Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Patent
1998-08-19
1999-12-14
Siegel, Alan
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
562851, C07C 2118, C07C 5158
Patent
active
060020555
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention pertains to a process for making dihalodifluoromethanes and their homologues by reacting fluorinated epoxides and dihalogen compounds in the presence of selected metal and metal-containing promoters at elevated reaction temperatures.
TECHNICAL BACKGROUND
Dihaloperfluoroalkanes, which may be represented by X(CF.sub.2).sub.n Y, where n is 1 to 7, are useful for making functional fluoromonomers and other useful organofluoromaterials. The diiodoperfluoroalkanes are also useful as chain transfer reagents for fluoroelastomers and in the free radical polymerization of fluorinated vinyl monomers. See for example U.S. Pat. Nos. 4,243,770 and 4,361,678, which are incorporated herein by reference.
CF.sub.2 I.sub.2 is a useful starting material for making organofluoromaterials and as a chain transfer agent for fluoroelastomers, but preparation methods have been shown to have low yields. The reaction of hexafluorocyclopropylene oxide (HFPO) with iodine in a stainless steel vessel has been reported (see John, E. O., et al., Inorg. Chem. 1992, 31, pp. 329-331) but the yield was reported to be 15-30%. Reaction of difluorocarbene with iodine gives less than a 20% yield of CF.sub.2 I.sub.2 as reported by Mitsh, R. A. J., Heterocyl. Chem. 1964, I, p. 233, and others.
SU-A- 1 297 411 teaches a preparation of difluorodibromomethane by reaction of bromine with hexafluoropropylene oxide, without catalyst.
SUMMARY OF THE INVENTION
This invention pertains to a process for making .alpha.,.omega.-dihaloperfluoromethanes and their homologues, comprising: or metal-containing promoter according to Equation I, wherein said promoter is selected from the group consisting of Ni, CuI, Ni/Cu, and Ni/Zn: ##STR1## wherein RF represents a perfluoroalkyl or a perfluoroalkyl with one or more ether oxygen, chlorine, bromine, iodine, hydrogen, sulfonyl fluoride, nitrile, ester, acyl chloride or acyl fluoride substituent; of I, Br, and Cl; weight percent or greater.
DETAILS OF THE INVENTION
This invention is an improvement to a process for making dihalodifluoromethanes, generally represented as CF.sub.2 XY, and their higher homologues, generally represented as X(CF.sub.2).sub.n Y (X,Y=I, Br, Cl; n=2, 3 or 4), and fluorinated acyl fluorides from fluorinated epoxides and dihalogens. The general process may be shown by Equation (I) as follows: ##STR2##
When this reaction takes place in the presence of the catalyst, a yield of about 70 weight percent or greater, preferably about 80 weight percent or greater, of the desired CF.sub.2 XY is often obtained. In the absence of catalyst, the yield is often closer to about 30 weight percent or less of the desired product. R.sub.F in Equation I represents a perfluoroalkyl or a perfluoroalkyl with one or more ether oxygen, chlorine, bromine, iodine, hydrogen, sulfonyl fluoride, nitrile, ester, acyl chloride or acyl fluoride substituents, and serves to define the fluorinated epoxides useful in this invention.
The improvement in the aforementioned process is the presence of a selected metal or metal-containing promoter. As used herein, a "metal or metal-containing promoter" is comprised of a zero-valent metal (e.g., Ni, Cu) or combination of metals (i.e., Ni/Cu, Ni/Zn) or a metal halide (e.g., CuI), usually in the form of a powder or slurry. Alternatively the "metal or metal containing promoter" may be a metal or combination of metals, which form a process vessel (e.g., tube, tank, autoclave, reactor), so that the vessel's surface promotes the reaction. Examples of preferred vessel materials include nickel alloy materials such as Hastelloy.RTM. C (Union Carbide, Danbury, Conn.). As found in the Metals Handbook, American Society for Metals, Metals Park, Ohio 44073, 1985, p. 20.28, Hastelloy.RTM. C is comprised of about 56% Ni. Therefore, as stated herein, the "presence of" a promoter means that the reactants are exposed to the metal or metal-containing promoter, either by mixing the reactants with a particulate or slurry form of the promoter, or by contact with a conta
REFERENCES:
patent: 4243770 (1981-01-01), Tatemoto et al.
patent: 4361678 (1982-11-01), Tatemoto et al.
Database WPI, Section Ch, Week 9411, Derwent Publications Ltd., 1993.
Z. Yang et al., Journal of the American Chemical Society, 117, No. 19, Apr. 17, 1995.
E. O. John et al., Inorg. Chem., 31, 329-331, 1992.
R. A. Mitsh, J. Heterocyl. Chem., 1, 233, 1964.
Z. Yang, J. Am. Chem. Soc., 118, 8140-8141, 1996.
E. I. Du Pont de Nemours and Company
Siegel Alan
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