Process for the dimerization of hexafluoropropene oxide
AssigneeHoechst Aktiengesellschaft
InventorGerhard Kuhne
Life of this patent
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Abstract
In the dimerization of hexafluoropropene oxide to give oligomeric acid fluorides of the formula ##STR1## the ratio of the oligomeric constituents formed is directed, in an improved manner, towards the formation of the dimer (n=0) if the reaction is carried out in the presence of a catalyst system which consists of a mixture of a copper (I) compound and a copper (II) compound mixed with a complex-forming agent from the group of the nitriles, isocyanides, tertiary phosphines and cyclic hydrocarbons with 6 to 12 ring atoms and 2 to 3 double bonds in the ring, and an aprotic organic solvent. The dimer is an intermediate product in the synthesis of perfluoropropyl perfluorovinyl ether, the latter being employed as a comonomer in fluorine-containing copolymers.
Claims1
A process for the catalytic dimerization of hexafluoropropene oxide, optionally mixed with hexafluoropropene, in the presence of an aprotic organic solvent at temperatures of -10.degree. to +10.degree. C. and under autogenous pressure, wherein the catalyst employed is a composition containing
- (a) a mixture of a copper(I) compound of the formula Cu.sub.m X and a copper(II) compound of the formula Cu.sub.m/2 X, wherein X=0 or an anion and m denotes the valency of X, in the weight ratio of 70:30 to 95:5 and
- (b) a complex-forming agent from the group of the nitriles of the formula ##STR6## wherein R.sup.1 and R.sup.2, which are identical or different, denote H, CN or an alkyl radical of 1 to 6 C atoms and one of these alkyl radicals R.sup.1 or R.sup.2 can optionally be substituted by a CN group, and wherein R.sup.1 and R.sup.2 can also be linked to form a cyclic alkylene group with 3 to 10 C atoms, and wherein furthermore n denotes an integer from 0 to 5,
- the isocyanides of the formula R.sup.3 NC, wherein R.sup.3 denotes an alkyl radical, a cycloalkyl radical, an aralkyl radical or a mononuclear or binuclear aryl radical which is optionally substituted by 1 to 3 CH.sub.3 groups,
- the tertiary phosphines of the formula R.sup.4 R.sup.5 R.sup.6 P, wherein R.sup.4, R.sup.5 and R.sup.6, which may be identical or different, denote an alkyl radical, a cycloalkyl radical, an aralkyl radical or a mononuclear or binuclear aryl radical which is optionally substituted by 1 to 3 CH.sub.3 groups,
- or the cyclic hydrocarbons with 2 or 3 double bonds and with 6 to 12 C atoms in the ring, or in bicyclic or tricyclic ring systems,
- or mixtures of these complex-forming agents, the molar ratio of component (a) to component (b) being 1:1 to 1:8.
Dependencies are inferred from the claim text.