Studies on fluoroalkylation and fluoroalkoxylation: 2. Perfluoroalkylation of aromatics with perfluoroalkyl iodides in the presence of copper

Abstract

Perfluoroalkyl iodide RfI [Rf = (CF2)nO(CF2)2SO2F, n = 2, (a); n = 4, (b); (CF2)4Cl, (c)] reacted with substituted benzene C6H5Y (Y = alkyl, OCH3, CF3, F, Cl, Br, I) in the presence of copper in acetic anhydride to give the corresponding mixture of isomeric disubstituted benzene (RfC6H4Y). The conversion and yield depend on both the amount of copper used and nature of substituent. The likely explanation is that the reaction may involve a free radical process. The perfluoroalkyl radical can be trapped by cyclohexene, isopropylbenzene and styrene. Using DMSO in place of acetic anhydride as a solvent the reaction takes a different course, it is believed that the reaction in DMSO proceeds through a perfluoroalkylcopper intermediate.