Silica gel modified with tetraalkylammonium halides as an available and efficient catalyst for the synthesis of cyclic organic carbonates from epoxides and CO2
The development of a silica-promoted highly selective synthesis of 1,2 or 1,3-dithioethers via solvent-free one-pot tandem reactions of an allyl bromide with excess thiol at room temperature is described. The choice of silica gel, either pre-calcined or moistened with water, exhibited notable regioselectivity in the formation of dithioethers. Plausible mechanistic routes were explored and postulated.
A first and efficient procedure has been developed for microwave-assisted transfer hydrogenation of ketones. Silica gel-supported ligand 2 has been prepared for the transfer hydrogenation. This immobilized ligand-Ru complex acted as an efficient catalyst for the hydrogen transfer reaction of ketones. The MW-assisted reactions using the supported ligand 2 could reach completion within 20~40 min.
A supported dual acidic ionic liquid was prepared via anchoring 3-sulfobutyl-1-(3-propyltriethoxysilane) imidazolium hydrogen sulfate onto common silica gel by covalent bond. The novel immobilized acidic ionic liquid illustrated high catalytic activity in esterification and acetalization reactions. The products could be separated by simple decantation and the recovered catalyst could be recycled without remarkable loss of catalytic activity even after eight runs for esterification and six runs for acetalization.
Silica: An efficient catalyst for one-pot regioselective synthesis of dithioethers