Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Reexamination Certificate
1996-12-04
2001-11-13
Siegel, Alan (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
C570S168000, C570S169000
Reexamination Certificate
active
06316681
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method for producing 1,1,1,3,3-pentafluoropropane, which is useful as a foaming agent for foaming substances such as polyurethane, a refrigerant, and the like.
There are several conventional methods for producing 1,1,1,3,3-pentafluoropropane. For example, JP-A-Hei-6-256235 discloses a method for producing 1,1,1,3,3-pentafluoropropane from CF
3
-CClX-CF
2
Cl where X is hydrogen or chlorine, by catalytic hydrogenation. A preferable catalyst for this method is a common hydrogenation catalyst. U.S. Pat. No. 2,942,036 discloses a method of hydrogenating 1,2,2-trichloropentafluoropropane to produce 1,1,1,3,3-pentafluoropropane or 1,1,3,3,3-pentafluoro-1-propane or mixtures thereof. A catalyst for this method is palladium carried on activated carbon. These two methods mentioned hereinabove are superior in conversion and selectivity. However, these catalysts deteriorate considerably in these methods. Furthermore, it is necessary to prepare the raw material(s) of these methods in advance. Thus, these methods may not be suitable for the production of 1,1,1,3,3-pentafluoropropane in an industrial scale.
There is disclosed, in published English translation (pp. 1312-1317) of Izvestiya Akademii Nauk SSSR, Otdelenie Khimicheskikh Nauk, No. 8, pp. 1412-1418, August, 1960 (CA 55, 349f), a method for producing 1,1,1,3,3-pentafluoropropane by hydrogenating 1,1,3,3,3-pentafluoro-1-propene in the presence of Pd-Al
2
O
3
. However, it is difficult to find the raw material of this method (i.e., 1,1,3,3,3-pentafluoro-1-propene) on the market.
There is another method for producing 1,1,1,3,3-pentafluoro-propane by fluorinating 1,1,1,3,3-pentachloropropane in a liquid phase in the presence of a catalyst (see WO96/01797). However, this method is relatively low in selectivity and yield.
Unlike 1,1,1,3,3-pentalfluoropropane mentioned hereinabove, there is known another compound, 1-chloro-3,3,3-trifluoropropene, which is useful as an intermediate of medicines, of agricultural chemicals, of functional materials, and of fluorohydrocarbons. This compound is obtained, for example, by the following first to fifth processes. In the first process, 1,1,1-trifluoropropane is chlorinated to obtain, 1,1,1-trifluoro-3,3-dichloropropane, and then this compound is dehydrochlorinated by an alcoholic basic compound to produce 1-chloro-3,3,3-trifluoropropene (see J. Am. Chem. Soc., 1942, 64, 1158). In the second process, hydrogen chloride is added to 3,3,3-trifluoropropyne to produce 1-chloro-3,3,3-trifluoropropene (see J. Chem. Soc., 1952, 3490). The second process is superior in conversion and selectivity. However, it is difficult to obtain the raw material of the second process (i.e., 3,3,3-trifluoropropyne) on the market. In the third process, 3-chloro-1,1,1-trifluoro,-3-iodopropane is dehydroiodinated by alcoholic potassium hydroxide to produce 1-chloro-3,3,3-trifluoropropene (see J. Chem. Soc., 1953, 1199). In the fourth process, 3-bromo-3-chloro-1,1,1-trifluoropropane is dehydrobrominated by an alcoholic potassium hydroxide (see R. N. Haszeldine, J. Chem. Soc., 15 1951, 2495). The third and fourth processes are superior in conversion and selectivity. However, according to these processes, there is needed more than stoichiometric amount of potassium hydroxide, and it is necessary to prepare the raw materials in advance. Thus, there are problems to apply these processes to an industrial scale production. In the fifth process, 1,3,3,3-tetrachloropropene is fluorinated by hydrogen fluoride in the presence of an antimony catalyst (see U.S. Pat. No. 2,787,646). In the fifth process, there are a problem that it is difficult to obtain the raw material of the reaction on the market, and another problem that the yield of 1-chloro-3,3,3-trifluoropropene is poor for the industrial scale production.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for producing 1,1,1,3,3-pentafluoropropane, which method is free of the above-mentioned drawbacks. It is a specific object of the present invention to provide a method for producing 1,1,1,3,3-pentafluoropropane with a high yield, which method is suitable for an industrial scale production.
It is another object of the present invention to provide a method for easily continuously producing 1,1,1,3,3-pentafluoropropane, in which method there is used a raw material of 1-chloro-3,3,3-trifluoropropene that can easily be obtained on the market.
According to a first aspect of the present invention, there is provided a first method for producing 1,1,1,3,3-pentafluoropropane, comprising a step of fluorinating 1-chloro-3,3,3-trifluoropropene in a liquid phase by hydrogen fluoride in the presence of an antimony compound as a catalyst. According to the first method, 1,1,1,3,3-pentafluoropropane can be produced with an high yield, due to the use of an antimony compound as a catalyst for the fluorination.
According to a second aspect of the present invention, there is provided a second method for producing 1,1,1,3,3-pentafluoropropane, comprising a step of fluorinating 1-chloro-3,3,3-trifluoropropene in a gas phase by hydrogen fluoride in the presence of a fluorination catalyst According to the second method, 1,1,1,3,3-pentafluoropropane can easily continuously be produced. Therefore, the second method is useful for an industrial scale production thereof. The raw material of the first and second methods, 1-chloro-3,3,3-trifluoropropene, can easily be obtained on the market.
According to the present invention, there is provided a third method for producing 1-chloro-3,3,3-trifluoropropene, which is a raw material of the first and second methods. The third method comprises a step of reacting 1,1,1,3,3-pentachloropropane with hydrogen fluoride in a gas phase in the presence of a fluorination catalyst. A raw material of the third method, 1,1,1,3,3-pentachloropropane, is easily obtained by one of the after-mentioned conventional methods. Furthermore, yield of 1-chloro-3,3,3-trifluoropropene is high, and therefore the third method is useful as an industrial-scale method for producing 1-chloro-3,3,3-trifluoropropene
According to the present invention, the third method may be combined with either of the first and second methods, thereby to produce 1,1,1,3,3-pentafluoropropane from 1,1,1,3,3-pentachloropropane.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In accordance with the first aspect of the present invention, there will be described in detail the above-mentioned first method for producing 1,1,1,3,3-pentafluoropropane, as follows.
In the first method, the step may be conducted by a continuous operation, a batch operation, or a half-batch operation in which only the reaction product is continuously removed from a reactor. Hereinafter, the description of the first method will be concerned mainly with a batch operation. If the first method is conducted by another operation, it is optional to modify the reaction condition(s) of a batch operation, which will be described hereinafter.
It is known to use an antimony catalyst for fluorinating halogenated hydrocarbons in a liquid phase by hydrogen fluoride. It is generally assumed that this antimony catalyst under its activated condition during the fluorination takes a form of a halogenated antimony compound represented by a formula of SbFaXb where X is a halogen, “a” and “b” are numbers each ranging from 0 to 5, and the total of “a” and “b” equals to 5. Thus, it is assumed that an antimony compound used as a catalyst in the first method also takes a form of such halogenated antimony compound, regardless of the form of the original antimony compound, when the antimony compound is under its activated condition during the fluorination. A halogenated antimony(III) compound, which is in a non-activated condition, is easily oxidized to another halogenated antimony(V) compound, which is in an activated condition, by chlorine, bromine or fluorine. Therefore, an antimony compound that is introduced as a catalyst into the reaction system of the first method is not limited to an antim
Gotoh Yoshihiko
Hibino Yasuo
Sakyu Fuyuhiko
Tamai Ryouichi
Yoshikawa Satoshi
Central Glass Company Limited
Crowell & Moring LLP
Siegel Alan
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