JPS5888330A - Production of 1,1,1,3,3,3-hexafluoro-2-propanol - Google Patents

Abstract

PURPOSE:The hydrogenation of hexafluoroacetone is carried out in the presence of a rhodium catalyst to produce in high yield the titled substance that is used as a surface active agent, emulsifier, polymer solvent, synthetic intermediate of fluorine-containing compounds and intermediate of inhalation anesthetic. CONSTITUTION:The titled substance is obtained by hydrogenation of hexafluoroacetone in the presence of a rhodium catalyst such as reduced rhodium, rhodium oxide, rhodium hydroxide, or rhodium chloride. As a catalyst, 0-valent rhodium is effective and reduced rhodium is preferred. The catalyst is generally in the form of rhodium on a support (such as activated carbon or alumina)[the content of rhodium is 0.5-10wt% based on the support (calculated as metallic rhodium)] and the reaction is preferably carried out in a gaseous or liquid system. The amount of the catalyst ued is 0.001-0.1wt% based on the starting material calculated as metallic rhodium and reaction conditions are 20-100 deg.C, 0.5- 30 atmospheric pressure in the hydrogen partial pressure and 1min to 500hr in reaction time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention consists of reducing hexafluoroacetone-〇FgCOCFm (hereinafter abbreviated as HFA) with hydrogen in the presence of a specific catalyst 1, 1.1.3.3.3- Hexafluoro-2-propanol CFs OHOHCFg
(hereinafter abbreviated as HFIPA).

HFIPA is useful as a surfactant, emulsifier, or solvent for some polymers. Also, HFIPA
is also valuable as an intermediate for the synthesis of various fluorine-containing compounds. For example, using HFIPA as a starting material, 2) hydrogen of the alcohol group of iF-PA is converted into methyl, fluoromethyl,
Ethyl-substituted ethers have also been proposed as inhalation anesthetics.

Various methods have been known for producing I (FIPA), and a production method consisting of reducing HFA with hydrogen in the presence of a catalyst has also been proposed. Catalyst, Pd-based catalyst, 0u-
(Although 3rzOs-based catalysts are known, they all have an insufficient conversion rate of the raw material HFA, and the target HFI
It has disadvantages such as low yield of PA, high reaction temperature and high reaction pressure, impurities in raw materials and reaction by-products inhibiting reaction activity, and poor catalyst durability.

That is, U.S. Pat. No. 3,418,337 discloses a liquid phase reaction using a PTO catalyst;
Requires extremely high reaction pressure. Furthermore, U.S. Patent No. 3,607,952 discloses a method in which the liquid phase reaction proceeds under a lower reaction pressure using the same <pto catalyst, but HFIPA, which is the desired product, is used at the beginning of the reaction. It is necessary to add more to the system. In addition, West German patent 2. ] l According to Publication No. 3.551, Pd
/I(E,TPA) has been obtained by a liquid phase reaction using a catalyst prepared by treating activated carbon with an alkali such as Na2COs, but the preparation of such a catalyst is complicated and cumbersome.

On the other hand, Ou-Orgys-Ca'F catalyst (
Special Publication No. 39-8210), Pd/A1!0! Catalysts (US Pat. No. 3,468,964) and Pd/C catalysts (Japanese Patent Publication No. 48-21925) are known.
It has disadvantages such as requiring a high reaction temperature and being unsatisfactory in catalyst activity and durability.

The present inventor has conducted various researches in order to resolve these difficulties and provide an excellent catalyst for the catalytic reduction reaction of FA to HFIPA using hydrogen, and has obtained the following new findings. The present invention was completed based on the knowledge that rhodium catalysts have high activity for this reduction reaction and are also excellent in terms of the production rate of the target HF engineered PA, as well as durability, impurities, etc. The present invention is excellent in that it is not easily influenced by
The present invention provides a novel method for producing HFXPA, which is characterized by reducing HFA with hydrogen in the presence of a rhodium catalyst.

In the present invention, it is important to use a rhodium catalyst. Examples of the rhodium catalyst include reduced rhodium, or rhodium compounds such as rhodium oxide, rhodium hydroxide, and rhodium chloride, and may also be complexes containing rhodium, and the oxidation number of rhodium is not particularly limited.

Among them, zero-valent rhodium is effective, and reduced rhodium is a preferable example. Further, reduced rhodium may be present from the beginning of the reaction, or may be present transiently during the reaction. When such a rhodium catalyst is used, for example, in this reduction reaction in a liquid phase reaction system, it may be suspended or dissolved in the reaction system as it is, but it is usually supported on a suitable carrier and used in a gas phase reaction system or in a gas phase reaction system. It is convenient to use in liquid phase reaction systems. As the carrier, activated carbon, alumina, silica, norica alumina, magnesia, asbestos, diatomaceous earth, other oxides, sulfates, carbonates, fluorides, etc. can be used, and activated carbon and alumina are particularly convenient. The supported rhodium content in the supported catalyst is not particularly limited, but is 0.1% relative to the carrier weight in terms of metallic rhodium.
~20% by weight, especially 05-10% by weight is preferred. The particle size of the carrier is not particularly limited, but when using a liquid phase reaction system with a suspended catalyst, it is important to make it easier to homogenize the distribution of the catalyst within the system and to prevent contact between the reactants and the catalyst. As such, it is generally preferred to use a finely divided carrier.

When adopting a gas phase reaction system or liquid phase reaction system using a fixed bed catalyst, it is necessary to conduct at least one visit so that the catalyst can be retained in the catalyst layer and the fluid flow resistance can be maintained within an appropriate pressure loss range. It is generally preferred to use a carrier having a particle size of .

Furthermore, a reaction using a fluidized bed method can also be employed using a catalyst of an appropriate particle size.

For the preparation of such a rhodium catalyst, various well-known and well-known methods including a supporting method can be employed, and various commercially available rhodium catalysts can also be used. It is possible to use a pre-prepared catalyst, or to use it after appropriate activation treatment.

HFA used in the present invention can be prepared by various methods, but it can be used as a raw material in the present invention even if it is contaminated with impurities associated with the preparation. For example, it may be HFA obtained from hexachloroacetone and therefore included as an impurity in monochloropentafluoroacetone, or directly from hexafluoropropene (hereinafter HF'P, !: abbreviation) or hexafluoropropene epoxide. (Thus) TFP, hexafluoropropene epoxide, pentafluoropropionylfluoritonatra may be HFA containing as an impurity. Furthermore, other fluorine-containing or chlorine-containing compounds may be included as impurities.

It goes without saying that products in which these impurities are reduced or removed by appropriate purification methods may also be used.

The present invention may be carried out by either a liquid phase method or a gas phase method. When carrying out the present invention by a liquid phase method, an aging medium or a diluent may or may not be used. Solvents or diluents that can be used include HFIPA, CF3CH20
H, methanol, ethanol, cyclohexanol nato alcohols, CF2CIC! PCI! , 0F2
Examples include halogenated hydrocarbons such as C12 and RFP, hydrocarbons such as heptane and cyclohexane, and nytails such as hexafluoropropene epoxide and dioxane.
It is preferable to use A as a solvent. It is rather unsuitable to use water as a solvent or to mix it in, since HFA reacts with water and becomes less susceptible to reduction (CFm), 0 (OH). Reaction conditions such as reaction temperature and reaction pressure are not particularly limited, and conventionally known or well-known conditions can be employed. For example, in a batch or semi-batch liquid phase reaction in which the entire amount of raw material HFA is charged at the start of the reaction, the reaction pressure is preferably 05 to 70 atm, especially 1 to 50 atm, including the hydrogen partial pressure, and the reaction temperature is 0. ~20
0°C, especially 20-100°C is preferred. The amount of catalyst used is 0.000 relative to the weight of HFA supplied in terms of gold rhodium.
It is preferably 1 to 1 wt%, particularly 0.001 to 1 wt%. The reaction time may be, for example, about 1 minute to 500 hours, although it depends on other reaction conditions such as reaction temperature or operating conditions. Hydrogen may be supplied alone or mixed with an inert gas such as nitrogen.Hydrogen partial pressure is 0.3
~50 atm, especially 05 to 30 atm is preferred. The total amount of hydrogen to be supplied should be equal to or more than the mole of raw material I (FA), and there is no problem even if hydrogen is supplied in excess.Also, by supplying a smaller number of moles of hydrogen than the number of moles of thick phase HFA, it is possible to increase the amount of hydrogen to HFIPA. It is also possible to keep the conversion rate at an appropriate value of 100 or less, or to adjust the reaction rate and reaction temperature as appropriate.The total amount of hydrogen supplied may be supplied to the reaction system at once at the start of the reaction, or the reaction progresses. It may be divided into a plurality of times and may be supplied continuously to and C'.

When the total amount of hydrogen is supplied at once at the start of the reaction,
The reaction pressure and hydrogen partial pressure are preferably within the above-mentioned pressure range immediately after hydrogen supply, but may be lower than this pressure range at the end of the reaction. This is L! 11. Hydrogen is consumed as the reaction progresses, HFA with high vapor pressure decreases,
This is because HFIPA, which has a low vapor pressure, increases, and as a result, both the reaction pressure and the hydrogen partial pressure decrease. This point also applies to the case where hydrogen is divided into multiple portions and supplied intermittently. In addition, a flow-through liquid phase reaction in which hydrogen, HFA, and a solvent or diluent are continuously supplied to the reaction system as necessary, or a circulating liquid phase reaction in which part or all of the raw materials are recycled and supplied to the reaction system. Reactions and the like may also be employed as appropriate.

In the above description, a liquid phase reaction refers not only to cases where a clear liquid phase exists in the reaction system, but also cases where there is a condensed liquid phase, that is, a critical γ blackness where it is impossible to clearly distinguish between a gas phase and a liquid phase. This also includes cases where the substance is in the state of a substance at a temperature above that temperature.

When carrying out the present invention by a gas phase method, a suitable example is a gas phase flow reaction method in which hydrogen and HFA are continuously passed through a fixed catalyst bed. Reaction gases include inert gases such as nitrogen and HF.
At the same time, diluents such as P, CFzOICFOlz,
Alternatively, it is okay to communicate intermittently. The reaction conditions are not particularly limited, but the reaction temperature is preferably 50 to 400°C, particularly 150 to 300°C, and the reaction pressure is 0.5 to 400°C.
A pressure of 10 atm, especially 1 to 4 atm is preferred. The molar ratio of hydrogen to HFA is preferably 1 or more, particularly preferably in the range of 1.5 to 5. For example, when using a supported catalyst, the contact time can be changed depending on the rhodium loading ratio, etc.
Seconds, especially 1 to 100 seconds are preferred. In addition, since this reduction reaction is an exothermic reaction, it is often effective to prevent or suppress the catalyst temperature from rising excessively by passing an inert gas or other diluent along with it, as it often extends the life of the catalyst. However, for similar purposes, it is also possible to use a method in which a catalyst is mixed with an inert or low-activity packing. Note that the reaction method is not limited to a fixed bed reaction method, and a moving bed method or a fluidized bed method may also be adopted as appropriate.

Regardless of whether the method is a liquid phase method or a gas phase method, it is also possible to reactivate the catalyst once subjected to the reaction by hydrogen treatment, vacuum degassing treatment, or other appropriate methods.

Thus, according to the method of the present invention, IFIPA (by hydrogen reduction of HFA'IO) can be obtained with high activity and high yield under convenient reaction conditions, and the catalyst has excellent durability or is not easily affected by impurities. However, embodiments of the present invention will be described in detail.

It goes without saying that the present invention is not limited in any way by this explanation.

Example 1 A vertical cylindrical pressure-resistant vessel made of SUS with a content of approximately 50 ml and having a sensitometer, an inlet, and a needle pulp was filled with a metal rhodium/activated carbon fine powder supported catalyst (Nippon Enkerno Co., Ltd.) with a rhodium loading rate of 2 wt%. (manufactured by Rudo Corporation). , 2.2 and Tef!
After a coated stirring bar was added, the inside of the system was vacuum degassed at room temperature.

Next, this pressure-resistant container was heated to 120°C for about 30 minutes.
Vacuum degassing was continued for a minute to remove water and the like adsorbed on the activated carbon carrier. The pressure vessel was then cooled in a dry ice/acetone bath while being closed, connected to an HFA vessel, and 252 crude HIII'A was introduced. This crude HFA
The purity was about 9-0% and the main impurity was RFP. Next, this pressure-resistant container was connected to a hydrogen cylinder, placed in a water bath, and heated to about 65° C., and at the same time, the contents of the pressure-resistant container were stirred using a magnetic stirrer.

The pressure was 29 atmospheres. While maintaining the bath temperature at this temperature and continuing to stir, hydrogen was introduced to bring the pressure to 34 atmospheres. After the pressure immediately rose to 35 atmospheres, approximately 1
After a few minutes, the pressure dropped to 30 atmospheres. Hydrogen was introduced again to bring the pressure to 35 atmospheres. After the pressure rose to 36 atmospheres, it decreased to 29 atmospheres about 1.5 minutes later. In this way, each time the pressure decreased to 29 to 30 atm, hydrogen was introduced intermittently to bring the pressure to 35 to 36 atm, and this was repeated for a total of 11 times in one hour after the first hydrogen introduction. Hydrogen can be introduced. As the reaction time progressed, the rate of pressure drop slowed, and therefore the interval between introductions became longer as the number of introductions increased. After 1 hour, the pressure container was removed from the walk bath and cooled in a dry ice/acetone bath.
The remaining hydrogen was slowly released. Next, the system was thawed with hot water while being closed, and dissolved hydrogen, unreacted HFA, HFP, etc. were slowly released while being cooled with ice water, and then the pressure container was opened and the product was recovered.

When analyzed by F-NMR and gas chromatograph, the obtained product was mostly HF I PA,
The molar yield of HFIPA was 95% based on the net HFA fed.

Comparative Example 1 A liquid phase catalytic reduction reaction of crude HFA with H2 was carried out in substantially the same manner as in Example 1, except that the catalyst was mainly changed. The results are shown in the following table. In all cases, the pressure drop rate was slower than in Example 1, and almost no pressure drop was observed after the initial introduction of hydrogen once or twice, except in the case of the palladium/activated carbon catalyst. However, in the case of the palladium/activated carbon catalyst, hydrogen could only be supplied six times in one hour of reaction time.

×Metal Pd/Activated carbon fine powder catalyst (Pa loading rate 2 wt%
) was treated with NazOOs aqueous solution to reduce the Na loading rate to 0.4.
A solid catalyst.

Example 2 Rhodium compatibility ratio is 2 in a U-shaped SUs reaction tube with an inner diameter of 8 mm.
It was filled with wt% metal rhodium/granular activated carbon (10 to 20 mesh) supported catalyst (manufactured by Nippon Enkelhardt Co., Ltd.) 10-. After replacing the inside of the system with N2, the reaction tube was heated to 180℃.
It was heated in the soil temperature of 'C. Crude HF similar to that used in Example 1 after pretreatment with nitrogen and then hydrogen.
A and hydrogen each from 10 to 5 d/1niR
(calculated as room temperature, the same applies hereinafter), and the mixture was mixed at a flow rate of approximately 307/xi and supplied to the reaction system. The reaction tube outlet gas is 2
It was discharged to the vent via a tiered ice-water trap. Much of the condensate was trapped in the first stage ice-water bath trap, and virtually all of it was HF'IPA. When the trap was replaced every hour and the condensate was analyzed, the molar yield of HF processed PA from 3.0 to 3 hours was essentially 100 cm, and the molar yield of HFIPA for 1 hour was 98 cm. There it was.

Comparative Example 2: Reduction of crude HFA in almost the same manner as in Example 2, except that the catalyst was replaced with a metal palladium/granular activated carbon (10 to 20 mesh) supported catalyst (manufactured by Nippon Engelheide Co., Ltd.) with a palladium loading rate of 2 wt%. The reaction was carried out. HF from 0 to 3 hours
The IPA molar yield was 90 HFI for the next 1 hour.
The PA molar yield was 75%. Moreover, almost the same reduction reaction was carried out using a high purity reagent HFA contained in a small cylinder instead of the crude HFAO. 'HF work P from 0 to 3 hours
A mole yield was 84-94. This result shows that the palladium/activated carbon catalyst has considerably high activity and that HFA
Although it is relatively unaffected by impurities in the catalyst, rhodium-based catalysts have superior activity and durability, and are not affected by impurities.

Comparative Example 3 The catalyst was replaced with a metal palladium/granular active A1201 (10-20 mesh) catalyst with a palladium loading rate of 0.5 wt% (manufactured by Nippon Engelhard), and the reaction temperature was increased to 12
The reduction reaction of crude HFA and high purity reagent HFA was carried out in substantially the same manner as in Example 2, except that the temperature was changed to 0°C. HFIP from 0 to 2 hours when using high purity reagent HFA
The A molar yield was 92%, and when crude HFA was used, the HF-processed PA molar yield from 0 to 2 hours was 5 H or less. This result shows that the palladium/activated alumina catalyst is
This shows that it is greatly influenced by the impurities in A. Similarly, copper-chromium oxide catalyst (reaction temperature 20
0℃), nickel-diatomaceous earth catalyst (reaction temperature 150℃), nickel-diatomaceous earth catalyst (reaction temperature 150℃)
°C) is also extremely affected by impurities in HFA, and H
The molar yield of FIPA is 90-95 for the high purity reagent HFA.
%, whereas for crude HFA it was less than 60%.

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Claims (1)

[Claims] 1. J, characterized in that hexafluoroacetone is reduced with hydrogen in the presence of a rhodium catalyst, 1°], 3.3
．． Method for producing 3-hexafluoro-2-propatol