Magnetic Thiaminum Octamolybdate Nanocatalyst for Oxygenation of Styrenes to Benzaldehydes and Tandem Synthesis of Benzimidazoles

Silica-coated maghemite nanoparticles (gamma-Fe2O3) decorated with octamolybdate-containing thiaminium (protonated vitamin B1) produced a four-component nanocatalyst (gamma-Fe2O3@SiO2/VB1/alpha-Mo8O26 = SMNPB1Mo). The as-prepared material with particle sizes ranging from 10 to 50 nm and a specific surface area of 57 m(2)/g showed high activity with a TOF of 312 h(-1) and excellent selectivity for the conversion of styrenes to benzaldehydes using tert-butyl hydroperoxide as an oxidant followed by a one-pot synthesis of benzimidazoles under solvent-free conditions. A radical pathway was suggested based on scavenging experiments. The catalyst proved to be easily recoverable using a ferromagnet and usable for at least five runs while retaining its activity and structural integrity.