Suzuki reaction over palladium-complex loaded MCM-41 catalysts

Palladium-complex loaded Al-MCM-41 catalysts have been used to heterogenize the homogeneous catalyzed Suzuki reaction. The Suzuki reaction is a convenient method for the C-C coupling of arylhalogenides with arylboronacids yielding biphenyles, The mesoporous catalyst supports were prepared by anchoring of alkylsilylsulfonic acid to as-prepared calcined Al-MCM-41. The PdCl2[Ph2P(CH2)(2)S(CH2)(3)SO3Na](2) complex was used as catalytically active precursor and directly loaded onto the support from solution. Materials were characterized by Si-29 MAS NMR, C-13 CPI MAS NMR, nitrogen adsorption, TG/DTA, CHNS analysis, XPS, and TEM. The Si/Al ratio of the Al-MCM-41 was 10.7. The pore size was approximate to 30 Angstrom. The catalytic tests were performed in a batch reactor at 78 degreesC in a toluene/ethanol/water mixture with sodium carbonate as base and cetyltrimethylammoniumbromide as surfactant. Conversions and selectivities were determined by gas chromatography. For comparison also large pore SEA type mesoporous molecular sieves were included. The results indicate that Pd-complex/MCM-41 catalysts can be successfully used in the Suzuki C-C-coupling reaction. Catalysts can be recycled and re-used. The recycled catalysts show an enhanced activity. (C) 2001 Elsevier Science B.V. All rights reserved.