Process for the preparation of fluorinated olefin

Details Process for the preparation of fluorinated olefin Process for the preparation of fluorinated olefin

1998-11-13

2001-04-03

Siegel, Alan (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Halogen containing

Reexamination Certificate

active

06211420

ABSTRACT:

TECHNICAL FIELD
This invention relates to a process for preparing a fluorinated olefin having a carbon—carbon double bond, the carbon atoms of which have a fluorine atom.
BACKGROUND ART
Fluorinated olefins having a carbon—carbon double bond, the carbon atoms of which have a fluorine atom, are used as intermediate materials for fluorinated paraffins used as chlorofluorocarbon alternatives, and monomers for fluorinated polymers, and are produced in a large scale.
Heretofore, these fluorinated olefins have been produced by reacting an olefin compound having a carbon—carbon double bond, the carbon atoms of which have a chlorine atom, with an alkali metal fluoride. For example, 1,2,3,3,4,4,5,5-octafluorocyclopentene is produced by reacting 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene with potassium fluoride [U.S. Pat. No. 3,024,290, ibid. U.S. Pat. No. 3,567,788, and J. Org. Chem., 28, 112(1963)]. However, the yield of the intended product is insufficient for the production thereof in a commercial scale, and thus, enhancement of the yield is desired.
DISCLOSURE OF INVENTION
In view of the foregoing, the object of the invention is to provide an improved process for preparing a fluorinated olefin having a carbon—carbon double bond, the carbon atoms of which have a fluorine atom, by reacting a halogenated olefin having at least one carbon—carbon double bond, a carbon atom or the carbon atoms of which have a chlorine atom, and having the carbon atom or atoms with a single bond having no halogen atom other than a fluorine atom in the molecule, with an alkali metal fluoride, whereby the target fluorinated olefin is produced in an enhanced yield.
Thus, in accordance with the present invention, there is provided a process for preparing a fluorinated olefin having a carbon—carbon double bond, the carbon atoms of which have a fluorine atom, by reacting a halogenated olefin having at least one carbon—carbon double bond, a carbon atom or the carbon atoms of which bond have a chlorine atom or atoms bound thereto, and, in which the carbon atom or atoms with a single bond in the molecule have no halogen atom other than a fluorine atom, with an alkali metal fluoride, characterized in that said reaction of the halogenated olefin with the alkali metal fluoride is conducted in the presence of an organic halogen-containing compound having a carbon—carbon single bond, a carbon or the carbons of which have at least one halogen atom other than fluorine atom.
BEST MODE FOR CARRYING OUT THE INVENTION
Halogenated Olefin
A halogenated olefin used as a stating material in the present invention is that which has at least one carbon—carbon double bond in the molecule, a carbon atom or the carbon atoms of which bond have a chlorine atom or atoms bound thereto, and, in which the carbon atom or atoms with a single bond in the molecule have no halogen atom other than fluorine atom. The halogenated olefin preferably has a fluorine atom or atoms, and the fluorine atom or atoms may be bound to any of the carbon atoms. The number of carbon atoms in the halogenated olefin is not particularly limited, but is usually in the range of from 2 to 30, preferably from 3 to 20 and more preferably from 4 to 10.
As preferable examples of the halogenated olefin, there can be mentioned those which are represented by the following general formula (1):
R
1
ClC=CClR
2
  (1)
wherein R
1
and R
2
independently represent an alkyl group, a fluoroalkyl group or a fluorine atom, or R
1
and R
2
may be bonded together to form an alkylene group or a fluoroalkylene group.
When R
1
and R
2
in the formula (1) are fluoroalkyl groups or bonded together to form a fluoroalkylene group, the reaction takes place rather rapidly and therefore these groups are preferable. The number of carbon atoms in the alkyl, fluoroalkyl, alkylene and fluoroalkylene groups are not particularly limited, but is usually in the range of from 1 to 20, preferably from 2 to 10 and more preferably from 2 to 8.
As specific examples of the alkyl group, there can be mentioned methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-amyl, isoamyl, t-amyl, n-hexyl and n-octyl groups.
As specific examples of the fluoroalkyl group, there can be mentioned fluoromethyl, difluoromethyl, trifluoromethyl, 1,2,2-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, 1,1,1,2,2-pentafluoroethyl, 1,2,2,3,3-pentafluoropropyl, 1,1,2,2,3,3-hexafluoropropyl and 1,1,1,2,2,3,3-heptafluoropropyl groups. Of these, perfluoroalkyl groups such as trifluoromethyl, 1,1,1,2,2-pentafluoroethyl and 1,1,1,2,2,3,3-heptafluoropropyl groups are preferable.
As specific examples of the alkylene group, there can be mentioned propylene, isopropylene, butylene, amylene and hexylene groups are preferable. Of these, propylene, butylene and amylene groups are preferable. A propylene group is most preferable.
As specific examples of the fluoroalkylene group, there can be mentioned 1,1,2,2-tetrafluoropropylene, 1,1,2,2,3-pentafluoropropylene, 1,1,2,2,3,3-hexafluoropropylene, 1,1,2,2,3,3-hexafluorobutylene, 1,1,2,2,3,3,4-heptafluorobutylene and 1,1,2,2,3,3,4,4-octafluorobutylene. Of these, perfluoroalkylene groups such as 1,1,2,2,3,3-hexafluoropropylene and 1,1,2,2,3,3,4,4-octafluorobutylene are preferable. 1,1,2,2,3,3-Hexafluoropropylene is most preferable.
As specific examples of the halogenated olefin, there can be mentioned straight chain halogenated olefin compounds such as 2,3-dichloro-1,1,1,4-tetrafluoro-2-butene, 2,3-dichloro-1,1,1,4,4-pentafluoro-2-butene, 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene, 1,2-dichloro-1,3,3,4-tetrafluoro-1-butene, 1,2-dichloro-1,3,3,4,4-pentafluoro-1-butene, 1,2-dichloro-1,3,3,4,4,4-hexafluoro-1-butene, 1,2-dichloro-1,3,3,4,4,5-hexafluoro-1-pentene, 1,2-dichloro-1,3,3,4,4,5,5-heptafluoro-1-pentene, 1,2-dichloro-1,3,3,4,4,5,5,5-octafluoro-1-pentene, 2,3-dichloro-1,1,1,4,4,5-hexafluoro-2-pentene, 2,3-dichloro-1,1,1,4,4,5,5-heptafluoro-2-pentene and 2,3-dichloro-1,1,1,4,4,5,5,5-octafluoro-2-pentene; and alicyclic halogenated olefin compounds such as 1,2-dichloro-3,3,4,4-tetrafluorocyclopentene, 1,2-dichloro-3,3,4,4,5-pentafluorocyclopentene, 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene, 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclohexene, 1,2-dichloro-3,3,4,4,5,5,6-heptafluorocyclohexene and 1,2-dichloro-3,3,4,4,5,5,6,6-octafluorocyclohexene.
These halogenated olefins may be used either alone or as a combination of at least two thereof.
Organic Halogen-Containing Compound
The organic halogen-containing compound used in the present invention is not particularly limited, provided that it has a carbon—carbon single bond, a carbon or the carbons of which have at least one halogen atom other than fluorine atom. However, in view of the separation and purification of the intended fluorinated olefin, an organic halogen-containing compound capable of reacting with an alkali metal fluoride to give the intended halogenated olefin is preferable. Such organic halogen-containing compound preferably includes those which are represented by the following general formula (2):
R
3
X
1
C=CX
2
R
4
  (2)
wherein X
1
and X
2
represent a halogen atom, and R
3
and R
4
independently represent an alkyl group, a haloalkyl group or a halogen atom, or R
3
and R
4
are bonded together to form an alkylene group or a haloalkylene group, and either R
3
or R
4
has a halogen atom other than fluorine atom.
X
1
and X
2
in the formula (2) represent a halogen atom which specifically includes fluorine, chlorine, bromine and iodine atoms. Of these, fluorine and chlorine atoms are preferable. A chlorine atom is most preferable.
R
3
and R
4
in the formula (2) independently represent an alkyl group, a haloalkyl group or a halogen atom, or R
3
and R
4
are bonded together to form an alkylene group or a haloalkylene group, and either R
3
or R
4
has a halogen atom other than fluorine atom. Of these, haloalkyl and haloalkylene groups are preferable. The number of carbon atoms in the alkyl, haloalkyl, alkylene and haloalkylene groups is not particularly limited, but is

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