PROCESS FOR PRODUCING HALOGENATED BUTENE AND BUTANE

Abstract: A process for industrially producing at least one halogen compound selected from the group consisting of 1,1,1,4,4,4-hexafluoro-2,3-dichlorobutane, 1,1,1,4,4,4-hexafluoro-2-chloro-2-butene, 1,1,1,2,4,4,4-hepta-fluoro-2-butene and 1,1,1,2,2,4,4,4-octafluorobutane by the vapor-phase reaction of 1,1,2,3,4,4-hexachloro-1,3-butadiene with hydrogen fluoride in the presence of a fluorination catalyst.

Description: The present invention relates to a method for preparing halogenated butane and butane. Particularly, it relates to a method for preparing at least one halogenated compound selected from the group consisting of 1,1,1,4,4,4-hexafluoro-2,3-dichlorobutane, 1,1,1,4,4,4-hexafluoro-2-chloro-2-butene, 1,1,1,2,4,4,4-heptafluoro-2-butene and 1,1,1,2,2,4,4,4-octafluorobutane. Related Art 1,1,1,4,4,4-Hexafluoro-2,3-dichlorobutane, 1,1,1,4,4,4-hexafluoro-2-chloro-2-butene and 1,1,1,2,4,4,4-heptafluoro-2-butene are useful as industrial chemicals and as an intermediate for medicines and agricultural chemicals. In addition, these materials can be a raw material to prepare 1,1,1,2,2,4,4,4-octafluorobutane which can be prepared by adding hydrogen fluoride (HF) to these materials, and which substitutes for HCFC and is used as a foaming agent, a detergent and a heating medium. 1,1,1,4,4,4-Hexafluoro-2,3-dichlorobutane, 1,1,1,4,4,4-hexafluoro-2-chloro-2-butene and 1,1,1,2,4,4,4-heptafluoro-2-butene can be reduced to prepare 1,1,1,4,4,4-hexafluorobutane which is used as the same applications as those of these materials. It is known that 1,1,1,2,4,4,4-heptafluorobutene can be prepared by fluorinating hexachlorobutadiene with KF. However, this method is commercially unsuitable, since a reaction procedure is complex, a treatment of KCl produced after the reaction is necessary due to the use of KF, and the cost is high. It is also known that 1,1,1,4,4,4-hexafluoro-2-chloro-2-butene can be prepared by fluorinating hexachloro-1,3-butadiene with HF in the presence of SbCl 5 . However, the antimony catalyst is highly corrosive so that this method is not practically useful due to the absence of a material suitable for a reactor. It is not known to commercially prepare 1,1,1,4,4,4-hexafluoro-2,3-dichlorobutane and 1,1,1,2,2,4,4,4-octafluorobutane. EP-A-0 425 887 discloses a method for replacing non-fluorine halogen atoms in organic compounds and catalysts used in the disclosed method. The exchange reaction is carried out in the gas phase in the presence of a chromium-free catalyst selected from the group of bismuth/earth alkaline catalysts and lanthanoid catalysts. The former ones may additionaly contain promoters in addition to the bismuth compounds. The described method can, among other reactions, be used for the conversion of hexachloro-1,3-butadiene with HF, wherein it is said to be preferable to carry out the process in the presence of elementary chlorine in order to increase the amount of open chain reaction products. The amount of open chain reaction products is described to be increased with increasing amounts of elementary chlorine. Therefore, the advantage of a chlorine-free process is not achieved by this method. DE-B-1 278 429 describes a method for the production of fluor halogenated alkanes or alkenes by reacting a mixture of hexachloro-1,3-butadiene with chlorine and HF in the presence of a Cr(III)oxyfluoride catalyst. The products obtained by the disclosed method are hydrogen free perhalogenated butanes or butenes. US-A-5,146,019 discloses a method for the production of 1,1,1,2,4,4,4-heptafluoro-2-butene and 2-chloro-1,1,1,4,4,4-hexafluoro-2-butene by reacting hexachlorobutadiene with hydrogen fluoride in the presence of a titanium halide or an antimony tri- or pentahalide as the catalyst. The disadvantage of this method is that it represents a liquid phase reaction which has to be carried out under increased pressure if reaction temperatures above room temperature are desired. Therefore, this method requires pressure-proof equipment and cannot be performed as a continuous process. SUMMARY OF THE INVENTION An object of the present invention is to provide a commercially useful method for preparing 1,1,1,4,4,4-hexafluoro-2,3-dichlorobutane, 1,1,1,4,4,4-hexafluoro-2-chloro-2-butene, 1,1,1,2,4,4,4-heptafluoro-2-butene and 1,1,1,2,2,4,4,4-octafluorobutane, which has not been found yet. We intensively studied to obtain a commercially useful method for preparing 1,1,1,4,4,4-hexafluoro-2,3-dichlorobutane, 1,1,1,4,4,4-hexafluoro-2-chloro-2-butene, 1,1,1,2,4,4,4-heptafluoro-2-butene and 1,1,1,2,2,4,4,4-octafluorobutane, found that these halogenated compounds can be prepared by selecting a suitable catalyst in the gas phase fluorination of easily available 1,1,2,3,4,4-hexachloro-1,3-butadiene, and then completed the present invention. Namely, the present invention provides a method for preparing at least one halogenated compound selected from the group consisting of 1,1,1,4,4,4-hexafluoro-2,3-dichlorobutane, 1,1,1,4,4,4-hexafluoro-2-chloro-2-butene, 1,1,1,2,4,4,4-heptafluoro-2-butene and 1,1,1,2,2,4,4,4-octafluorobutane, which comprises reacting 1,1,2,3,4,4-hexachloro-1,3-butadiene with hydrogen fluoride in the gas phase whereto no chlorine is added in the presence of a fluorinating catalyst, which is a fluoride and/or an oxyfluoride of at least one metal, selected from the group consisting of aluminum, chromium, manganese, nickel and cobalt. DETAILED EXPLANATION OF THE INVENTION The raw material 1,1,2,3,4,4-hexachloro-1,3-butadiene can be economically prepared by chlorinating butane. The catalyst may be a metal fluoride or a metal oxyfluoride. The metal fluoride and the metal oxyfluoride can be prepared, for example, by adding an alkali to a solution of a metal salt to precipitate a metal oxide and then fluorinating the metal oxide with HF. Specific examples of the metal salt are a chloride, a nitrate salt, a sulfate salt and the like. Specific examples of the alkali are ammonia, urea, an alkaline metal hydroxide and the like. Specific examples of the metal are one metal or a mixture selected from the group consisting of aluminum, chromium, manganese, nickel and cobalt. The metal fluoride and the metal oxyfluoride can be used with or without being supported on a suitable carrier. Specific examples of a suitable carrier are active carbon, aluminum fluoride and the like. The reaction is usually conducted in a continuous mode. The reaction temperature is usually from 250 to 450°C, preferably from 300 to 400°C. When the reaction temperature is low, it is disadvantageous-that the reaction slowly proceeds. The contacting time with the catalyst is usually from 1 second to 10 minutes, preferably from 5 to 50 seconds, more preferably from 10 to 30 seconds. The reaction pressure is not limited, but it is usually from 0.1 to 20 atm, preferably from 1 to 10 atm. The amount of HF can be selected from a range between 10 and 100 mol per one mol of hexachlorobutadiene, depending on the desired conversion, the ratio of the products, the contacting time and the reaction temperature. The reaction can be conducted in an amount larger than 100 mol of HF, but this is not practical because of low productivity. The reaction product can be fluorinated again by separating a lowly fluorinated material from necessary components and returning the lowly fluorinated material to the reactor, so that the yield of the desired material can be increased. The reaction converts the raw material to 1,1,1,4,4,4-hexafluoro-2,3-dichlorobutane, 1,1,1,4,4,4-hexafluoro-2-chloro-2-butene, 1,1,1,2,4,4,4-heptafluoro-2-butene and then 1,1,1,2,2,4,4,4-octafluorobutane successively. Accordingly, the conversion is controlled by suitably selecting the reaction temperature, the contacting time and the amount of HF and the lowly fluorinated material is recycled so that the necessary components can be obtained in a good yield. PREFERRED EMBODIMENTS OF THE INVENTION The present invention is illustrated by following Examples. Example 1 Pellets of oxides of the metals shown in Table 1 which had a diameter of 3 mm and a height of 3 mm were used. This catalyst (55 cc) was filled in a reactor tube (diameter: 20 mm) and then fluorinated with HF. The reaction temperature was adjusted to a temperature shown in Table 1, and then HF (flow rate: 500 cc/min) and 1,1,2,3,4,4-hexachloro-1,3-butadiene (flow rate: 10 cc/min) in gas states were supplied. The product was washed with water and then analyzed by GLC. The results are shown in Table 1. In the table, R-336 stands for 1,1,1,4,4,4-hexafluoro-2,3-dichlorobutane, R-1326 stands for 1,1,1,4,4,4-hexafluoro-2-chloro-2-butene, R-1327 stands for 1,1,1,2,4,4,4-heptafluoro-2-butene and R-338 stands for 1,1,1,2,2,4,4,4-octafluorobutane. GLC analysis condition: 3 m of PORAPACK-Q Temperature: increased from 100°C at a rate of 10°C/min Metal Reaction temperature Products R-336 R-1326 R-1327 R-338 Cr 300°C 56% 25% 14% 5% Cr 350°C 46% 34% 18% 2% Cr 400°C 43% 37% 19% 1% Al 400°C 25% 12% 11% 2% Mn 400°C 24% 10% 8% 3% Co 400°C 26% 14% 10% 2% Ni 400°C 18% 9% 8% 2%

Claims: A method for preparing at least one halogenated compound selected from the group consisting of 1,1,1,4,4,4-hexafluoro-2,3-dichlorobutane, 1,1,1,4,4,4-hexafluoro-2-chloro-2-butene, 1,1,1,2,4,4,4-heptafluoro-2-butene and 1,1,1,2,2,4,4,4-octafluorobutane, which comprises reacting 1,1,2,3,4,4-hexachloro-1,3-butadiene with hydrogen fluoride in a gas phase, whereto no chlorine is added in the presence of a fluorinating catalyst, which is a fluoride and/or an oxyfluoride of at least one metal, selected from the group consisting of aluminum, chromium, manganese, nickel and cobalt. A method according to claim 1, wherein the catalyst is prepared by fluorinating chromium oxide with hydrogen fluoride.

Inventors: AOYAMA HIROKAZU, KOYAMA SATOSHI, NAKADA TATSUO, AOYAMA, HIROKAZU, KOYAMA, SATOSHI, NAKADA, TATSUO
Applicants: DAIKIN IND LTD, DAIKIN INDUSTRIES, LTD.
Application year: 1993
Main classification: C07C17
IPC codes: C07C17, B01J27, C07C21, C07B61, C07C19