Immobilization of a N-substituted azaphosphatrane in nanopores of SBA-15 silica for the production of cyclic carbonates†
Abstract
A novel N-substituted azaphosphatrane molecular precursor bearing an alkyne tether was synthesized using a multi-step strategy and covalently immobilized onto SBA-15 type silica through triazole linkages by means of the well-known click chemistry. The resulting hybrid material, [7]@SBA-15, was characterized well by methods appropriate to molecular species (e.g. solid state 13C, 31P and 29Si NMR, infrared spectroscopy and elemental analysis) as well as techniques more commonly associated with the characterization of mesoporous solids (nitrogen sorption isotherms, powder X-ray diffraction, TGA analysis). The catalytic activity of [7]@SBA-15 was then evaluated in the coupling of CO2 with two epoxides (styrene oxide and epichlorohydrin) and compared to its monotriazole modified AZAP molecular analog, 8. This work represents the first example of silica modified N-substituted azaphosphatrane for the production of cyclic carbonates.