Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Reexamination Certificate
1996-11-20
2001-05-22
Kight, John (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
C570S163000, C570S165000, C570S167000, C570S168000
Reexamination Certificate
active
06235951
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-propene 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-pentafluoropropane by fluorinating 1,1,1,3,3-pentachloropropane in a liquid phase in the presence of a catalyst (see WO96101797). 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, 1,1,1,1-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-triluoropropene (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., 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, which method is high in selectivity and yield.
According to a first aspect of the present invention, there is provided a first method for producing 1,1,1,3,3-pentafluoropropane, comprising steps of;
(a) adding hydrogen fluoride to 1-chloro-3,3,3-trifluoropropene in the presence of an addition catalyst to obtain 1,1,1,3-tetrafluoro-3-chloropropane; and
(b) disproportionating said 1,1,1,3-tetrafluoro-3-chloropropane into said 1,1,1,3,3-pentafluoropropane and 1,1,1-trifluoro-3,3-dichloropropane, in the presence of a disproportionation catalyst.
The first method of the present invention is a useful method for producing 1,1,1,3,3-pentafluoropropane in an industrial scale, because its steps (a) and (b) are respectively superior in selectivity and yield.
According to the first aspect of the present invention, there is further provided a first modification of the first method, for producing 1,1,1,3-tetrafluoro-3-chloropropane, comprising a step of adding hydrogen fluoride to 1-chloro-3,3,3-trifluoropropene in the presence of an addition catalyst.
According to the first aspect of the present invention, there is still further provided a second modification of the first method, for producing 1,1,1,3,3-pentafluoropropane, comprising a step of disproportionating 1,1,1,3-tetrafluoro-3-chloropropane into said 1,1,1,3,3-pentafluoroprop ane and 1,1,1-trifluoro-3,3-dichloropropane, in the presence of a disproportionation catalyst.
According to a second aspect of the present invention, there is provided a second method for producing 1-chloro-3,3,3-trifluoropropene, comprising a step of reacting 1,1,1,3,3-pentachloropropane with hydrogen fluoride in a gas phase in the presence of a fluorination catalyst. The raw material of the second 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 second method is useful as an industrial-scale method for producing 1-chloro-3,3,3-trifluoropropene.
According to the present invention, the first and second methods bay be combined, 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. The relevant parts of the following descriptions of the first method also apply to the above- mentioned first and second modifications of the first method.
In the first method, each of the steps (a) and (b) may be conducted by a batch operation or by a continuous operation in which the reactants are continuously supplied to a reactor and in which the reaction product is continuously removed therefrom. Of these, the continuous operation is preferably taken.
In the first method, the addition catalyst used in the step (a) is preferably at least one compound selected from antimony halides, tin halides, titanium halides and boron halides. For instance, it is assumed that boron trifluoride and hydrogen fluoride form a coordinated complex therebetween. Thereby, the degree of ionic character of H-F bond is increased. With this, the addition catalyst is assumed to catalyze addition reactions between olefins and hydrogen fluoride (see A. L. Henne et al., J. Am. Chem. Soc., 1948, 70, 758). Examples of antimony halides to be used as the addition catalyst are antimony pentachloride, antimony pentabromide, antimony pentaiodide, antimony pentafluoride, antimony trichloride, antimony tribromide, and antimony triiodide Of these, antimony pentachloride and antimony trichloride are preferable examples. Examples of tin halides to be used as the addition catalyst are tin tetrachloride, tin tetrabromide, tin tetraiodide and tin tetrafluoride. Of these, tin tetrachloride is the most preferable example. Examples of titanium halides to
Gotoh Yoshihiko
Hibino Yasuo
Sakyu Fuyuhiko
Tamai Ryouichi
Yoshikawa Satoshi
Central Glass Company Limited
Covington Raymond
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Kight John
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