JPH06279337A - Production of 2,2,3,3,3-pentafluoro-1-propanol - Google Patents

Abstract

PURPOSE:To obtain 2,2,3,3,3-pentafluoro-1-propanol in industrial advantage and in a high yield without using highly corrosive gasses and high pressure. CONSTITUTION:3,3-dichloro-1,1,1,2,2-pentafluoropropane is oxidized to obtain pentafluoropropionyl chloride which is reduced with hydrogen in the presence of a palladium catalyst to obtain the 2,2,3,3,3-pentafluoro-1-propanol.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing 2,2,3,3,3-pentafluoro-1-propanol (hereinafter abbreviated as 5FP). 5FP is expected to be used as an intermediate for medicines, agricultural chemicals, etc. as a compound effective for introducing a perfluoroalkyl group.

[0002]

2. Description of the Related Art As a method of synthesizing 5FP, a method of synthesizing tetrafluoroethylene by adding paraformaldehyde in the presence of hydrogen fluoride (V. Weinmayr, J. Org. Chem., 2
8,492 (1963)) or a method of reducing perfluoropropionic acid with lithium aluminum hydride in ether
(DRHusted; et.al., J.Am.Chem.Soc., 75,1605 (1953))
It has been known.

[0003]

SUMMARY OF THE INVENTION In the above method,
The former is a high-pressure reaction that uses a highly corrosive gas called hydrogen fluoride, and the latter is a reaction that uses a reagent that is industrially difficult to use, such as lithium aluminum hydride.

[0004]

Means for Solving the Problems As a result of extensive studies on an efficient method for producing 5FP, the present inventor has found that 3,3-dichloro-1,1,1,2,2-pentafluoropropane (hereinafter, R -225ca) to give pentafluoropropionyl chloride, followed by hydrogenation in the presence of an activated carbon catalyst carrying palladium (Pd) or a Group 8 element containing Pd as a main component. It was found that 5FP can be synthesized in high yield by reacting.

First, the oxidation reaction in the first stage is preferably a method in which oxygen is oxidized in the presence of a small amount of water. A method of oxidizing with sulfur trioxide or fuming sulfuric acid in the presence of phosphorus halide such as phosphorus pentachloride can also be adopted, and the amount of phosphorus halide present is 1 mol of R-.
It is selected from the range of 0.01 to 1 mol with respect to 1 mol of 225ca. The reaction temperature is selected from the range of 0 to 400 ° C.

In the oxidation reaction in the presence of water, pentafluoropropionic acid is produced as a by-product together with pentafluoropropionyl chloride. The reaction rate and selectivity of this reaction are slightly affected by the amount of water. Usually, the reaction is carried out in a liquid phase or a pressurized gas phase. When almost no water is present in the liquid phase reaction, the progress of the oxidation reaction is remarkably slow, and the selectivity of pentafluoropropionyl chloride becomes low.

In the present invention, 1 mol of R-225c is used.
When about 0.5 mol or more of water is present with respect to a, the production rate of pentafluoropropionic acid is higher than that of pentafluoropropionyl chloride, and therefore it is usually 0.0
It is preferable to carry out the reaction in the presence of water selected from the range of 1 to 0.5 mol. The amount of such water depends on temperature, pressure,
As a matter of course, it may be slightly changed depending on various reaction conditions such as a reaction solvent. For example, the production ratio of pentafluoropropionic acid and pentafluoropropionyl chloride is such that the production rate of polyfluoropropionic acid increases as the conversion rate of R-225ca decreases when the amount of water is constant. .

When a reaction solvent is used, a halogenated hydrocarbon solvent such as perfluorohexane is usually preferable. The reaction temperature depends of course on the reaction pressure, but it is usually carried out in the range of 150 to 500 ° C., preferably 180
It is in the range of to 400 ° C.

The oxidation reaction of the present invention is usually carried out under pressure with oxygen. By increasing the pressure, that is, increasing the amount of oxygen, the conversion rate of R-225ca generally increases. The reaction pressure is 5 to 100 kg / cm
² is adopted, and 20-60 kg / cm ² is preferable. It is also possible to use a substance that is inert to oxygen, a reaction intermediate or a reaction product, such as oxygen diluted with nitrogen, helium, argon or carbon dioxide. The method of oxygen oxidation in the presence of water is preferable because it does not require irradiation with light or addition of a corrosive gas such as chlorine as in the conventional method, and reproducible results can be obtained.

After the amount of water exceeds a certain value, the conversion rate of R-225ca does not depend on the amount of water and mainly changes depending on the reaction temperature and the amount of oxygen. Further, as described above, increasing the amount of water leads to an increase in the selectivity of pentafluoropropionic acid. Therefore, in order to increase the yield of pentafluoropropionyl chloride among the pentafluoropropionic acid and pentafluoropropionyl chloride produced, R-225c is used while suppressing the amount of water to the minimum.
It is advantageous to ensure the conversion of a and carry out the oxidation reaction. The by-produced pentafluoropropionic acid can be easily converted to pentafluoropropionyl chloride by reaction with thionyl chloride or chlorophosphine.

The reduction of pentafluoropropionyl chloride, which is a reaction in the latter stage, is carried out in the presence of an activated carbon catalyst carrying Pd or a Group 8 element containing Pd as a main component, which is obtained by purifying a crude product of the oxidation reaction by distillation. It is carried out by reacting with hydrogen below.

The method for preparing the catalyst used in the present invention is not particularly limited, and a conventional method such as palladium chloride alone,
Alternatively, a method may be employed in which it is supported on a carrier together with another metal chloride of Group 8 element, dried, and further reduced with hydrogen. As the Group 8 elements other than Pd, Fe,
There are Co, Ni, Ru, Rh, Ir and Pt, and when added to Pd, the addition amount is preferably 0.01 to 50 parts by weight with respect to 100 parts by weight of Pd. The composite catalyst obtained by adding another group 8 element to Pd has an advantage that the heat resistance of the catalyst is higher than that of Pd alone.

If the amount of Pd or the Group 8 element containing Pd as a main component is 0.5 parts by weight or more based on 100 parts by weight of activated carbon, it can be used as an industrial catalyst, and if it is 5 parts by weight or more, the catalyst cost is high. Therefore, 0.5 to 5 parts by weight, particularly 1 to 3 parts by weight is preferable.

The activated carbon used as the carrier may be any of those prepared from raw materials such as wood, charcoal, fruit husks, coconut husks, peat, lignite and coal, but vegetable raw materials are preferable to mineral raw materials, and coconut husks are particularly preferable. Activated carbon is the best choice.
It is considered that coconut husk activated carbon has a larger surface area than other activated carbons, less impurities such as silica, and excellent acid resistance, and thus has high activity and excellent durability. The shape of the carrier is about 2 to 5 mm long charcoal, about 4 to 50 mm.
Various shapes such as crushed coal of about mesh and granular coal can be adopted, but crushed coal of about 4 to 20 mesh and formed coal are preferable.

The reaction molar ratio of pentafluoropropionyl chloride and hydrogen in this reaction is particularly important,
By setting the reaction mole number of hydrogen to pentafluoropropionyl chloride to 2 times or more, preferably 3 to 8 times, the theoretical amount of reaction, 5FP can be obtained in high yield.

The reaction temperature is 130 to 250 at atmospheric pressure.
C., preferably 150 to 200.degree. If the temperature is lower than this, the yield of 5FP is low, and if the temperature is higher than this, the heat load on the catalyst becomes large, which may lead to deterioration of the performance or cause side reactions such as thermal decomposition. The reaction pressure is not particularly limited, and it can be carried out, and normally the reaction pressure is normal pressure or self-pressure. The contact time with the catalyst may be selected from the range of usually 4 to 60 seconds, preferably 8 to 40 seconds. The reaction may be carried out by diluting it with an inert gas such as nitrogen in order to control an excessive temperature rise. The catalyst of the present invention has high durability and does not require long-term activation, but when activation is carried out, hydrogen reduction may be performed at 100 to 300 ° C, preferably 200 to 300 ° C.

[0017]

【Example】

Example 1 14 g in a 200 ml Hastelloy C autoclave
(0.068 mol) of R-225ca and 0.12 g
(0.067 mol) of water was charged and the temperature was raised to 260 ° C. Oxygen is added there and the pressure is increased to 40 kg / cm ² ,
Hold for 30 minutes. After that, the contents were collected in a trap cooled with liquid nitrogen, and the trap was immersed in a dry ice ethanol bath to remove unreacted oxygen and generated hydrochloric acid, and then the reaction crude liquid was analyzed by ¹⁹ F-NMR and gas chromatography. analyzed. As a result, the conversion rate of R-225ca is 7
The selectivity was 5%, pentafluoropropionic acid selectivity was 10%, and pentafluoropropionyl chloride selectivity was 85%.

A catalyst in which 0.5 parts by weight of Pd was supported on 100 parts by weight of crushed coconut husk activated carbon of 0.5 parts by weight of pentafluoropropionyl chloride obtained by purifying by distillation a reaction crude liquid which was reacted several times in the same manner. 100 cc was filled in a reaction tube made of Inconel 600 having an inner diameter of ½ inch and a length of 1 m, which was heated from the outside and kept at 170 ° C. and introduced at a flow rate of 0.2 mol / h, and at the same time hydrogen was introduced. Was introduced at a flow rate of 1.6 mol / h to carry out the reaction.
When the outlet gas of the reactor was analyzed by gas chromatography, the reaction rate of pentafluoropropionyl chloride was 10
The selectivity of 0% and 5FP was 99.5%.

Example 2 The reaction was carried out in the same manner as in the oxygen oxidation reaction of Example 1 except that the amount of water added was 0.25 g (0.014 mol) and 15 g of perfluorohexane was newly added. The crude liquid was similarly analyzed. As a result, the conversion rate of R-225ca was 8
The selectivity was 5%, pentafluoropropionic acid selectivity was 20%, and pentafluoropropionyl chloride selectivity was 75%. Pentafluoropropionyl chloride obtained by purifying the reaction crude liquid by distillation was reacted in the same manner as in the hydrogen reduction reaction of Example 1, and the outlet gas of the reactor was analyzed in the same manner. The reaction rate of pentafluoropropionyl chloride was shown. The selectivity of 100% and 5FP was 99.5%.

Example 3 Using pentafluoropropionyl chloride obtained in exactly the same manner as in the oxygen oxidation reaction of Example 1, 2 parts by weight of Pd was used.
After carrying out the reaction continuously for 30 days under exactly the same conditions as the hydrogen reduction of Example 1, except that the catalyst supported on 100 parts by weight of crushed 4-8 mesh coconut husk activated carbon was used, the outlet of the reactor When the gas was similarly analyzed, the reaction rate of pentafluoropropionyl chloride was 100%, 5F
The P selectivity was 99.3%.

Examples 4 to 6 The composite catalysts shown in Table 1 (all carriers are crushed coconut husks, the supported amount is 2 parts by weight with respect to 100 parts by weight of the carrier), 100 cc of inner diameter is 1/2 inch, length is 0.2 mol of pentafluoropropionyl chloride obtained in exactly the same manner as in the oxygen oxidation reaction of Example 1 was charged in a 1 m reaction tube made of Inconel 600, which was externally heated and kept at 200 ° C. / H was introduced at the same time, hydrogen was introduced at a flow rate of 1.6 mol / h at the same time, the reaction was continued for 30 days, and then the outlet gas of the reactor was similarly analyzed. The results are shown in Table 1.

[0022]

[Table 1]

[0023]

The present invention has the effect that 5FP can be industrially produced in high yield from R-225ca as a raw material without using highly corrosive gas or high pressure.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuichi Okamoto 1160 Matsubara, Hazawa-machi, Kanagawa-ku, Yokohama, Kanagawa Prefecture A-G Technology Co., Ltd. (72) Toshihiro Tanuma Matsubara Hazawa-machi, Kanagawa-ku, Yokohama Address 1160, within AG Technology Co., Ltd.

Claims (3)

[Claims] 1. 3,3-Dichloro-1,1,1,2,2-
By oxidizing pentafluoropropane,
After obtaining pentafluoropropionyl chloride, 2,2,3,3,3-penta by reacting this with hydrogen in the presence of an activated carbon catalyst supporting palladium or a Group 8 element containing palladium as a main component. Method for producing fluoro-1-propanol. 2. The method for producing 2,2,3,3,3-pentafluoro-1-propanol according to claim 1, wherein the oxidation reaction comprises oxygen oxidation in the presence of a small amount of water. 3. In the reaction with hydrogen, the number of reaction moles of hydrogen is set to twice or more the theoretical amount of reaction, 2, 2, 3,
A method for producing 3,3-pentafluoro-1-propanol.