JP2009051798A - Production method of hexafluoroisopropanol - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for obtaining hexafluoroisopropanol from hexafluoroacetone as a raw material in a sufficiently satisfactory yield from an industrial viewpoint which can be carried out at relatively low pressure at a relatively low temperature and permits simplification of a purification step because the product essentially contains no excessively hydrogenated by-products. <P>SOLUTION: The production method of hexafluoroisopropanol comprises hydrogenating hexafluoroacetone by bringing it into contact with a hydrogen gas at -20 to 60°C in a hydrogen fluoride solvent in the presence of a metal catalyst such as palladium or ruthenium or a catalyst comprising the metal catalyst carried on a carrier. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing hexafluoroisopropanol by hydrogenating hexafluoroacetone, and more specifically, high purity by hydrogenolysis of a hexafluoroacetone / hydrogen fluoride adduct in a hydrogen fluoride solvent in the presence of a catalyst. This invention relates to a method for producing hexafluoroisopropanol.

  Hexafluoroisopropanol is produced in large quantities as a solvent that exhibits a specific solubility in polymers and as an intermediate for inhalation anesthetics. Hexafluoroisopropanol is usually produced by reduction of hexafluoroacetone, and various methods have been proposed depending on the combination of the form of hexafluoroacetone as a raw material, reaction form, reducing agent, type of catalyst, and the like.

In the gas phase method, anhydrous hexafluoroacetone is catalyzed by Cu—Cr ₂ O ₃ —CaF ₂ (Patent Document 1), Pd / Al ₂ O ₃ (Patent Document 2), Pd / C (Patent Document 3), and the like. A method of hydrogenating with hydrogen is known, and a method of hydrogenating hexafluoroacetone hydrate with hydrogen in the presence of a nickel catalyst and / or a palladium catalyst is known (Patent Document 4).

  As a method for producing hexafluoroisopropanol with hydrogen gas in a liquid phase, a method using hexafluoroacetone hydrate and a method using hexafluoroacetone anhydride are known. As an anhydride, a method of reacting platinum oxide as a catalyst at a pressure of 20.0 to 90.0 MPa (200 to 900 atm) at 110 ° C. to 150 ° C. for 6 hours (Patent Document 5), in a hexafluoroisopropanol solvent In which platinum oxide is used as a catalyst at a pressure of 2.72 MPa (27.2 atm) and reaction is carried out at 55 ° C. to 80 ° C. for 2 hours (Patent Document 6), rhodium / C as a catalyst at a pressure of 3.5 to 3.6 MPa 35 to 36 atmospheres) and a method of reacting at 65 ° C. for 1 hour (Patent Document 7) and the like have been reported, but hexafluoroacetone having a low boiling point (−27 ° C.) has a high vapor pressure, and in these methods, a reactor is used. The internal pressure tends to increase.

Moreover, in the method of hydrogenating hexafluoroacetone hydrate in the liquid phase, palladium / C is used as a catalyst and the pressure is 0.35 to 0.7 MPa (3.5 to 7 kg / cm ² ), 70 ° C. to 75 ° C. For 3.5 hours (Patent Document 8), a reaction using palladium / Al ₂ O ₃ as a catalyst at a pressure of 0.5 MPa (5 kg / cm ² ) at 100 ° C. for 6 hours (Patent Document 9), etc. There is. Thus, in order to hydrogenate a hydrate in a liquid phase, a relatively high temperature and a long reaction time are required.
Further, as a method using a reducing agent other than hydrogen, a method using hexafluoroacetone anhydride in a methanol solvent and sodium borohydride as a reducing agent, similarly in an oxygen-containing solvent such as diethyl ether, methanol, isopropanol, tetrahydrofuran, etc. A method using lithium aluminum hydride, calcium hydride, sodium hydride or the like as a reducing agent has been reported (Patent Document 5).
In any of these reduction methods, the reduction proceeds excessively, and 1,1,1-trifluoroacetone and 1,1,1-trifluoroisopropanol, which are perreducts, are produced as by-products. -Trifluoroacetone is an impurity that is difficult to separate when contained in the product hexafluoroisopropanol, so it is desirable to avoid its formation, but in the case of unavoidable production, 1,1, A method of reducing to 1-trifluoroisopropanol is disclosed in (Patent Document 10) as a means for producing high-purity hexafluoroisopropanol.
Regarding such reaction, regarding the quality of hexafluoroacetone to be subjected to the reaction, hydrogen fluoride poisons metal catalysts such as platinum oxide in the reduction of hexafluoroacetone, so hexafluoroacetone containing hydrogen fluoride is used. In Patent Document 6, there is a description that the case must be removed in advance. On the other hand, Patent Document 11 describes that as a means for producing hexafluoroisopropanol at a low cost, it is described that hexafluoroacetone containing hydrogen fluoride is produced by reduction, but how the product can be obtained under any conditions. There is no specific description about.
Belgian Patent No. 634368 US Pat. No. 3,468,964 U.S. Pat. No. 3,702,872 JP-A-57-81424 U.S. Pat. No. 3,418,337 US Pat. No. 3,607,952 JP 58-88330 A JP 59-204142 A JP-A-1-301633 Japanese Patent Laid-Open No. 6-1884025 U.S. Pat. No. 4,314,087

  Provided is a method for catalytically hydrocracking a hexafluoroacetone / hydrogen fluoride adduct in a hydrogen fluoride solvent under mild reaction conditions to produce high purity hexafluoroisopropanol.

  As described above, many methods for producing hexafluoroisopropanol have been proposed. However, in the gas phase reaction, hot spots are likely to be formed and the catalytic activity is likely to be reduced. At this time, excessive hydrogenation may occur and by-products may be generated. On the other hand, in the liquid phase, temperature control is relatively easy. However, when anhydrous hexafluoroacetone is used as a raw material, the reaction pressure is increased due to its own pressure, and a device with high pressure resistance is required. When hydrate is used as a raw material, a relatively high temperature and a long reaction time are required. Therefore, the present invention provides a method for producing high-purity hexafluoroisopropanol that can be carried out using hexafluoroacetone as a raw material at a relatively low pressure and low temperature and that has a reduced by-product content. Is an issue.

  In the method for producing hexafluoroisopropanol by hydrogenating with hydrogen gas in the presence of a catalyst using hexafluoroacetone as a raw material, the present inventors have developed a method that produces less by-products that are difficult to separate contained in hexafluoroisopropanol. In order to develop, the reaction of hexafluoroacetone with hydrogen was investigated.

  As described above as the prior art, hydrogenation of hexafluoroacetone is performed in various states, but the form of hexafluoroacetone involved in the reaction is considered to be different from each other, and it is not clear what kind of reaction mechanism goes through. Absent. That is, when hexafluoroacetone (anhydride) is used as a reaction substrate,

In the aqueous solution, hexafluoroacetone is a trihydrate.

In hydrogen fluoride, the chemical species represented by

It is speculated that it is a chemical species represented by Therefore, since such different chemical species are involved in the hydrogenation reaction of hexafluoroacetone, the specific reaction conditions could not be easily estimated. In particular, there is very little information about the behavior of by-products.
Under such circumstances, the present inventors, regardless of which chemical species are involved, the reaction rate at which hexafluoroisopropanol is produced by increasing the reaction temperature as predicted from the technical common sense in this field. It was observed that the reaction rate was decreased by increasing the reaction temperature and lowering the reaction temperature, while the by-product was reduced in the temperature range in which sufficient reaction rate of hexafluoroisopropanol was maintained. However, it does not necessarily reduce the amount of perhydride produced, and only when the chemical species is involved in the reaction using hydrogen fluoride as a solvent in a specific temperature range, the perhydride is significantly reduced. The present invention was completed by finding that hexafluoroisopropanol substantially free of 1,1-trifluoroacetone was obtained.

The present invention is as follows.
[1] A process for producing hexafluoroisopropanol, comprising hydrogenating a hydrogen fluoride solvent by bringing hexafluoroacetone and hydrogen gas into contact with each other at −20 to 60 ° C. in the presence of a metal catalyst.
[Claim 2] The hexafluoroisopropanol according to claim 1, wherein the metal catalyst is a catalyst composed of one or more metals selected from palladium, platinum, ruthenium, rhodium and nickel, or a catalyst having the metal supported on activated carbon. Production method.
[3] The method for producing hexafluoroisopropanol according to [1], wherein the metal catalyst is a catalyst comprising ruthenium or a catalyst having ruthenium supported on activated carbon.
[Claim 4] The production of hexafluoroisopropanol according to claim 1 or 2, wherein the hexafluoroacetone is hexafluoroacetone substantially free from organic substances other than hexafluoroacetone or hexafluoroacetone / hydrogen fluoride adduct. Method.
[Claim 5] The reactor catalyst containing hexafluoroisopropanol obtained by contacting hexafluoroacetone with hydrogen gas at -20 to 60 ° C in the presence of a metal catalyst in a hydrogen fluoride solvent does not contain a metal catalyst. The hexafluoroisopropanol according to any one of claims 1 to 4, further comprising a step of obtaining a liquid component, and further, a step of separating and collecting hydrogen fluoride from the liquid component by distillation and a step of separating and collecting hexafluoroisopropanol. Production method.

  The method of the present invention surprisingly involves a decrease in the reaction rate, although the reaction is performed in a low temperature range, which is not necessarily advantageous from the viewpoint of the reaction rate, to synthesize hexafluoroisopropanol from hexafluoroacetone. In addition, since the product does not substantially contain an excessively hydrogenated by-product, the purification process can be simplified, so that hexafluoroisopropanol can be obtained in a sufficiently satisfactory yield industrially. Play.

  Hereinafter, the present invention will be described in detail.

In the specification, hexafluoroacetone may be represented as “HFA”.
In the specification, the hexafluoroacetone / hydrogen fluoride adduct may be referred to as “HFA · HF”.
In the specification, hexafluoroacetone hydrate refers to a hydrate that does not limit the number of hydration or an aqueous solution thereof, and includes hexafluoroacetone trihydrate.
In the specification, hexafluoroacetone trihydrate may be represented as “HFA · 3W”.
In the specification, hexafluoroisopropanol may be expressed as “HFIP”.

  Hexafluoroacetone can be produced by a known method. For example, it can be produced by a method of fluorinating hexachloroacetone with hydrogen fluoride in the presence of a chromium / carbon catalyst or a method of isomerizing hexafluoropropene epoxide obtained by oxidizing hexafluoropropene.

  In the present invention, hexafluoroacetone is dissolved in hydrogen fluoride, but it may be dissolved in any way, for example, gas hexafluoroacetone is absorbed in liquid hydrogen fluoride, or gas The hexafluoroacetone can be mixed with gaseous hydrogen fluoride and cooled to form a solution, or hydrogen chloride can be removed from the mixed gas of unreacted hydrogen fluoride and hexafluoroacetone obtained by the fluorination. The product can be prepared by liquefying and removing impurities. Further, it may be a mixture of hexafluoroacetone and hydrogen fluoride obtained by mixing and distilling hexafluoroacetone hydrate with hydrogen fluoride, which is also preferable in the present invention. A solution obtained by dissolving in hydrogen fluoride ”.

  In the process of completing the present invention, the inventors have found that the “solution obtained by dissolving hexafluoroacetone in hydrogen fluoride” according to the present invention has the following equilibrium in the hydrogen fluoride solution:

Hexafluoroacetone / hydrogen fluoride adduct is heptafluoroisopropanol. When excessive amount of HF coexists, it is confirmed by NMR measurement in HF that heptafluoroisopropanol exists stably without decomposition even at room temperature or higher. did.

  The ratio of hexafluoroacetone in the hydrogen fluoride solvent in the method of the present invention is not particularly limited as long as it is maintained at a stirrable level, but is 1 to 100 mol of hydrogen fluoride per 1 mol of hexafluoroacetone. 2 to 70 mol is preferable, and 3 to 50 mol is more preferable.

In the present invention, a noble metal such as palladium (Pd), platinum (Pt), ruthenium (Ru), rhodium (Rh) or a metal such as nickel can be used as a catalyst. Of these, palladium and ruthenium are particularly preferable because of their availability. The metal may be in the form of a reduced metal or a compound such as an oxide, hydroxide, or chloride, or may be a complex containing these metals, and the oxidation number of the metal is not limited. When these metals are used, they may be suspended or dissolved in a liquid-phase reaction system. However, when the catalyst is used repeatedly, it is usually supported on an appropriate carrier to use the reaction product and the catalyst. Is easy and suitable. As the carrier, metal fluorides such as activated carbon and aluminum fluoride can be adopted, and it is usually preferable to carry it on activated carbon because it is the easiest to handle and easy to obtain. The supported amount is 0.0001 to 30% by mass in terms of metal with respect to the catalyst mass, preferably 0.01 to 20% by mass, and more preferably 0.1 to 10% by mass. Specifically, a commercially available palladium-supported activated carbon catalyst of about 0.1 to 5% by mass or a ruthenium-supported activated carbon catalyst of 0.1 to 5% by mass is particularly preferable.
According to the prior art, when hydrocracking using ruthenium, the production of overreduced by-products, especially 1,1,1-trifluoroacetone, which is difficult to separate, is small, but the disadvantage is low reactivity. (Japanese Patent Laid-Open Nos. 6-184025 and 58-88330). However, in the method of the present invention using hydrogen fluoride as a solvent, when ruthenium is used as a catalyst, 1,1,1-trifluoroacetone is generated less, while exhibiting a reactivity equivalent to or higher than that of palladium. be able to.
The particle size of the catalyst is not particularly limited, but a shape suitable for suspending the catalyst is preferable, and a fine powder is used so as to facilitate uniform distribution of the catalyst in the system and increase contact between the reactant and the catalyst. It is preferable to use a catalyst in the form of a catalyst. The fine particles are also preferable for recovering the catalyst after the reaction and reusing it or separating it from the product. A known method can be adopted as a method for preparing these catalysts, and a commercially available catalyst may be used as it is or after being dried or activated.

  Although the usage-amount of a catalyst is not specifically limited, It is 0.00001-0.1 mass part with respect to 1 mass part of hexafluoroacetone (1.12 mass parts as HFA * HF), 0.0005-0 0.03 part by mass is preferable, and 0.001 to 0.01 part by mass is more preferable.

  In the method of the present invention, hydrogen fluoride is used as a solvent, but a solvent that can be dissolved in hydrogen fluoride can also be used in combination. Such can be exemplified by hexafluoroisopropanol and water which are products of the process of the present invention.

  In the method of the present invention, the reaction temperature is -20 to 60 ° C, preferably 5 to 50 ° C, more preferably 10 to 30 ° C. When the temperature is lower than -20 ° C, a special cooling facility is required and the reaction rate is reduced. When the temperature exceeds 60 ° C, the reaction rate is increased. However, the reaction product contains overreduced impurities such as 1,1,1-trifluoroacetone. This is not preferable because by-products and catalyst life may be shortened.

  In the method of the present invention, the reaction pressure is 0.05 to 5 MPa, preferably 0.1 to 1 MPa, and more preferably 0.1 to 0.5 MPa. Since the partial pressure of hydrogen fluoride as a solvent is large in the reaction temperature range, if it is less than 0.1 MPa, the partial pressure of hydrogen gas necessary to cause an efficient reduction reaction cannot be secured, and if it is 5 MPa or more, a special pressure resistance specification is required. This is not preferable because a reaction facility is required.

  The selection of suitable reaction conditions of the present invention enables a catalytic reduction reaction at an industrially satisfactory rate even at a relatively low temperature and low pressure, and the product substantially contains an excessively reduced by-product. This is an economically advantageous production method because a product with a high yield is obtained and the catalyst life is long.

  The method for producing hexafluoroisopropanol of the present invention can be carried out in any of batch, semi-batch, continuous, or flow-through formats. As the material of the apparatus, stainless steel, nickel alloy steel, silver, fluororesin, carbon, polyethylene, or a metal material lined or clad with these materials can be used.

  Hereinafter, the present invention will be described with reference to batch-type embodiments. Conditions and the like to be implemented for other implementation formats can be easily changed and determined based on the following description and common general technical knowledge in this field.

  The reactor is preferably equipped with a stirrer, but is not necessarily essential because the reaction rate is high. Usually, it is preferable to provide a heating device and / or a cooling device so that the temperature can be adjusted, and it is particularly preferable to provide a cooling device.

  The order in which the raw materials are charged into the reactor is not limited. However, after the above-mentioned “solution obtained by dissolving hexafluoroacetone in hydrogen fluoride” and the catalyst are charged, hydrogen gas is introduced while stirring and a predetermined amount is obtained. The reaction is started at a pressure of The reaction starts at a temperature of 0 ° C. or below. Moreover, in order to adjust reaction, it can also carry out by adjusting reaction temperature or hydrogen pressure, and the intensity | strength of stirring. The completion time of the reaction may be confirmed by consuming a predetermined amount of hydrogen or stopping absorption.

  After completion of the reaction, a known separation and purification method for a solution containing hydrogen fluoride and an organic substance can be applied to the reactor contents. The aqueous solution obtained by putting the reactor contents into water or ice water can be recovered directly or after neutralization and then recovered as a low boiling point component. Since the method of the present invention contains a large amount of hydrogen fluoride, without removing it immediately into the water, after removing hydrogen fluoride as much as possible from the reactor contents by distillation in advance, an aqueous solution obtained by adding it into water is used. It is preferable to recover directly as a low-boiling component by neutralization or neutralization. In any case, since the reactor content contains a catalyst, it is preferably separated and recovered by filtration or the like. Further, since the catalyst is usually reused, it is efficient and preferable to leave the catalyst in the reactor when the contents are transferred from the reactor.

  Hexafluoroisopropanol recovered from the aqueous solution by distillation can be further purified by a known distillation method. The recovered hydrogen fluoride can be used again for the reaction.

  EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The organic matter was analyzed by gas chromatography (FID detector) unless otherwise stated. In Examples, unless otherwise stated, the gauge pressure (referred to as a relative pressure with atmospheric pressure of 0 MPa) is expressed in MPa-G.

[Example 1]
A stainless steel 1 L autoclave equipped with a magnetic stirrer (inner diameter 7.4 cm inner diameter, 24 cm height) was externally cooled with ice, and 5 mass% Pd / activated carbon (manufactured by NE Chemcat, 50 mass%) as a catalyst there. 6.6 g (1% by mass) of water-containing product) and 332 g of a hexafluoroacetone hydrogen fluoride solution (a mixture of hexafluoroacetone and 8 moles of hydrogen fluoride) that had been refrigerated were weighed and added. Under ice cooling, the pressure was purged once with N ₂ and twice with H ₂ , and H ₂ pressurization was started while stirring at 500 rpm. When the internal temperature showed 9 ° C., H ₂ absorption was observed, and the internal temperature gradually increased. When the stirring was stopped, it was confirmed that the internal temperature stopped rising, and it was confirmed that the reduction reaction started from this temperature range. Thereafter, the autoclave was air-cooled from the outside at room temperature, and the hydrogenation reaction was started at an internal pressure of 1.0 MPa-G with H ₂ .

The internal temperature was 12 ° C. at the start, but gradually increased due to the heat of reaction, reached a maximum temperature of 54 ° C. after 1 hour, and thereafter the internal temperature gradually decreased. By this time, H ₂ equivalent to 98% of the equivalent had been consumed. One and a half hours after the start of the reaction, the reaction was terminated when the internal temperature became 43 ° C. and no H ₂ absorption was observed. When a small amount of hydrogen fluoride solution was extracted from the sampling tube into a polyethylene container and measured by NMR, the conversion of hexafluoroacetone to hexafluoroisopropanol was 100% and the selectivity was 100%.

  288 g of the reactor contents were put into the distillation pot of the fluororesin distillation apparatus while containing the catalyst, and hydrogen fluoride was distilled from the top of the column. The residual amount of organic matter was 136 g, of which hexafluoroisopropanol was 87% by mass and the remainder was hydrogen fluoride.

  A total of 289 g of a neutralized solution obtained by adding 18 g of sodium hydroxide and water to 126 g of the residual organic matter in the kettle was distilled with a glass single distillation apparatus, and 93 g (distillation yield 72%) of crude hexafluoroisopropanol was recovered from the top of the tower. .

  The recovered crude hexafluoroisopropanol had a hexafluoroisopropanol purity of 99.95% excluding moisture (0.9% by mass). The content of 1,1,1-trifluoroacetone (TFA) was 0.002%, and in the purification step by distillation, hexafluoroisopropanol having a purity of 99.99% or more was obtained with a distillation yield of 95%.

[Example 2]
The same operation as in Example 1 was performed except that the reaction temperature was kept at a maximum of 30 ° C. while cooling from the outside. The hydrocracking reaction was carried out using 6.4 g (1 mass%) of 5 mass% Pd / activated carbon as a catalyst and 320 g of a hydrogen fluoride solution of hexafluoroacetone (a mixture of hexafluoroacetone and 8 mol times hydrogen fluoride). Carried out.

The internal temperature was 12 ° C. at the start, but gradually increased due to the heat of reaction, reached a maximum temperature of 30 ° C. after 0.5 hours, and thereafter externally cooled to keep the internal temperature constant. By this time, H ₂ equivalent to 50% of the equivalent had been consumed. Two hours after the start of the reaction, the reaction was terminated when no H ₂ absorption was observed. When a small amount of the reactor contents were extracted from the sampling tube into a polyethylene container and measured by NMR, the conversion of hexafluoroacetone to hexafluoroisopropanol was 100% and the selectivity was 100%.

  The total amount of the reactor contents was treated in the same manner as in Example 1 to recover 132 g of crude hexafluoroisopropanol (yield 80%).

  The recovered crude hexafluoroisopropanol had a hexafluoroisopropanol purity of 99.97% excluding moisture (1.2% by mass). The content of 1,1,1-trifluoroacetone was 0.002% or less, and hexafluoroisopropanol having a purity of 99.99% or more was obtained with a distillation yield of 95% in the purification step by distillation.

[Example 3]
The same operation as in Example 1 was performed except that the reaction temperature was kept at a maximum of 30 ° C. while cooling from the outside. As a catalyst, 6.0 g (1 mass%) of 5 mass% Ru / activated carbon (manufactured by NE Chemcat, B type, 48 mass% water-containing product), hydrogen fluoride solution of hexafluoroacetone (hexafluoroacetone and 8 mol) The hydrocracking reaction was carried out using 310 g of a double hydrogen fluoride mixture.

When the internal temperature showed 0 ° C., H ₂ absorption was observed, and the internal temperature gradually increased. After 15 minutes, the maximum temperature of 30 ° C. was reached, and thereafter external cooling was performed so as to keep the internal temperature constant. By this time, H ₂ equivalent to 30% of the equivalent had been consumed. 1.5 hours after the start of the reaction, the reaction was terminated when no H ₂ absorption was observed. By this time, H ₂ equivalent to 100% of the equivalent had been consumed. When a small amount of the reactor contents were extracted from the sampling tube into a polyethylene container and measured by NMR, the conversion of hexafluoroacetone to hexafluoroisopropanol was 100% and the selectivity was 100%.

  The total amount of the reactor contents was treated in the same manner as in Example 1 to obtain 149 g (yield 91%) of crude hexafluoroisopropanol.

  The recovered crude hexafluoroisopropanol had a hexafluoroisopropanol purity of 99.97% excluding moisture (1.5% by mass). The content of 1,1,1-trifluoroacetone was 0.002% or less, and hexafluoroisopropanol having a purity of 99.99% or more was obtained with a distillation yield of 95% in the purification step by distillation.

[Example 4]
The same operation as in Example 3 was performed except that the hydrogen pressure (reactor internal pressure) was 0.2 MPa-G. As a catalyst, 6.0 g (1 mass%) of 5 mass% Ru / activated carbon (manufactured by NE Chemcat, B type, 48 mass% water-containing product), hydrogen fluoride solution of hexafluoroacetone (hexafluoroacetone and 8 mol) Hydrogenolysis reaction was carried out using 320 g of a double hydrogen fluoride mixture).

When the internal temperature showed 0 ° C., H ₂ absorption was observed, and the internal temperature gradually increased. After 20 minutes, the maximum temperature of 30 ° C. was reached, and then external cooling was performed to keep the internal temperature constant. By this time, H ₂ equivalent to 30% of the equivalent had been consumed. Two hours after the start of the reaction, the reaction was terminated when no H ₂ absorption was observed. By this time, H ₂ equivalent to 100% of the equivalent had been consumed. When a small amount of the reactor contents were extracted from the sampling tube into a polyethylene container and measured by NMR, the conversion of hexafluoroacetone to hexafluoroisopropanol was 100% and the selectivity was 100%.

  After stirring was stopped and the catalyst was allowed to settle to the bottom of the autoclave, 275 g of the reactor contents were charged from the sampling tube into the distillation pot of the fluororesin distillation apparatus. About 45 g of the reaction mixture remained at the bottom of the autoclave, including most of the catalyst. Hydrogen fluoride was extracted from the top of the distillation apparatus by distillation to obtain 145 g of organic residue in the kettle. The amount of hexafluoroisopropanol in the residual residue was 95% by weight, and the remainder was hydrogen fluoride.

  Of the remaining organic matter in the kettle, 133 g of neutralized solution of 18 g of sodium hydroxide and water was distilled with a single distillation apparatus made of glass, and 120 g (distillation yield 87%) of crude hexafluoroisopropanol was recovered from the top of the tower. .

  The recovered crude hexafluoroisopropanol had a purity of 99.99% excluding moisture (1.4% by mass). The content of 1,1,1-trifluoroacetone was 0.002% or less, and hexafluoroisopropanol having a purity of 99.99% or more was obtained with a distillation yield of 95% in the purification step by distillation.

[Example 5]
To the reaction mixture containing the catalyst remaining at the bottom of the autoclave in Example 4, 300-330 g of a hexafluoroacetone hydrogen fluoride solution (a mixture of hexafluoroacetone and 8 moles of hydrogen fluoride) was added and repeated four times. The same hydrogenolysis reaction as in Example 4 was performed. The reaction conditions and results for all 5 cases including Example 4 are shown in the table below. Even when the number of repetitions overlapped, it was found that there was almost no change in the required reaction time and yield, and the catalytic activity did not change.

[Reference example]
200 g (1.0 mol) of hexafluoroacetone hydrate (trihydrate) was placed in a 500 ml SUS-316 autoclave equipped with a stirrer, and 5% -Pd / alumina supported catalyst 1.0 weight. % And 0.3% by weight aluminum hydroxide and 0.05% by weight sodium bicarbonate were added. When the inside of the vessel was replaced with hydrogen, the temperature was raised to 100 ° C. in an oil bath, and stirring was started while maintaining the hydrogen pressure at 0.5 MPa-G (5 Kg / cm ² -G), hydrogen absorption started. After 6 hours, heating, stirring was stopped, and after cooling, analysis revealed that the reaction rate of hexafluoroacetone hydrate was 99.9%. The purity of hexafluoroisopropanol was 99.0%, 1,1,1-trifluoroacetone was 0.2%, and 1,1,1-trifluoroisopropanol (TFIP) was 0.6%. .
The crude hexafluoroisopropanol was distilled, but the purity of hexafluoroisopropanol could not exceed 99.9 because 1,1,1-trifluoroacetone exhibited an azeotropic behavior with hexafluoroisopropanol.

  According to the method of the present invention, by reacting at a relatively low temperature, hexafluoroisopropanol which is substantially free from impurities which are difficult to separate and which leads to a decrease in yield in the product is obtained, which is industrially advantageous. It can be used as a method for producing high-purity hexafluoroisopropanol.

Claims (5)

A method for producing hexafluoroisopropanol, comprising hydrogenation by bringing hexafluoroacetone and hydrogen gas into contact with each other at −20 to 60 ° C. in the presence of a metal catalyst in a hydrogen fluoride solvent. The method for producing hexafluoroisopropanol according to claim 1, wherein the metal catalyst is a catalyst composed of one or more metals selected from palladium, platinum, ruthenium, rhodium and nickel, or a catalyst having the metal supported on activated carbon. The method for producing hexafluoroisopropanol according to claim 1, wherein the metal catalyst is a catalyst comprising ruthenium or a catalyst in which ruthenium is supported on activated carbon. The method for producing hexafluoroisopropanol according to any one of claims 1 to 2, wherein the hexafluoroacetone is hexafluoroacetone substantially free of organic substances other than hexafluoroacetone or hexafluoroacetone / hydrogen fluoride adduct. A liquid component not containing a metal catalyst is obtained from the reactor contents containing hexafluoroisopropanol obtained by contacting hexafluoroacetone and hydrogen gas in a hydrogen fluoride solvent at -20 to 60 ° C. in the presence of the metal catalyst. The method for producing hexafluoroisopropanol according to any one of claims 1 to 4, further comprising a step of separating and collecting hydrogen fluoride by distillation from the liquid component and further separating and collecting hexafluoroisopropanol.