octafluoroisobutylene is one of the highly toxic substances in the organic fluorine industry and one of the important substances verified by the United Nations Organization for the Prohibition of Chemical Weapons (OPCW). Its molecular structure is (CF3)2C=CF2, boiling point is 6.5-7.0℃, colorless gas with a slight grass smell. The maximum allowable concentration of harmful substances in the air is 0.1mg / m 3(2) Using hexafluoroisobutylene as the starting material, 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol was prepared in two steps: first, hexafluoroisobutylene was oxidized to synthesize 2,2-bis(trifluoromethyl)oxirane with a yield of 75% (The Journal of Chemical Thermodynamics, Volume 125, 2004, pp. 531-536); then, 2,2-bis(trifluoromethyl)oxirane was hydrolyzed to 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol with a yield of 55% (Synthesis, No. 15, 2225-2231). The total yield of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol synthesized by the two-step method was only 45%. Among them, the existing hydrolysis process of 2,2-bis(trifluoromethyl)ethylene oxide uses tetrahydrofuran (THF) as a solvent. Under a high temperature condition of 175°C, 2,2-bis(trifluoromethyl)ethylene oxide and water react for 12 hours to generate 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol. The hydrolysis reaction needs to be carried out under high temperature and high pressure conditions; and the oxidant used for oxidizing hexafluoroisobutylene needs to be separated from 2,2-bis(trifluoromethyl)ethylene oxide before the hydrolysis reaction can be carried out, so that the two-step synthesis of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol has the problems of a long synthesis process and a low yield. Summary of the invention

[0004] In view of the problem that the synthesis process of preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol by a two-step reaction is long and the yield is low, the present invention provides a preparation method of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, which can complete the preparation of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol by one feeding, has mild reaction conditions, simplifies the process flow, improves the yield, and is conducive to realizing industrial production.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0006] The present invention provides a method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, comprising the following steps:

[0007] A non-protonic polar solvent, a phase transfer catalyst and hexafluoroisobutylene are added to a sodium hypochlorite aqueous solution to react to generate a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, and then the crude product is purified to obtain 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol.

[0008] Preferably, a non-protonic polar solvent, a phase transfer catalyst and hexafluoroisobutylene are added to an aqueous sodium hypochlorite solution to react to generate a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, which specifically comprises the following steps:

[0009] A non-protonic polar solvent, a phase transfer catalyst and hexafluoroisobutylene are added to a sodium hypochlorite aqueous solution for reaction. The hexafluoroisobutylene generates 2,2-bis(trifluoromethyl)ethylene oxide under oxidation reaction conditions, and then 2,2-bis(trifluoromethyl)ethylene oxide is hydrolyzed under hydrolysis reaction conditions provided by the sodium hypochlorite aqueous solution to generate a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol.

[0010] Preferably, the oxidation reaction conditions include oxidation reaction temperature and oxidation reaction time, the oxidation reaction temperature is -20°C to 15°C; the oxidation reaction time is 0.5h to 5h.

[0011] Preferably, the oxidation reaction temperature is -2°C to 3°C; the oxidation reaction time is 1.5h to 3h.

[0012] Preferably, the hydrolysis includes a hydrolysis reaction temperature and a hydrolysis reaction time, wherein the hydrolysis reaction temperature is -20°C to 70°C, and the hydrolysis reaction time is 3h to 15h.

[0013] Preferably, the hydrolysis reaction temperature is 20°C to 30°C, and the hydrolysis reaction time is 5h to 8h.

[0014] Preferably, the molar ratio of the hexafluoroisobutylene to the sodium hypochlorite aqueous solution is in the range of (0.5-1.5):1.

[0015] Preferably, the pH of the sodium hypochlorite aqueous solution is 8 to 13, and the mass concentration of effective chloride ions in the sodium hypochlorite aqueous solution is 3% to 15%.

[0016] Preferably, the molar ratio of the hexafluoroisobutylene to the aprotic polar solvent is in the range of (0.3-0.8):1.

[0017] Preferably, the molar ratio of the hexafluoroisobutylene to the phase transfer catalyst is in the range of (10-100):1.

[0018] Preferably, the aprotic polar solvent includes one or more of methanol, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, and acetonitrile.

[0019] Preferably, the phase transfer catalyst includes one or more of methyltrioctylammonium chloride, tetrabutylammonium bromide, and tetrabutylammonium chloride.

[0020] Compared with the prior art, the preparation method of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol provided by the present invention uses sodium hypochlorite as an oxidant for oxidizing hexafluoroisobutylene and also provides a reaction environment for ring-opening of 2,2-bis(trifluoromethyl)ethylene oxide, so that the two-step reaction of oxidation of hexafluoroisobutylene and hydrolysis of 2,2-bis(trifluoromethyl)ethylene oxide can be completed by one-time feeding, the reaction conditions are mild, the yield is increased from 45% to about 60%, the cost of the existing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol synthesis process is effectively reduced, the process flow is simplified, and it is more conducive to industrial production. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] The present invention provides a method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, comprising the following steps:

[0023] A non-protonic polar solvent, a phase transfer catalyst and hexafluoroisobutylene are added to a sodium hypochlorite aqueous solution to react and generate a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, and then the crude product is purified to obtain 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol.

[0024] Specifically, the preparation method of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol specifically comprises the following steps: (1) adding a sodium hypochlorite aqueous solution into a three-necked flask, adding a non-protonic polar solvent, a phase transfer catalyst and hexafluoroisobutylene to react;

[0025] (2) After the reaction is completed, the liquid is separated, and then the organic layer is distilled to obtain a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, and further distilled to obtain a high-purity 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol product that meets the application conditions of electronic devices. The above-mentioned reaction container is a three-necked flask, and it can be understood that the reaction container can also be other containers, such as a high-pressure reactor, etc., which is not limited in this application.

[0026] Compared with the prior art, the preparation method of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol provided by the present application uses sodium hypochlorite as an oxidant for oxidizing hexafluoroisobutylene and also provides a reaction environment for the ring-opening of 2,2-bis(trifluoromethyl)ethylene oxide, so that the two-step reaction of the oxidation of hexafluoroisobutylene and the hydrolysis of 2,2-bis(trifluoromethyl)ethylene oxide can be completed by one feeding, the reaction conditions are mild, the yield is improved, and the cost of the existing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol synthesis process is effectively reduced, the process flow is simplified, and it is more conducive to the realization of industrial production.

[0027] In some embodiments, a non-protonic polar solvent, a phase transfer catalyst and hexafluoroisobutylene are added to an aqueous sodium hypochlorite solution to react to generate a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, specifically comprising the following steps:

[0028] A non-protonic polar solvent, a phase transfer catalyst and hexafluoroisobutylene are added to an aqueous sodium hypochlorite solution, and the hexafluoroisobutylene generates 2,2-bis(trifluoromethyl)ethylene oxide under oxidation reaction conditions, and then 2,2-bis(trifluoromethyl)ethylene oxide is hydrolyzed under hydrolysis reaction conditions provided by the aqueous sodium hypochlorite solution to generate a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol.

[0029] Under oxidation reaction conditions, an aqueous sodium hypochlorite solution can oxidize hexafluoroisobutylene to generate 2,2-bis(trifluoromethyl)ethylene oxide, and at the same time, under the reaction system, 2,2-bis(trifluoromethyl)ethylene oxide is hydrolyzed and ring-opened to generate a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol. Compared with the prior art, the preparation method adopted in the present application can realize one-pot preparation of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol after one-time feeding, thereby reducing production costs, simplifying the process flow, and realizing industrial production.

[0030] In some embodiments, the oxidation reaction conditions include oxidation reaction temperature and oxidation reaction time, the oxidation reaction temperature is -20°C to 15°C; the oxidation reaction time is 0.5h to 5h.

[0031] Specifically, sodium hypochlorite can oxidize hexafluoroisobutylene to generate 2,2-bis(trifluoromethyl)ethylene oxide under oxidation reaction conditions, wherein the oxidation reaction temperature is -20°C to 15°C, the oxidation reaction time is 0.5h to 5h, the oxidation reaction temperature is low, the reaction time is short, and the production cost is greatly reduced. If the oxidation reaction temperature is lower than -20°C, the sodium hypochlorite aqueous solution solidifies and is difficult to disperse, and hexafluoroisobutylene cannot be oxidized, or the oxidation reaction rate is low. If the oxidation reaction temperature is higher than 15°C, the temperature is too high, the reaction by-products increase, the selectivity decreases, and the yield of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol decreases. If the first reaction time is lower than 0.5h, the reaction time is short, part of the hexafluoroisobutylene is not completely reacted, and the yield of the generated 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol is low. If the first reaction time is higher than 5h, the reaction time is long, the process time increases, and the cost increases.

[0032] The oxidation reaction temperature can be -20°C to -15°C, -15°C to -10°C, -10°C to -5°C, -5°C to -3°C, -3°C to 0°C, 2°C to 5°C, etc., as long as the oxidation reaction temperature is within the range of -20°C to 15°C.

[0033] The first reaction time can be 1.5 h, 1.8 h, 2.0 h, 2.2 h, 2.6 h, 2.9 h, 3.0 h, etc., as long as the first reaction time is within the range of 0.5 h to 5.0 h.

[0034] In some preferred embodiments, the oxidation reaction temperature is -5°C to 5°C, and the first reaction time is 1.5h to 3.0h.

[0035] In some preferred embodiments, the oxidation reaction temperature is -2°C to 3°C; the oxidation reaction time is 1.5h to 3.0h.

[0036] In some embodiments, the hydrolysis includes a hydrolysis reaction temperature and a hydrolysis reaction time, wherein the hydrolysis reaction temperature is -20°C to 70°C, and the hydrolysis reaction time is 3h to 15h.

[0037] Specifically, under the hydrolysis reaction conditions provided by sodium hypochlorite, 2,2-bis(trifluoromethyl)ethylene oxide is ring-opened and hydrolyzed to generate a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, the hydrolysis reaction temperature is between -20°C and 70°C, the hydrolysis reaction time is between 3h and 15h, the hydrolysis reaction temperature is low, energy consumption is reduced, and the production cost is reduced. If the hydrolysis reaction temperature is lower than -20°C, the sodium hypochlorite aqueous solution solidifies and is difficult to disperse, 2,2-bis(trifluoromethyl)ethylene oxide cannot be hydrolyzed, or the hydrolysis rate is low. If the hydrolysis reaction temperature is higher than 70°C, the temperature is too high, the reaction by-products increase, the selectivity decreases, and the yield of the generated 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol decreases. If the hydrolysis reaction time is less than 3 hours, the reaction time is short, 2,2-bis(trifluoromethyl)ethylene oxide cannot be completely hydrolyzed, and the yield of the generated 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol is low. If the hydrolysis reaction time is more than 15 hours, the hydrolysis reaction time is long, the process time is increased, and the preparation cost is increased.

[0038] Specifically, the hydrolysis reaction temperature can be -20℃~-10℃, -10℃~0℃, 0℃~10℃, 10℃~20℃, 20℃~30℃, 30℃~40℃, 40℃~50℃, 50℃~60℃, 60℃~70℃, etc., as long as the hydrolysis reaction temperature is between -20℃ and 70℃.

[0039] The hydrolysis reaction time can be 3h, 3.5h, 4h, 4.5h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, etc., as long as the hydrolysis reaction time is between 3h and 15h.

[0040] In some preferred embodiments, the hydrolysis reaction temperature is 20°C to 30°C, and the hydrolysis reaction time is 3h to 15h.

[0041] In some preferred embodiments, the hydrolysis reaction temperature is 20°C to 30°C, and the hydrolysis reaction time is 5h to 8h.

[0042] In some embodiments, the molar ratio of the hexafluoroisobutylene to the sodium hypochlorite aqueous solution is in the range of (0.5-1.5):1.

[0043] The molar ratio of hexafluoroisobutylene to the sodium hypochlorite aqueous solution is within the above range, which helps sodium hypochlorite to oxidize hexafluoroisobutylene to 2,2-bis(trifluoromethyl)oxirane. If the molar ratio of hexafluoroisobutylene to the sodium hypochlorite aqueous solution is lower than 0.5, the amount of acetonitrile dissolved in the aqueous phase: sodium hypochlorite aqueous solution increases, the amount of acetonitrile dissolved in the organic phase: hexafluoroisobutylene decreases, the contact amount of hexafluoroisobutylene and sodium hypochlorite decreases, and the product yield decreases; if the molar ratio of hexafluoroisobutylene to the sodium hypochlorite aqueous solution is higher than 1.5, the amount of hexafluoroisobutylene added is large, the hexafluoroisobutylene reaction is incomplete, the recovery cost of the product increases, and the yield of the product decreases.

[0044] Specifically, the molar ratio of hexafluoroisobutylene to the aqueous sodium hypochlorite solution can be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.3, 1.5, etc., as long as the molar ratio of hexafluoroisobutylene to the aqueous sodium hypochlorite solution is within the range of 0.5 to 1.5.

[0045] In some embodiments, the molar ratio of hexafluoroisobutylene to the sodium hypochlorite aqueous solution is 0.8-1; the added hexafluoroisobutylene can be substantially oxidized to 2,2-bis(trifluoromethyl)ethylene oxide, thereby increasing the yield of the product.

[0046] In some embodiments, the pH of the sodium hypochlorite aqueous solution is 8-13, and the mass concentration of effective chloride ions in the sodium hypochlorite aqueous solution is 3%-15%.

[0047] Controlling the pH of the sodium hypochlorite aqueous solution can effectively control the hydrolysis reaction of 2,2-bis(trifluoromethyl)ethylene oxide, and is helpful to achieve a two-step reaction of oxidation of hexafluoroisobutylene and hydrolysis of 2,2-bis(trifluoromethyl)ethylene oxide by one feeding.

[0048] Controlling the mass concentration of effective chlorine ions in the sodium hypochlorite aqueous solution to 3% to 15% is conducive to the oxidation of hexafluoroisobutylene and controls the normal progress of the oxidation reaction. If the mass concentration of effective chlorine ions in the sodium hypochlorite aqueous solution is too low, the reaction speed slows down, and the amount of sodium hypochlorite aqueous solution added needs to be increased, the catalyst is diluted, and the progress of the hexafluoroisobutylene oxidation reaction is affected; if the mass concentration of effective chlorine ions is too high, there is no obvious effect on the reaction, but the mass concentration of effective chlorine ions in industrial-grade sodium hypochlorite aqueous solution is usually less than 15%, and the mass concentration of effective chlorine ions decreases during long-term storage.

[0049] In some embodiments, the molar ratio of the hexafluoroisobutylene to the aprotic polar solvent is in the range of (0.3-0.8):1.

[0050] The aprotic polar solvent is mainly used to dissolve hexafluoroisobutylene, which is convenient for the oxidation reaction of hexafluoroisobutylene. If the molar ratio of hexafluoroisobutylene to the aprotic polar solvent is too low, the content of the aprotic polar solvent is too much, and the excessive aprotic polar solvent will dilute the reactants and cause the oxidation reaction to be poor. If the molar ratio of hexafluoroisobutylene to the aprotic polar solvent is too high, the content of the aprotic polar solvent is too little, and the too little aprotic polar solvent will cause the hexafluoroisobutylene to be unable to be completely dissolved, and the yield is reduced.

[0051] Specifically, the molar ratio of hexafluoroisobutylene to the aprotic polar solvent can be 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, etc., as long as the molar ratio of hexafluoroisobutylene to the aprotic polar solvent is in the range of 0.3 to 0.8.

[0052] In some preferred embodiments, the molar ratio of the hexafluoroisobutylene to the aprotic polar solvent is in the range of (0.5-0.6): 1. The molar ratio of the two within this range is conducive to the aprotic polar solvent to better dissolve hexafluoroisobutylene, increase the reaction rate, and increase the yield of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol.

[0053] In some embodiments, the molar ratio of the hexafluoroisobutylene to the phase transfer catalyst is in the range of (10-100):1.

[0054] Hexafluoroisobutylene and sodium hypochlorite aqueous solution are immiscible, and the added phase transfer catalyst has the function of transferring hypochlorite ions in the sodium hypochlorite aqueous solution. The phase transfer catalyst can transfer the hypochlorite ions in the sodium hypochlorite aqueous solution to the aprotic polar solvent, thereby achieving the effect of hypochlorite ions oxidizing hexafluoroisobutylene. If the molar ratio of hexafluoroisobutylene to the phase transfer catalyst is higher than 100, that is, the phase transfer catalyst contained is too little, which will result in a slow reaction rate, or the oxidation reaction of hexafluoroisobutylene cannot occur.

[0055] Specifically, the molar ratio of hexafluoroisobutylene to the phase transfer catalyst can be 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, etc., as long as the molar ratio of hexafluoroisobutylene to the phase transfer catalyst is in the range of 10 to 100:1.

[0056] In some preferred embodiments, the molar ratio of the hexafluoroisobutylene to the phase transfer catalyst is in the range of (20-50): 1. The molar ratio of the two is within this range, which is conducive to the phase transfer catalyst transferring the hypochlorite ions in the sodium hypochlorite aqueous solution to the aprotic polar solvent, thereby achieving the effect of hypochlorite ions oxidizing hexafluoroisobutylene.

[0057] In some embodiments, the aprotic polar solvent includes one or more of methanol, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, and acetonitrile.

[0058] In some preferred embodiments, the aprotic polar solvent is acetonitrile.

[0059] In some embodiments, the phase transfer catalyst includes one or more of methyltrioctylammonium chloride, tetrabutylammonium bromide, and tetrabutylammonium chloride.

[0060] In some preferred embodiments, the phase transfer catalyst is methyltrioctylammonium chloride.

[0061] The present invention is further described below by way of examples.

[0062] Example 1

[0063] This example is used to illustrate a method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol disclosed in the present invention.

[0064] In a 2L three-necked flask, 1000g of sodium hypochlorite aqueous solution (effective chloride ion mass concentration of 4.5%, 0.635mol), 8g of methyltrioctyl ammonium chloride phase transfer catalyst and 47g of aprotic polar solvent acetonitrile were added, wherein the pH value of the sodium hypochlorite aqueous solution was 12.5. The temperature of the dry ice temperature-controlled flask was between -3 and 2°C, and 100g (0.61mol) of hexafluoroisobutylene was slowly introduced, and the oxidation reaction was carried out within the oxidation reaction temperature range of -3 to 2°C, and the oxidation reaction time was controlled to 3h, and the hexafluoroisobutylene was oxidized to 2,2-bis(trifluoromethyl)ethylene oxide. After the oxidation reaction is completed, a hydrolysis reaction is carried out, the temperature is slowly raised to a range of 20 to 30°C, and the reaction is kept warm for 12 hours; that is, the hydrolysis reaction temperature is 20 to 30°C, the hydrolysis reaction time is 12 hours, and the sodium hypochlorite aqueous solution provides the reaction conditions for the hydrolysis, and 2,2-bis(trifluoromethyl)ethylene oxide is hydrolyzed into 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol. After the hydrolysis reaction is completed, a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol is obtained.

[0065] The crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol was separated and purified by distillation to obtain a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, which was then purified by rectification to obtain a white crystal product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol. The white crystal product was weighed and chromatographically detected to obtain a selectivity of 91.1% and a yield of 64%.

[0066] Example 2

[0067] In a 5L three-necked flask, 3200g of sodium hypochlorite aqueous solution (effective chloride ion concentration of 12%, 5.42mol), 32.8g of phase transfer catalyst methyl trioctyl ammonium chloride, and 403g of aprotic polar solvent acetonitrile were added. The pH value of the sodium hypochlorite aqueous solution was 12.5. Dry ice was used to control the temperature to -3 to 2°C, and 602.8g (3.674mol) of hexafluoroisobutylene was slowly introduced. The oxidation reaction was carried out within the oxidation reaction temperature range of -3 to 2°C, and the oxidation reaction time was controlled to 3h to oxidize hexafluoroisobutylene to 2,2-bis(trifluoromethyl)ethylene oxide. After the oxidation reaction is completed, a hydrolysis reaction is carried out, the temperature is slowly raised to 20-30°C, and the reaction is kept warm for 12 hours; that is, the hydrolysis reaction temperature is 20-30°C, the hydrolysis reaction time is 12 hours, and the sodium hypochlorite aqueous solution provides the reaction conditions for the hydrolysis. The sodium hypochlorite aqueous solution is a hydrolysis catalyst, and 2,2-bis(trifluoromethyl)ethylene oxide is hydrolyzed into 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol. After the hydrolysis reaction is completed, a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol is obtained.

[0068] The crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol was separated and purified by distillation to obtain a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, which was then purified by rectification to obtain white crystals of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol. The finished white crystals were weighed and chromatographically detected to obtain a selectivity of 90% and a yield of 62%.

[0069] Example 3

[0070] The difference between Example 3 and Example 2 is that the type of aprotic polar solvent added is different, and the rest is the same as Example 2. Specifically, in Example 3, 403 g of aprotic polar solvent tetrahydrofuran is added.

[0071] The white crystals of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol obtained in Example 3 were weighed, and the chromatographic detection showed that the selectivity was 91% and the yield was 45%.

[0072] Embodiment 4-16

[0073] The differences between Examples 4-16 and Example 2 are: the mass of the phase transfer catalyst is different, the mass of the aprotic polar solvent is different, the mass of hexafluoroisobutylene is different; the oxidation reaction temperature, oxidation reaction time, hydrolysis reaction temperature, and hydrolysis reaction time are different, as shown in Table 1; the rest is the same as Example 2.

[0074] Table 1

[0075]

[0076] Comparative Example 1

[0077] 3145g of sodium hypochlorite aqueous solution (effective chloride ion concentration of 9%, 4 mol), 48.4g of methyltrioctylammonium chloride, and 298g of acetonitrile were placed in a 5L three-necked flask, wherein the pH value of the sodium hypochlorite aqueous solution was 12.5. Dry ice was used to control the temperature to -3 to 2°C, and 600g (3.657 mol) of hexafluoroisobutylene was slowly introduced, and the oxidation reaction was carried out within the oxidation reaction temperature range of -3 to 2°C, and the oxidation reaction time was controlled to 1.5h, and the hexafluoroisobutylene was oxidized to 2,2-bis(trifluoromethyl)ethylene oxide. After the reaction is completed, liquid separation is performed to obtain a crude product containing hexafluoroisobutylene, 2,2-bis(trifluoromethyl)ethylene oxide and acetonitrile. After distilling and separating the unreacted hexafluoroisobutylene, dichloromethane and sulfuric acid aqueous solution are added, the temperature is raised to 170-180°C, and the reaction is kept warm for 12 hours to hydrolyze 2,2-bis(trifluoromethyl)ethylene oxide into a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol. White crystals of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol are obtained by distillation and purification. After weighing and chromatographic detection, it is found that the selectivity is 90% and the yield is 43%.

[0078] Comparative Example 2

[0079] 1kg of water was added to a 2L three-necked flask, and 69g (1.93mol) of sodium borohydride was dissolved. The temperature was controlled within 50°C in a dry ice water bath, and 515g (2.28mol) of 2-hydroxy-3,3,3-trifluoro-2-trifluoromethyl propionic acid methyl ester was added dropwise. After the addition was completed, the mixture was stirred and dispersed at room temperature for 1h, and then 300mL of 36% aqueous hydrochloric acid solution was added dropwise. After the addition was completed, the mixture was filtered to remove the salt generated during the reaction, the filtrate was collected, and 500mL of 2-(isopropylamino)ethanol was added to the filtrate to extract twice to obtain an organic layer, which was then dried and evaporated to dryness. The organic layer was purified by rectification to obtain white crystals of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, which were weighed and chromatographically detected to obtain a selectivity of 98.1% and a yield of 36%.

[0080] The crude 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol prepared in Example 1-16 was subjected to liquid separation and distillation purification to obtain white crystals of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol. The finished white crystals were weighed and the selectivity and yield were obtained after chromatographic detection. The specific data are shown in Table 2.

[0081] The selectivity and yield data of Comparative Examples 1-2 are shown in Table 2.

[0082] Here, the selectivity is the target product generated / all products generated×100%.

[0083] Yield = actual yield of target product / theoretical yield of target product × 100%.

[0084] The target product is 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol.

[0085] Table 2

[0086]

[0087]

[0088] It can be seen from Tables 1 and 2 above that, in comparison between Examples 1-2, Examples 3-8 and Comparative Example 2, in Comparative Example 2, 2-hydroxy-3,3,3-trifluoro-2-trifluoromethylpropionic acid methyl ester is hydrolyzed to generate 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol; Comparative Example 2 directly hydrolyzes the ester to obtain alcohol, and the yield is relatively low, indicating that directly using an aqueous sodium hypochlorite solution as an oxidant and performing a hydrolysis reaction under this system to prepare 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol can improve the yield of the product. Comparative Example 1 uses sodium hypochlorite, methyl trioctyl ammonium chloride and acetonitrile to prepare 2,2-bis(trifluoromethyl)ethylene oxide, and then adds dichloromethane and sulfuric acid aqueous solution to hydrolyze 2,2-bis(trifluoromethyl)ethylene oxide to 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol. Compared with Comparative Example 2, the selectivity and yield of the product are reduced. Compared with Comparative Example 1 and Examples 1-8, the yield of the product is too low; it shows that directly using sodium hypochlorite aqueous solution as oxygen The invention discloses a method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol by a one-pot method. The method also provides a method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol by a one-pot method. The method also provides a method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol by a mild reaction condition, thereby effectively reducing the cost of the existing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol synthesis process, improving the yield, simplifying the process flow, and being more conducive to realizing industrial production.

[0089] Compared with Examples 8-10, Example 2 has a higher yield of the product prepared when the oxidation reaction temperature is between -3 and 2°C.

[0090] Compared with Example 11, the hydrolysis reaction temperature is too high, and the selectivity and yield are reduced, indicating that the temperature is increased, the by-products generated increase, the reaction selectivity decreases, and the yield of the generated 3,3,3-trifluoro-2-(trifluoromethyl) propane-1,2-diol is low. Compared with Example 12, the molar ratio of hexafluoroisobutylene to aprotic polar solvent is greater than 0.8, and the yield is reduced, indicating that the feed ratio of aprotic polar solvent is too small, and too little aprotic polar solvent will cause hexafluoroisobutylene to not be completely dissolved, and the yield is reduced. Compared with Example 16, the molar ratio of hexafluoroisobutylene to aprotic polar solvent is less than 0.3, and the amount of aprotic polar solvent is too much. Too much aprotic polar solvent will dilute the reactants, resulting in poor oxidation reaction effect, resulting in low product yield; it shows that the molar ratio of hexafluoroisobutylene to aprotic polar solvent is in the range of 0.3 to 0.8, and the product has a higher yield. Comparing Examples 1, 2 and 4, when the molar ratio of hexafluoroisobutylene to the aprotic polar solvent is in the range of 0.5 to 0.6, the product has a higher yield.

[0091] In comparison between Example 2 and Example 13, the molar ratio of hexafluoroisobutene to the phase transfer catalyst is greater than 100, and the yield of the product is reduced. Too little phase transfer catalyst will result in a slow reaction rate, or the oxidation reaction of hexafluoroisobutene cannot occur, resulting in a reduced yield of the product; indicating that the molar ratio of hexafluoroisobutene to the phase transfer catalyst is in the range of (10 to 100): 1, and the yield of the product is high. In comparison between Example 2 and Example 6, when the molar ratio of the two is in the range of (20 to 50): 1, the product has a higher yield.

[0092] In Example 2, when the molar ratio of hexafluoroisobutylene to the sodium hypochlorite aqueous solution is lower than 0.5, the amount of acetonitrile dissolved in the sodium hypochlorite aqueous solution increases, while the amount of acetonitrile dissolved in the hexafluoroisobutylene in the organic phase decreases, the contact amount between hexafluoroisobutylene and sodium hypochlorite decreases, and the yield of the product decreases; when the molar ratio of hexafluoroisobutylene to the sodium hypochlorite aqueous solution is higher than 1.5, the amount of hexafluoroisobutylene added is large, the hexafluoroisobutylene reaction is incomplete, and the yield of the product decreases; this indicates that the molar ratio of hexafluoroisobutylene to the sodium hypochlorite aqueous solution is in the range of (0.5-1.5):1, and the yield of the product is higher. In Example 1 and 2, when the molar ratio of hexafluoroisobutylene to the sodium hypochlorite aqueous solution is in the range of (0.8-1):1, the product has a higher yield.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, characterized in that: The following steps are involved: A non-protonic polar solvent, a phase transfer catalyst and hexafluoroisobutylene are added to a sodium hypochlorite aqueous solution to react and generate a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, and then the crude product is purified to obtain 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol.

2. The method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol according to claim 1, characterized in that: A non-protonic polar solvent, a phase transfer catalyst and hexafluoroisobutylene are added to a sodium hypochlorite aqueous solution to react and generate a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol, which specifically includes the following steps: A non-protonic polar solvent, a phase transfer catalyst and hexafluoroisobutylene are added to a sodium hypochlorite aqueous solution for reaction. The hexafluoroisobutylene generates 2,2-bis(trifluoromethyl)ethylene oxide under oxidation reaction conditions, and then 2,2-bis(trifluoromethyl)ethylene oxide is hydrolyzed under hydrolysis reaction conditions provided by the sodium hypochlorite aqueous solution to generate a crude product of 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol.

3. The method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol according to claim 2, characterized in that: The oxidation reaction conditions include oxidation reaction temperature and oxidation reaction time. The oxidation reaction temperature is -20°C to 15°C; the oxidation reaction time is 0.5h to 5h.

4. The method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol according to claim 3, characterized in that: The hydrolysis includes a hydrolysis reaction temperature and a hydrolysis reaction time. The hydrolysis reaction temperature is -20°C to 70°C, and the hydrolysis reaction time is 3h to 15h.

5. The method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol according to claim 1 or 2, characterized in that: The molar ratio of the hexafluoroisobutylene to the sodium hypochlorite aqueous solution is in the range of (0.5-1.5):

1.

6. The method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol according to claim 1 or 2, characterized in that: The pH of the sodium hypochlorite aqueous solution is 8-13, and the mass concentration of effective chloride ions in the sodium hypochlorite aqueous solution is 3%-15%.

7. The method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol according to claim 1 or 2, characterized in that: The molar ratio of the hexafluoroisobutylene to the aprotic polar solvent is in the range of (0.3-0.8):

1.

8. The method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol according to claim 1 or 2, characterized in that: The molar ratio of the hexafluoroisobutylene to the phase transfer catalyst is in the range of (10-100):

1.

9. The method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol according to claim 1 or 2, characterized in that: The aprotic polar solvent includes one or more of methanol, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, and acetonitrile.

10. The method for preparing 3,3,3-trifluoro-2-(trifluoromethyl)propane-1,2-diol according to claim 1 or 2, characterized in that: The phase transfer catalyst includes one or more of methyltrioctylammonium chloride, tetrabutylammonium bromide and tetrabutylammonium chloride.

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