A Green Route for the One-Pot Synthesis of 1,2-Disubstituted Benzimidazoles Using Iron(III) Phosphate under Solventless Conditions

1,2-Disubstituted benzimidazoles are selectively synthesized in high yields under extremely mild conditions via the condensation of o-phenylenediamine derivatives with aldehyde derivatives using catalytic amount of iron(III) phosphate under solvent-free conditions. The use of readily available iron(III) phosphate as a reusable and recyclable catalyst makes this process quite simple, convenient, and environment-friendly.