Synthesis and characterization of SiO2-supported ruthenium complexes containing aromatic sulfonamides: as catalysts for transfer hydrogenation of acetophenone

Abstract

3-Amino-N-aryl-benzenesulfonamides (1-3) were successfully synthesized by the reaction of m-phenylenediamine and various benzenesulfonyl chlorides. Then, a series of ruthenium complexes (4-6) were prepared from the reaction of [RuCl2(p-cymene)](2) and 1-3. Finally, SiO2-supported Ru(II) complexes (7-9) were prepared by an impregnation method. The synthesized compounds and materials were characterized by different methods such as NMR, FT-IR, TG/DTA, nitrogen adsorption-desorption (BET), SEM and EDX. Also, the solid state structures of 4-6 were determined by single-crystal X-ray diffraction. 4-9 were used as catalysts for the transfer hydrogenation of acetophenone. 4-9 showed good catalytic activity and so the effects of the different groups were also examined. For the transfer hydrogenation of acetophenone, 7-9 had similar activity to 4-6. However, the longer lifetime of 7-9 makes them more advantageous than the non-supported catalysts (4-6) in terms of catalytic cycle. Therefore, the effect of SiO2 was investigated as a catalyst and the results show that excess silicon(IV) oxide was a surprisingly active catalyst for the hydrogenation of acetophenone under these conditions.