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

Silica-coated maghemite nanoparticles (γ-Fe 2 O 3 ) decorated with octamolybdate-containing thiaminium (protonated vitamin B1) produced a four-component nanocatalyst (γ-Fe 2 O 3 @SiO 2 /VB1/α-Mo 8 O 26 = 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.