Palladium nanocolloids supported on chitosan behave as very efficient heterogeneous catalysts in the Heck reaction of aryl bromides and activated aryl chlorides in tetrabutyl-ammonium bromide as solvent and tetrabutylammonium acetate as base. Only 15 min is required to convert bromobenzene or p-nitrochlorobenzene into cinnamates. The efficiency of this catalyst is due to the stabilization of Pd colloids by the solvent and to a very fast PdH neutralization by the base. In contrast, no reaction occurs when utilizing imidazolium-based ionic liquids. The stability of the catalyst allows an extensive recycle in the coupling of iodoaromatics with butyl acrylate.
Heck reaction catalyzed by nanosized palladium on chitosan in ionic liquids
NACCI, Angelo;MONOPOLI A.;SABBATINI, Luigia;CIOFFI, NICOLA;DITARANTO, NICOLETTA
2004-01-01
Abstract
Palladium nanocolloids supported on chitosan behave as very efficient heterogeneous catalysts in the Heck reaction of aryl bromides and activated aryl chlorides in tetrabutyl-ammonium bromide as solvent and tetrabutylammonium acetate as base. Only 15 min is required to convert bromobenzene or p-nitrochlorobenzene into cinnamates. The efficiency of this catalyst is due to the stabilization of Pd colloids by the solvent and to a very fast PdH neutralization by the base. In contrast, no reaction occurs when utilizing imidazolium-based ionic liquids. The stability of the catalyst allows an extensive recycle in the coupling of iodoaromatics with butyl acrylate.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
