Cellulose Sulfuric Acid: Novel and Efficient Biodegradable and Recyclable Acid Catalyst for the Solid-State Synthesis of Thiadiazolo Benzimidazoles

Abstract

An efficient method for the synthesis of 2-substituted benzimidazoles has been developed. In this method, benzo[c][1,2,5]thiadiazole-4,5-diamine was condensed with different aldehydes in the presence of cellulose sulfuric acid under solvent-free conditions by simple physical grinding of reactants using a mortar and pestle at room temperature. The methodology is mild, high-yielding, and green, and the catalyst could be easily recycled.

Keywords:

• Benzimidazoles
• benzo[c][1,2,5]thiadiazole-4,5-diamine
• cellulose sulfuric acid
• different aldehydes

ACKNOWLEDGMENT

Financial assistance from the Council of Scientific and Industrial Research (Grant No. 01(2061)/06/EMR-II), New Delhi, is acknowledged.

Notes

Notes. Reaction conditions: Mixture of cellulose sulfuric acid (0.1 g), aldehyde (3.6 mmol), and benzo[c][1,2,5]thiadiazole-4,5-diamine (3.0 mmol) was ground at room temperature.

^a Yields refer to the pure isolated recovered catalyst.

^a Yields refer to isolated pure products and were characterized by NMR, IR, and mass spectral data.

Notes. Reaction conditions: Mixture of cellulose sulfuric acid (0.1 g), aldehyde (3.6 mmol), and benzo[c][1,2,5]thiadiazole-4,5-diamine (3.0 mmol) was ground at room temperature.

^a Yields refer to the pure isolated recovered catalyst.