Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Reexamination Certificate
2002-05-29
2003-02-18
Siegel, Alan (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
Reexamination Certificate
active
06521802
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a process for preparing a fluorine-containing hydrocarbon compound such as hydrofluorocarbons (HFC).
2. Description of the Related Art
Fluorine-containing hydrocarbon compounds such as hydrofluorocarbons (HFC) are used as substitute compounds of chlorofluorocarbons (CFC) and hydrochlorofluorocarbons (HCFC) which having a strong action of depleting an ozone layer, and are important compounds used as blowing agents, coolants, cleaners or propellant which do not deplete ozone in the current industry.
It has already been known to use an antimony compound as a catalyst in the process for preparing a hydrofluorocarbon. For example, Japanese Patent Kokai Publication No. 169829/1991 discloses a process for preparing CF
3
CHCl
2
, CF
3
CHCIF or CF
3
CHF
2
by fluorinating CClF
2
CHCl
2
without directly using hydrogen fluoride. Japanese Patent Kokoku Publication No. 91202/1995 discloses a process for preparing CF
3
CHCl
2
by fluorinating CClF
2
CHCl
2
or CCl
2
FCHCl
2
, and WO96/01797 discloses a process for preparing 1,1,1,3,3-pentafluoropropane by fluorinating 1,1,1,3,3-pentachloropropane with hydrogen fluoride in the presence of an antimony halide compound.
Although it is known that the antimony halide compound is a highly corrosive compound, none of the patent publications mentioned above refers to corrosion of a reaction apparatus or prevention of such corrosion of a reaction apparatus. According to the description of examples of these publications, the concentration of the antimony halide compound used as a catalyst is usually within a range from about 0.1 to 10 mol based on 100 mol of hydrogen fluoride, and is within a range from about 20 to 30 mol at most. However, the inventors of the present invention confirmed that, when using the antimony halide compound having a concentration within such a range as the catalyst, it exhibits a metallic corrosion action in a very high level.
As described in Japanese Patent Kokai Publication No. 169829/1991, when the fluorination is conducted only by using a fluorine atom-containing antimony halide compound in the absence of hydrogen fluoride in the system, an operation of refluorinating the consumed antimony halide compound and an apparatus therefor are required. Therefore, the process can not be said to be economically advantageous.
WO98/33754 discloses a process for fluorinating 1,1,1,3,3,3-hexachloropropane in a solvent of 1-chloro-1,1,3,3,3-pentachloropropane or 1,1,1,3,3,3-hexafluoropropane and Japanese Patent Kokai Publication No. 217704/1996 discloses a process for simultaneously fluorinating dichloromethane and 1,1,1-trichloroethane, respectively, and these publications describe that the objective compound can be obtained in a good yield and that the corrosion prevention effect of the reaction apparatus is also achieved.
However, as described in WO98/33754, the process using the product or the intermediate product as the solvent is not deemed to be economically advantageous because the volume of a reaction vessel should be increased corresponding to the increase of the amount of the solvent to be used. Furthermore, since some compound has poor compatibility with hydrogen fluoride, phase separation between the hydrogen fluoride and the solvent is likely to occur in the reaction vessel, thereby to drastically lower the reaction efficiency. Therefore, such a process is applicable to limited cases.
The process of simultaneously fluorinating dichloromethane and 1,1,1-trichloroethane described in Japanese Patent Kokai Publication No. 217704/1996 is economically disadvantageous because when any one product is required, the other product which is not necessary is prepared.
In WO98/33754 and Japanese Patent Kokai Publication No. 217704/1996, although the amount of the antimony halide compound based on hydrogen fluoride is not specifically prescribed, the amount is several mol % at most as described in examples of the former publication and there is not an example wherein the antimony halide compound is used in a high concentration. On the other hand, the latter publication describes that, since the temperature of the reaction vessel is maintained at a temperature higher than a boiling point of hydrogen fluoride under a reaction pressure, hydrogen fluoride does not exist in a liquid state in the reaction vessel. That is, this description shows that the concentration of the antimony halide compound is nearly 100 mol % based on hydrogen fluoride. The absence of hydrogen fluoride in the reaction solution is not suited to efficiently conduct the reaction because the feed of a fluorine source in the fluorination reaction is delayed.
As the corrosion-proof fluorination process, Japanese Patent Kokai Publication No. 233102/1995 discloses a process using a reaction vessel made of a fluororesin and Japanese Patent Kokoku Publication No. 88591/1995 discloses a process for lowering the corrosiveness by maintaining a water content in a raw material at a low level, respectively. However, it is not possible to provide an equipment comprising a resin-lined instrument with a heating equipment in the process using the reaction vessel made of the fluororesin described in Japanese Patent Kokai Publication No. 233102/1995 as described in the specification thereof, so that it is difficult to control the reaction temperature. In addition, the raw material is fed in a gaseous form and, therefore, a pre-heater of the raw material is required, resulting in high equipment cost. The process for maintaining the water content in the raw material at a low level described in Japanese Patent Kokoku Publication No. 88591/1995 is not deemed to be economical because dehydration of an organic material requires addition of a dehydrating agent and distillation and also dehydration of hydrogen fluoride requires electrolysis and addition of a fluorine gas, resulting in increase of the number of the steps.
It has hitherto been known that a hydrogen fluoride solution of SbCl
p
F
5−p
has very high corrosiveness and the reactivity of the hydrogen fluoride solution of SbCl
p
F
5−p
with respect to the reaction of fluorinating the organic material increases with the increase in concentration thereof. The commonly used concentration was within a range from 1 to 10 mol %, as disclosed in examples of WO96/01797, in view of the economical efficiency.
However, the present inventors found that, when using SbCl
p
F
5−p
in a concentration, which is comparatively higher than that has hitherto been used, the corrosiveness of SbCl
p
F
5−p
is lowered within a conventionally used concentration range by the same degree as in the case of a comparatively low concentration range, or a concentration lower than a lower limit in the conventionally used range. Consequently, the present invention has been completed.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a process for preparing a fluorine-containing halogenated hydrocarbon compound (HFC), which is important as a substitute or an alternative compound of CFC or HCFC, economically advantageously with good selectivity while suppressing a corrosive action of a reaction vessel.
The inventors have intensively studied to achieve the object described above and devised the present invention which provides a process capable of suppressing the corrosion of a reaction vessel made of a metal while maintaining a high fluorinating ability of an antimony halide compound by using a mixture of hydrogen fluoride and an antimony halide compound, which mixture contains the antimony halide compound in a comparatively high concentration. The above mixture of the antimony halide compound and hydrogen fluoride may also be expressed that it exists in the form of a hydrogen fluoride solution containing an antimony halide compound in a high concentration at normal temperature under normal pressure.
In an aspect, the process for preparing a fluorine-containing halogenated hydrocarbon compound of the present invention is characteri
Nakada Tatsuo
Shibanuma Takashi
Shibata Noriaki
Takubo Seiji
Birch & Stewart Kolasch & Birch, LLP
Daikin Industries Ltd.
Siegel Alan
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