GB772110A - Unsaturated polyfluorinated organic compounds - Google Patents

Abstract

The invention comprises carboxylic acids of the formula RFCH=CHCOOH where RF is a polyhalogenohydrocarbon group having at least two fluorine atoms on the carbon atom nearest the olefinic bond. RF may be perfluoroalkyl, preferably C1-C20 perfluoroalkyl, perfluorocycloalkyl, preferably having not more than six carbon atoms in the ring, or perfluoro - aromatic, preferably a perfluorophenyl group. The acids may be prepared by hydrolysing a nitrile of formula RFCH = CHCN (described in Specification 772,109) in the presence of a base. The acids may also be prepared by adding a compound of formula RFI to acrylonitrile to obtain a compound of formula RFCH2CHICN, which is then dehydroiodinated and hydrolysed, e.g. with alcoholic potassium hydroxide, to obtain the acid. Metal salts of the acids, such as sodium salts, may be decarboxylated, e.g. by heating with ethylene glycol and boric acid, in a solvent from which hydrogen can be abstracted, such as water or a solvent having a C-H, O-H or N-H bond, to obtain olefins of formula RFCH = CH2. The silver salts of the acids may be simultaneously decarboxylated and iodinated to obtain compounds of formula RFCH = CHI. In examples: (1) g ,g ,g -trifluoroacrylonitrile is hydrolysed to form g ,g ,g -trifluorocrotonic acid; (2) acrylonitrile is reacted with trifluoroiodomethane to obtain g ,g ,g -trifluoro-a -iodobutyronitrile, which is dehydroiodinated and hydrolysed to obtain g ,g ,g -trifluorocrotonic acid; (3) the sodium salt of trifluorocrotonic acid is decarboxylated to obtain 3,3,3-trifluoropropene; (4) the silver salt of trifluorocrotonic acid is iodinated and decarboxylated to obtain 3,3,3-trifluoro-1-iodopropene.