Hydrogenation and dehalogenation of aryl chlorides and fluorides by the sol–gel entrapped RhCl3–Aliquat 336 ion pair catalyst

摘要: Abstract The SiO 2 sol–gel entrapped ion pair [(C 8 H 17 ) 3 NMe] + [RhCl 4 . n O] − , generated from RCl 3H O, Aliquat 336® and Si(OMe) catalyzes at 80°C 16 atm. the hydrogenation of aryl fluorides chlorides to give halogen-free hydroaromatics. Fluorobenzenes initially yield fluorocyclohexanes which eliminate HF, in a non-catalytic process, followed by cyclohexenes. In contrast, chlorobenzenes are first dehalogenated corresponding benzene derivatives, that second step hydrogenated cyclohexanes. Aryl bromides undergo dehalogenation as well, but only presence free radical scavenger. catalyst these reactions is leach-proof recyclable with little or no loss activity.