Bimetallic Cu-Ni Nanometal Supported over Mesocellular Silica Foam As a Novel Catalyst for One-Pot Synthesis of Benzimidazole in DMF As a Bifunctional Reagent

Benzimidazole has several applications in different industries but is used mainly in the pharmaceutical sector. Due to its high demand, the production of benzimidazole by clean and green catalytic processes has become important. In the present study, we have optimized a method to achieve a one-pot synthesis of benzimidazole selectively over a meso-cellular foam (MCF) supported bimetallic catalyst, Cu-Ni@MCF. This catalyst provides active metal sites for hydrogenation of o-nitroaniline to o-phenylenediamine (OPDA) as well as cyclization of OPDA into the final product, benzimidazole. Along with the bifunctionality of the catalyst, the solvent consisting of a mixture of dimethylformamide (DMF) and water (2:1) plays a significant role in providing the in situ source of hydrogen and carbon dioxide for both the hydrogenation and cyclization steps, respectively. oNitroaniline is converted into the final desired product in 6 h at 180 degrees C and 800 rpm (for the lab reactor). Characterization of the synthesized catalyst was done to understand its activity and selectivity. The reaction mechanism and kinetics were established, and the apparent activation energy was calculated. Optimization studies were done to get the best results for the reaction. The non-noble-supported nanometal catalyst aids in cutting down the cost of the overall system and reduces the reaction period. It is a clean and green process.

Automated summary

In this study, we optimized a method for the one-pot synthesis of benzimidazole using a bimetallic catalyst supported by meso-cellular foam (MCF). The catalyst exhibited bifunctionality, allowing for the hydrogenation of o-nitroaniline to o-phenylenediamine (OPDA) and the cyclization of OPDA into benzimidazole. The use of a solvent mixture provided an in situ source of hydrogen and carbon dioxide, which played a significant role in the reaction. The synthesized catalyst was characterized and the reaction mechanism and kinetics were established.