A facile method for catalyst immobilisation on silica: Nickel-catalysed Kumada reactions in mini-continuous flow and batch reactors

An unsymmetrical salen-type nickel(II) complex was readily immobilised onto functionalised silica using a convenient tethering method. The supported complex was an effective recyclable heterogeneous catalyst in a room temperature cross-coupling reaction between 4-bromoanisole and phenylmagnesium chloride. Leaching of the metal into solution from the supported catalyst proved almost negligible. The silica-supported catalyst was ideal for use in a mini-continuous flow reactor since it did not exhibit swelling which is common and a problem for organic polymer resin supports.