Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Reexamination Certificate
2000-03-07
2001-03-27
Siegel, Alan (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
Reexamination Certificate
active
06207869
ABSTRACT:
FIELD OF THE INVENTION
This is a division of application Ser. No. 08/738,117 filed Oct. 25, 1996, which in turn is a continuation of Ser. No. 08/166,432 filed Dec. 14, 1993. The instant invention relates to producing perhalofluorobutanes and perhalofluorohexanes, more particularly it relates to their production by utilizing tetrafluoroethylene (hereinafter referred to as “TFE”) and chlorotrifluoroethylene (hereinafter referred to as “CTFE”) with selected perhalofluoroethanes containing 2 to 4 nonfluorine halogen substiutuents, and 2 to 4 fluorine substituents in the presence of a polyvalent metal halide such as an aluminum chloride or chlorofluoride as catalyst.
The perhalofluoroalkanes can be used as intermediates for the manufacture of hydrofluorobutanes which in turn in view of their inherently low ozone depletion potentials, are environmentally attractive alternatives for perchlorofluorocarbons (CFC's) in such established uses as refrigerants, expansion agents for making foams, aerosols, heat transfer media, propellants, solvents, cleaning and drying agents, gaseous dielectrics, power cycle working fluids, polymerization media, carrier fluids, fire extinguishants, among other applications.
BACKGROUND OF THE INVENTION
Joyce, U.S. Pat. No. 2,462,402 (Feb. 22, 1949) discloses a process for the production of highly halogenated fluoroalkanes which comprises contacting TFE with a polyhalogenated alkane, preferably a methane, containing at least one chlorine atom and no more than two fluorine atoms, in the presence of a polyvalent metal halide catalyst, preferably aluminum chloride.
Sievert, et. al., in U.S. Pat. No. 5,157,171 (Oct. 20, 1992) disclose a process for preparing chlorofluorinated propanes, CHCl2F5, by contacting monofluorodichloromethane (CHCl2F) with TFE in the presence of a modified aluminum chloride catalyst containing fluoride as well as chloride ligands.
The disclosure of the previously identified references is hereby incorporated by reference.
SUMMARY OF THE INVENTION
One aspect of the invention relates to a process for producing valuable perhalofluorobutanes from commercially available perhalofluoroethanes and polyfluoroethylenes such as tetrafluoroethylene (TFE) and chlorotrifluoroethylene (CTFE).
The inventive process relates to producing perhalofluorobutanes, where “halo” represents non-fluoro halogens, in particular Cl and/or Br, by reacting TFE and/or CTFE with one or more selected perhalofluoroethanes.
Broadly, the invention comprises:
(i) contacting
(a) CYF=CF
2
, where Y is Cl or F, with
(b) a perhalofluoroethane selected from the group comprising CX
2
FCX
2
F or CX
2
FCXF
2
or CF
3
CX
2
F or CBrF
2
CF
2X
where X can be either Cl or Br, in the presence of
(c) a catalytically effective polyvalent metal halide, preferably aluminum chloride or aluminum chlorofluoride, at a temperature and pressure and for a time effective to produce
(d) a reaction product mixture containing at least one perhalofluorobutane selected from the group comprising C
4
YX
4
F
5
, C
4
YX
3
F
6
, C
4
BrYXF
7
, and C
4
YX
2
F
7
where Y and X are as defined above; and
(ii) recovering at least one of said perhalofluorobutanes from the reaction mixture.
The inventive process is capable of producing perhalofluorobutanes having the formula C4X2-5F5-8, X=Br or Cl, derived from perhalofluoroethanes as defined above by reaction with TFE that may be represented by the following equations (1)-(3):
CF2=CF2+C2X4F2, e.g. C2Cl4F2→C4X4F6, e.g., C4Cl4F6, (1)
CF2=CF2+C2X3F3, e.g. C2Cl3F3→C4X3F7, e.g., C4Cl3F7, (2)
CF2=CF2+C2X2F4, e.g. C2Br2F4→C4X2F8, e.g., C4Br2F8, (3)
wherein usually the fluorine content of each of the products C4X4F6, C4X3F7, and C4X2F8 is the sum of the fluorine contents of the low and perhalofluoroethane reactants.
Similarly, the inventive process is capable of producing perhalofluorobutanes having the formula C4X2-5F5-8, X=Br or Cl, derived from perhalofluoroethanes as defined above by reaction with CTFE that may be represented by the following equations (4)-(6):
CClF=CF2+C2X4F2→C4X5F5, (4)
CClF=CF2+C2X3F3→C4X4F6 (5)
CClF=CF2+C2X2F4→C4X3F7 (6)
wherein usually the fluorine content of each of the products C4X5F5, C4X4F6, and C4X3F7 is the sum of the fluorine contents of the CTFE and perhalofluoroethane reactants.
The reaction product mixture may contain products having fluorine content greater than the sum of the fluorine content of the starting materials. For example, the reaction of CCl2FCClF2 with TFE may yield in addition to C4Cl3F7, a C4Cl2F8 product, e.g., CF3CCl2CF2CF3. In some cases, a halogen exchange reaction may occur between the primary C4Cl3F7 product and the metal halide catalyst which contains fluorine ligands, either originally present or formed therein during the course of the reaction with a chlorofluoroethane reactant.
The reaction product mixture may also contain products having fewer fluorine groups than the sum of the fluorine groups in the starting materials. All such products with fluorine content greater or smaller than the sum of the fluorine content of the starting materials are also valuable products as they are also reducible to hydrogen containing products using known techniques, e.g., converting at least one carbon-nonfluorine halogen bond to a carbon-hydrogen bond.
When using starting materials corresponding to CX2FCX2F, where X can be Cl and/or Br, the reaction product mixture may additionally contain products derived from reaction of at least two moles of fluoroolefin with one of the perhalofluoroethane. For example, C6Cl4F10 (C2F5CCl2CCl2C2F5) and C5CCl5F9 (CClF2CF2CCl2CCl2C2F5), may both originate from TFE and CCl2FCCl2F in the presence of an aluminum chloride or chlorofluoride catalyst. Without wishing to be bound by any theory or explanation, it is believed that the nonafluoride, e.g., CSCl5F9, may result from a halogen exchange reaction of the intermediate C4Cl4F6, or first formed product C6Cl4F10, with the aluminum chloride catalyst. The halogen exchange reaction can be shown by the following equation (7);
2CF2=CF2+C2X4F2, e.g. C2Cl4F2→C6X4F10, e.g., C6Cl4F10, (7)
DETAILED DESCRIPTION
In accordance with the present invention perhaloftuorobutanes, as defined above and generally as the major reaction products, can be prepared by reacting TFE or CTFE with selected perhalofluoroethanes in the presence of an effective metal halide such as aluminum chloride or chlorofluoride, as catalyst.
Such reactions illustrated by equations (1)-(6) above, indicate a stoichiometry of 1 mole of the fluoroolefin per mole of the perhalofluoroethane reactant. The reaction illustrated by equation (7) indicates a stoichimetry of 2 moles of fluoroolefin per mole of reactant. Generally, however, the mole ratio of starting materials or reactants may vary from about 0.3 to about 3.0 moles of the fluoroolefin per mole of the halofluoroethane reactant with about 1:1 being used typically for making perhalofluorobutanes, whereas 2:1 being used typically for making perhalofluorohexanes.
The catalyst is typically an anhydrous aluminum chloride or chlorofluoride wherein the fluorine content ranges from about 3 to 64% by weight, and is such that the composition corresponds to that of AlCl3-rFr wherein r is typically about 1 to about 2.8 (hereinafter referred to as a “modified aluminum chloride catalyst”). Such modified aluminum chloride catalytic compositions may be prepared by reacting anhydrous AlCl3 with an excess of at least one of chlorofluorocarbon, hydrochlorofluorocarbon, or hydrofluorocarbon as disclosed in Sievert, et. al. U.S. Pat. No. 5,157,171, the disclosure of which is incorporated herein by reference. It is, however, desirable to avoid formation of AlF3 because such a composition is not believed to be an active catalyst for the instant invention.
The quantity of modified aluminum chloride used in the present process may vary widely, b
Nappa Mario Joseph
Sievert Allen Capron
E. I. Du Pont de Nemours and Company
Shipley James E.
Siegel Alan
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