Novel nickel-immobilized-SiO-TiO fine particles in the presence of cetyltrimethylammonium bromide as a catalyst for ultrasound-assisted-Kumada cross-coupling reaction.

Kumada cross-coupling reaction is useful for producing biphenyls, where nickel and copper have been widely investigated as catalysts but mainly homogeneous ones. In this study, we investigated ultrasound-assisted-Kumada cross-coupling reaction over the heterogeneous catalysts in which Ni, Cu, or both was immobilized on aminopropylsilane-functionalized-SiO-TiO prepared in the presence of cetyltrimethylammonium bromide (CTAB). The presence of CTAB effectively prevented the particle growth and therefore SiO-TiO fine particles with high surface area (502 m g) were formed. The Ni-immobilized catalyst showed high catalytic activity for the ultrasound-assisted-Kumada cross-coupling reaction of a wide variety of substrates and was reusable three times. Performing the reaction under ultrasound irradiation was very effective in significantly accelerating the reaction rate compared with the conventional mechanical method. In contrast to Ni, Cu was deposited on the support as crystalline Cu(OH) and the resulting catalysts with Cu and Ni-Cu were less active and less stable under the reaction conditions.