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

Perfluoroalkyl iodide R f I [R f = (CF 2 ) n O(CF 2 ) 2 SO 2 F, n = 2, (a); n = 4, (b); (CF 2 ) 4 Cl, (c)] reacted with substituted benzene C 6 H 5 Y (Y = alkyl, OCH 3 , CF 3 , F, Cl, Br, I) in the presence of copper in acetic anhydride to give the corresponding mixture of isomeric disubstituted benzene (R f C 6 H 4 Y). 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.