Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Reexamination Certificate
1999-11-05
2001-04-17
Siegel, Alan (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
C570S166000, C570S167000, C570S168000, C570S169000
Reexamination Certificate
active
06218586
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to methods for preparing perhalogenated five-membered cyclic compounds, such as chlorofluorocyclopentenes and chlorofluorocyclopentanes, particularly 1,2-dichlorohexafluorocyclopentene, 1,1-dichlorooctafluorocyclopentane and the like, which are useful as intermediates for heptafluorocyclopentane and as intermediates for various fluorine-containing compounds. Heptafluorocyclopentane is useful as a fluorine-containing detergent, a fluorine-containing drying solvent, or the like.
It is known that hydrogen-containing fluorinated cyclopentanes are produced at first by fluorinating chlorinated cycloalkenes corresponding to the fluorinated cyclopentanes to obtain vicinally chlorinated fluorocyclopentene derivatives, and then by fluorinating and hydrogenating these derivatives. It is known that vicinally chlorinated fluorocyclopentene derivatives are produced by a first method, in which perhalogenated cycloolefins are used as starting materials, or a second method, in which perhalogenated cycloconjugated dienes are used as starting materials. In either of these first and second methods, the fluorination can be conducted by either a liquid phase process or a gas phase process. This liquid phase process can be conducted by using antimony trifluoride or hydrogen fluoride as a fluorination agent, in the presence of an antimony halide as a fluorination catalyst. Antimony halide is, however, highly corrosive. Furthermore, if hydrogen fluoride is used as the fluorination catalyst in an industrial scale production, the reaction pressure may become as high as 10-30 kg/cm
2
. This may cause some limitations in the selection of devices. The gas phase process can be conducted by using hydrogen fluoride as a fluorination agent, in the presence of a fluorination agent selected from various substances. U.S. Pat. No. 3,178,482 discloses a method for producing 1,2-dichlorohexafluorocyclopentene by fluorinating trichloropentafluorocyclopentene in the presence of activated carbon as catalyst. U.S. Pat. No. 3,258,500 discloses a method for producing 1,2-dichlorohexafluorocyclopentene by fluorinating 1,2,4-trichloropentafluorocyclopentene in the presence of chromium oxide (CrO
3
) as catalyst. DE 1543015 discloses a method for producing 1,2-dichlorohexafluorocyclopentene by fluorinating octachlorocyclopentene in the presence of a Cu/Al oxide.
It is disclosed in J. Am. Chem. Soc., 67, 1235 (1945) to react 1,2-dichlorohexafluorocyclopentene with chlorine at 70° C. under the UV light irradiation in order to saturate its double bond with a halogen except fluorine. It is disclosed in J. of Fluorine Chem., 49(3), 385-400 (1990) to produce 1,2 dichlorooctafluorocyclopentane by fluorinating 1,2-dichlorohexafluorocyclopentene at 25° C. in the presence of vanadium pentachloride. Japanese Patent First Publication JP-A-8-333285 discloses a method for producing 1,2-dichlorohexafluorocyclopentene at first by reacting hexachlorocyclopentadiene with chlorine in the presence of antimony trichioride, thereby to respectively convert the hexachlorocyclopentadiene and antimony trichloride to octachlorocyclopentene and antimony pentachloride, and then by adding hydrogen fluoride thereto. JP-A-3-151336 discloses a method for fluorinating hexachlorocyclopentadiene in a gas phase in the presence of chlorine and hydrogen fluoride using a Mg/Bi/Fe oxide as a catalyst, thereby to obtain 1,2-dichlorohexafluorocyclopentene. It is, however, necessary to previously fluorinate such oxides, which are disclosed in JP-A-3-151336 and U.S. Pat. No. 3,258,500, if they are used as fluorination catalysts. This fluorination takes a long time, and it is difficult to achieve a complete fluorination.
One of the aimed products of the invention, that is, 1,1-dichlorooctafluorocyclopentane, is a useful compound, since it can easily be reduced by hydrogen to beptafluorocyclopentane. A method for producing 1,1-dicholorooctafluorocyclopentane is disclosed in U.S. Pat. No. 5,416,246. In this method, it is produced through isomerization of 1,2-dichlorooctafluorocyclopentane by passing 1,2-dichlorooctafluorocyclopentane, together with hexafluoropropene, through chlorofluorinated aluminum heated at 130° C.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method for preparing a perhalogenated five-membered cyclic compound, such as 1,2-dichlorohexafluorocyclopentene or 1,1-dichlorooctafluorocyclopentane, which method is appropriate for the production of the same in an industrial scale.
According to the present invention, there is provided a method for preparing a fluorinated product that is a first perhalogenated five-membered cyclic compound. This method comprises reacting in a gas phase a starting material that is a second perhalogenated five-membered cyclic compound (e.g., perchlorocyclopentadiene or perchlorocyclopentene) having at least one unsaturated bond, at substantially the same time with chlorine and hydrogen fluoride, in the presence of a fluorination catalyst comprising an activated carbon optionally carrying thereon a metal compound, thereby to decrease the number of said at least one unsaturated bond and to increase the number of fluorine atoms of said second compound. By this reacting, it becomes possible to obtain the first perhalogenated five-membered cyclic compound with a high yield, such as chlorofluorocyclopentenes and chlorofluorocyclopentanes, particularly 1,2-dichlorohexafluorocyclopentene and 1,1-dichlorooctafluorocyclopentane. In this method, it is not necessary to use a special pressure-tight reactor nor have many reaction steps. Furthermore, the above fluorination catalyst can easily be prepared and is stable for a long time in activity.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the invention, the fluorinated product, that is, the first perhalogenated five-membered cyclic compound, may be a first perhalogenated cyclopentene represented by the general formula C
5
C
1
D
F
8-D
, where D is an integer of 0-7, or a perhalogenated cyclopentane represented by the general formula C
5
Cl
E
F
10-E
, where E is an integer of 0-9. Furthermore, the starting material, that is, the second perhalogenated five-membered cyclic compound, may be a perhalogenated cyclopentadiene represented by the general formula C
5
Cl
A
F
6-A
, where A is an integer of 0-6, or a second perhalogenated cyclopentene represented by the general formula C
5
Cl
B
F
8-B
, where B is an integer of 0-8. As stated above, the fluorinated product is less than the starting material in the number of unsaturated bonds in the molecule.
As mentioned above, the fluorinated product is greater than the starting material in the number of fluorine atoms in the molecule. Therefore, in case that the starting material is the perhalogenated cyclopentadiene represented by the general formula C
5
Cl
A
F
6-A
, where A is an integer of 0-6, and the fluorinated product is the first perhalogenated cyclopentene represented by the general formula C
5
Cl
D
F
8-D
, where D is an integer of 0-7, A and D are such that the expression D<(2+A) is satisfied. Similarly, in case that the starting material is the perhalogenated cyclopentadiene represented by the general formula C
5
Cl
A
F
6-A
, where A is an integer of 0-6, and the fluorinated product is the perhalogenated cyclopentane represented by the general formula C
5
Cl
E
F
10-E
, where E is an integer of 0-9, A and E are such that the expression E<(4+A) is satisfied. Similarly, in case that the starting material is the second perhalogenated cyclopentene represented by the general formula C
5
Cl
B
F
8-B
, where B is an integer of 0-8, and the fluorinated product is the perhalogenated cyclopentane represented by the general formula C
5
Cl
E
F
10-E
, where E is an integer of 0-9, B and E are such that the expression E<(2+B) is satisfied.
As mentioned above, the starting material is reacted with chlorine and hydrogen fluoride at substantially the same time. This timing of “at substantially the same time” means that the reaction is condu
Imura Hideaki
Kanai Masatomi
Komata Takeo
Takada Naoto
Central Glass Company Limited
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Siegel Alan
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