Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Patent
1993-07-20
1994-11-15
Sigel, Alan
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
570176, C07C 1908
Patent
active
053649915
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for preparing 1,1,1,4,4,4-hexafluorobutane.
RELATED ART
1,1,1,4,4,4-Hexafluorobutane is s compound useful as a refrigerant carrier, a foaming agent and a solvent. As a method for preparing 1,1,1,4,4,4-hexafluorobutane, a method is known which comprises hydrogenating 2-chloro-1,1,1,4,4,4-hexafluorobutene-2 or 1,1,1,4,4,4-hexafluorobutene-2 in a liquid phase in the presence of various noble metal catalyst. However, such method is not commercially suitable, since a by-product is produced in a large amount so that the yield is low.
A method which comprises hydrogenating 1,1,1,4,4,4-hexafluorobutyne-2 in the presence of a palladium catalyst is also known (Youji Huaxue, 2, 125 (1985)). However, this method requires a raw material which cannot be easily produced and is not commercially preferable method.
PROBLEM TO BE SOLVED BY THE INVENTION
An object of the present invention is to provide a method for preparing 1,1,1,4,4,4,-hexafluorobutane in a gas phase by a hydrogen reduction without the above problems.
MEANS FOR SOLVING THE PROBLEM
The inventors have intensively studied to develop an easy method for commercially preparing 1,1,1,4,4,4-hexafluorobutane in a high yield, and found that 1,1,1,4,4,4-hexafluorobutane can be obtained with good selectivity and a high yield when 2-chloro-1,1,1,4,4,4-hexafluorobutene-2 is used as a raw material and is hydrogenated in a gas phase in the presence of an alloy catalyst containing platinum or palladium, thus completed the present invention.
The gist of the present invention resides in a method for preparing 1,1,1,4,4,4-hexafluorobutane comprising reducing 2-chloro-1,1,1,4,4,4-hexafluorobutene-2 with hydrogen in the presence of a hydrogenation catalyst comprising an alloy which comprises at lease one first metal component selected from the group consisting of platinum and palladium and at lease one second metal component selected from the group consisting of silver, copper, gold, tellurium, zinc, chromium, molybdenum and thallium.
In the present invention, the hydrogenation catalyst contains the alloy comprising the first metal component and the second metal component, which alloy is an active component of the catalyst.
It is generally known that, in the alloy catalyst, a property of the component element is exhibited according to an alloy composition. In the present invention, an amount of the second metal component is suitably from 0.01 to 500 parts by weight, particularly from 0.1 to 300 parts by weight per 100 parts by weight of the first metal component in view of the utilization of the property of platinum and palladium.
A suitable carrier of the hydrogenation catalyst is, for example, active carbon, alumina, zirconia and titania. While a content of the alloy supported on the carrier in the catalyst may be from 0.05 to 5% by weight, a preferable content is from 0.5 to 2% by weight. The particle size of the carrier gives no strong effect on the reaction, and it is preferably from 0.01 to 100 mm.
A ratio of 2-chloro-1,1,1,4,4,4-hexafluorobutene-2 (R-1326) to hydrogen in the hydrogenation reaction can be widely varied. However, at least a stoichiometric amount of hydrogen (namely, at lease 2 mol of hydrogen per 1 mol of R-1326) is usually used so that the hydrogenation reaction is conducted and a chlorine atom is eliminated. The amount of hydrogen may be relatively larger than the stoichiometric amount, for example at least 4 mol per 1 mol of R-1326.
A reaction mode is a gas phase reaction in which a gaseous R-1326 and hydrogen are passed in contact with the hydrogenation catalyst filled in a reactor tube. A gas phase reaction may be a fixed bed gas phase reaction, a fluidized bed gas phase reaction or the like.
The reaction pressure is not limited and may be any of an increased pressure, a decreased pressure and an atmospheric pressure. The reaction is preferably conducted under increased pressure or atomospheric pressure, since the reduced pressure requires a complex apparatus.
The reaction tempe
REFERENCES:
patent: 5146019 (1992-09-01), Bielefeldt et al.
patent: 5210340 (1993-05-01), Bielefeldt et al.
"Chemical Abstracts" vol. 101, 1984 54508u.
Aoyama Hirokazu
Koyama Satoshi
Nakada Tatsuo
Seki Eiji
Daikin Industries Ltd.
Sigel Alan
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