GB952281A - Preparation of vinyl fluorinated ethers - Google Patents

Abstract

Aliphatic fluorinated vinyl mono and di ethers are made by reacting an aliphatic fluorinated mono or di-carboxylic acid fluoride including carbonyl fluoride preferably perfluorinated, with hexafluoropropylene epoxide, in the presence of as catalyst of activated carbon or a fluoride of an alkali metal, silver or a quaternary ammonium, and then pyrolysing the resulting product, which is stated to be a 2-propoxypropionyl fluoride. A highly polar inert solvent e.g. a poly alkyl glycol ether, ethylene glycol dimethyl ether or a hydrocarbon nitrile may advantageously be employed in the first stage. In a modified process the initial 2-propoxypropionyl fluoride is first converted to a monovalent metal salt and then pyrolysed. The pyrolysis may be achieved at 200-600 DEG C. or over alkali metal, especially potassium sulphate pellets, at 170-250 DEG C. Carbonyl fluoride, perfluoropropionyl fluoride, perfluoroacetyl fluoride, oxalyl fluoride and perfluoroglutonyl fluoride are specified starting materials. The invention also includes a perfluorinated divinyl ether of the general formula: <FORM:0952281/C2/1> when n=2 to 20 and specifically perfluoroethylene bis (perfluorovinyl ether) and perfluoropentamethylene bis (perfluorovinyl ether). Examples are given. The products are stated to be capable of being homo or copolymerized with ethylenic monomers e.g. tetrafluorothylene (see Division C3).ALSO:Fluorinated vinyl ethers (see Division C2) and especially di thers of the general formula: CF2=CF-O-(CnF2n)-O-CF=CF2 where n = 2 to 20 may be homo or copolymerized with other ethylenic monomers e.g. tetrafluoroethylene as in Specification 781,532 to give cross-linked perfluorocarbon resins. The particular description relates to the synthesis of perfluoro ethylene bis (perfluorovinyl ether) and perfluoro pentamethylene bis (perfluorovinyl ether).