Magnetic Ru nanocatalysts for green solvent-free oxidation reactions of aromatic alcohols

A kind of magnetic hybrid organic-inorganic nanoparticles containing Ru metal (Fe3O4@SiO2-FPBA-Ru) was prepared. It was spherical with the characteristic lattice fringe of ruthenium atom. The size was in the range of 5-15 nm and it contained 0.30 mmol/g Ru. Its saturation magnetization value was 15.95 emu/g, which could be easily and efficiently recovered from solution through an external magnet. It was also stable below 240 degrees C and hot filtration experiment proved Ru wasn't leaked from Fe3O4@SiO2-FPBA-Ru in 70 degrees C oxidation reaction. It could be recovered and reused at least 7 cycles. The low amount of Fe3O4@SiO2-FPBA-Ru (75 mmol%) could convert the 99 % of 1-phenylethanol to acetophenone under solvent-free system, which verified its green and environment-friendly properties. The yield was exceed that of homogeneous (RuCl3, 85 %). Beside this, the TON (5181), TOF (7430 h(-1)) in oxidation of 1-phenylethanol and high conversion yields for a series of oxidation reactions of aromatic secondary alcohols proved the high catalytic ability of Fe3O4@SiO2-FPBA-Ru. These laid a foundation for its industrial applications.