Wydział Chemii

Iweta Pryjomska-Ray

Andrzej Gniewek

Anna M. Trzeciak

Józef J. Ziółkowski

Włodzimierz Tylus

2006

Topics in Catalysis

40

173-184

10.1007/s11244-006-0119-1

Naukowa

Angielski

Artykuł

Pd(II)/Al2O3and Pd(0)/Al2O3, containing 0.6% of palladium were characterized by EDX, SEM and XRD methods and used ascatalysts of the Heck coupling of bromobenzene with butyl acrylate at 140
C in molten [Bu4N]Br salt. Monoarylated (trans-PhCH = CHC(O)OBu) (1) and diarylated (Ph2C = CHC(O)OBu) (2) products were obtained in amounts dependent on kind ofbase present in the system (Scheme 1). During the reaction palladium was partially leached from the support forming [Bu4N][PdBr4]complex that catalyze Heck reaction or undergo readsorption on Al2O3. These soluble palladium complexes are partially reduced toPd soluble nanoparticles which can also be anchored on Al2O3giving active catalyst of Pd(0)/Al2O3type. Reduction of Pd(II) toPd(0) during catalytic process at the presence of bases (NaHCO2, NaHCO3, NaOAc, Cs2CO3) was studied by XPS method and thetotal reduction was observed in reactions of PdCl2(PhCN)2with NaHCO2or with NaHCO3and [Bu4N]Br. It was experimentallyproved that heterogenized catalyst, Pd(0)/Al2O3, after oxidative addition of aryl halides, serve as a source of soluble palladiumspecies and colloidal nanoparticles that are active as homogeneous catalysts.

Heck reaction, XPS, XRD, SEM, heterogenized catalysts, Pd colloid, Pd nanoparticles.

http://dx.doi.org/10.1007/s11244-006-0119-1

http://link.springer.com