GB675804A - Improvements in or relating to a hydrocarbon drying oil - Google Patents

Abstract

A hydrocarbon drying-oil is prepared by copolymerizing a mixture of a mono-iso-olefin having not more than eight carbon atoms per molecule, preferably isobutylene, and a conjugated polyolefin having not more than eight carbon atoms per molecule, preferably butadiene-1,3, equal to from 60 to 95 per cent of the combined weight of the mono- and polyolefins, in the presence of a catalyst comprising substantially anhydrous hydrogen fluoride at a temperature of from - 80 DEG to - 40 DEG C., and separating the drying-oil from the resultant reaction mixture. Other mono-iso-olefins which may be used are 2-methylbutene-1, 3-methylbutene-1, 2-ethylbutene-1, 2,3-dimethylbutene-1, 3-methylhexene-1 and 2-methylbutene-2, and other suitable polyolefins are piperylene, isoprene, hexadiene-1,3, 2-methyl-pentadiene-1,3, 4-methylpentadiene-1,3, 2,3-dimethylbutadiene-1,3, 3-methylhexadiene-1,3, hexadiene-2,4 and heptadiene-2,4. Instead of the iso-olefins, tertiary alkyl fluorides may be employed, which, in a hydrogen-fluoride containing system, may be considered iso-olefin donors. The temperature is preferably controlled by conducting the reaction in the presence of an internal refrigerant such as propane, butane, methyl chloride, methyl bromide, ethyl chloride, ethyl bromide, perfluorobutane and solid carbon dioxide. The catalyst is introduced gradually into the reaction mixture, preferably in gaseous form in small quantities as the reaction proceeds. Methods of recovery of the catalyst and of the copolymer product are described. The copolymers may be further polymerized with alkenyl halides, allyl esters, vinyl esters, vinyl aromatics, acrylates and maleic acid derivatives.