A catalytic synthesis of polyfl uoroolefi ns was developed proceeding from polyfl uorochlorocarbons with the use of industrially produced nickel-chromium catalyst. Three ways of the catalytic synthesis of fl uoroolefi ns were implemented: the cleavage of vicinal chlorine atoms from polyfl uorochlorocarbons, the replacement of vinyl chlorine atoms by hydrogen in fl uorochloroolrfi ns, and the reductive dimerization of polyfl uorochlorocarbons containing a trichloromethyl group. The condition of a prolonged operation of the nickel-chromium catalyst was found consisting in the application of quartz for absorption of the hydrogen fl uoride formed as a side product.Fluoroolefi ns are the most important raw materials for preparation versatile widely used polyfl uorinated compounds. The currently known procedures of the synthesis of fl uoroolefi ns based on chemical transformations of polyfl uorochlorocarbons in the medium of organic solvents are not attractive for processing due to the necessity of wastes utilization [1][2][3]. This disadvantage is absent from the described catalytic processes for fl uoroolefi ns synthesis in the gas phase. The dechlorination of polyfl uorochlorocarbons was studied in the presence of various catalysts: copper, cobalt [4], lead [5]. The application of this process is hampered by the high temperature (400-600°C) close to the pyrolysis that adversely affects the yield and the purity of the target compounds. Another considerable disadvantage is the fast deactivation of the catalyst. It was shown [6] that the catalyst based on nickel and chromium operated for 5 h at 350-450°C. The described in a patent [7] catalytic replacement of chlorine by hydrogen in fl uoroolefi ns and the reductive dimerization of polyfl uorochlorocarbons were performed under the catalysis of platinum group metals, e.g., ruthenium.The goal of this study was the development of a catalytic synthesis of polyfl uoroolefi ns proceeding from polyfl uorochlorocarbons. To this end we studied the industrially produced nickel-chromium catalyst applied to the fi ne purifi cation of hydrogen from oxygen and traces of CO and CO 2 in the processes of hydrogenation of benzene, phenol, aniline, dehydrolysate, and also in the process of isotope exchange. We developed three ways of the catalytic synthesis of fl uoroolefi ns: the elimination of vicinal chlorine atoms from the fl uorochlorocarbons, the substitution of vinyl chlorine atoms in fl uorochloroolefi ns by hydrogen, and the reductive dimerization of polyfl uorochlorocarbons containing a trichloromethyl group.Production of fl uoroolefi ns by eliminating vicinal chlorine atoms from fl uorochlorocarbons. Polyfl uorochlorocarbons of various structures containing vicinal chlorine atoms were converted into the corresponding olefi ns with the use of the nickel-chromium catalyst at the temperature from 150 to 270°C, essentially lower than used with the previously described catalysts (400-600°C). The 1,1-difl uorotetrachloroethane dechlorinated the most readily giving 1,1-difl uorodich...
Transfer Catalysis. -(PETROV*, V. A.; MARSHALL, W. J.; KRESPAN, C. G.; CHERSTKOV, V. F.; AVETISIAN, E. A.; J. Fluorine Chem. 125 (2004) 1, 99-105; DuPont Cent. Res. Dev., Exp. Stn., Wilmington, DE 19880, USA; Eng.) -M. Schroeter 18-082
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