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

Abstract

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. o-Nitroaniline is converted into the final desired product in 6 h at 180 °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.

Development of a Green Process for the Synthesis of Cyclopentanone Using Selective Aqueous Phase Hydrogenation of Furfural over Ni–Cu@MOF-5 Catalyst

“…The C�O link in carbonyl compounds has been reported to be activated by surface Cu + species. 19,75,82 Hence, probably in our case, Cu + has been shown to prevent the production of THFA by inhibiting the hydrogenation of the furan ring in the FFA molecule. As high temperatures reduces the activity of nickel to hydrogenate, CPO rather than CPL is the primary hydrogenation product.…”

“…In the tetrahedral coordinated Zn 4 O cluster, the band at 500.24 cm –1 , Zn–O stretching vibrations are attributed to this area. , The –C–O band at 1579 in 5 wt % Ni–Cu (1:1) @ MOF-5 indicates that the dicarboxylic acid interacted with Ni and Cu . The development of a Ni–Cu bimetal complex with a carboxylic group is indicated by the peaks at 636 and 476.32 cm –1 . , The FTIR spectra of both fresh and used catalysts revealed negligible structural changes. It shows that the surface of the catalyst that was previously used has no externally adsorbed species.…”

Preparation of carboxyl group functionalized FDU-15 type materials for the cyclization of CO2 with 2-aminophenol

“…9, was proposed based on the results and previous literature reports. [29][30][31][32] First, the polarization of CQO bonds of CO 2 and N-H bonds of 2-aminophenol occurred to form intermediate 1, induced by hydrogen bonding of COOH-MPs. Then, the reduction of CQO by DMAB afforded the formation of intermediate 2.…”

A Triazine Based Porous Organic Polymer as an Efficient Hydrogen‐Bond Donor and Acceptor Cooperative Heterogeneous Catalyst for the Synthesis of 2‐Substituted Benzimidazoles

“…Also, the selectivity control towards the intramolecular nucleophilic attack to form 2-substituted benzimidazoles avoiding the formation of bisimine, in the presence of catalyst as evident from the GC profile analysis (Figure S3) could also be due to the hydrogen bond mediated activation of this step. [32] 2 CuMVs 1.30 Hour/303 K Water 90-96 [31] 3 CuO-np/SiO 2 4-14 Hour/RT MeOH 68-93 [33] 4 Na 2 S 2 O 5 adsorbed on silica gel 8-12 Hour/RT EtOH 72-93 [34] 5 10 % (1 : 1) CuÀ Ni/MCF 6 Hour/180 °C DMF: Water 100 [35] 6 Zn/BN 4 Hour/140 °C Acetonitrile 88-97 [36] 7 Nano-ZnS 1 Hour/7 °C EtOH 85-98 [37] Thus the reaction proceeds via imine formation followed by the reaction of second NH 2 group in the o-phenylenediamine leading to the formation of dihydrobenzimidazole which undergoes aromatization under air oxidation resulting in the desired product. [32] Computational Study on the Proposed Mechanism…”