Synthesis of novel benzimidazoles at room temperature, under solvent-free condition and their biological studies

An efficient and facile synthesis of substituted novel benzimidazoles (3a-3h) mediated by fruit juices viz.Cocos nuciferaL. juice,Citrus limettajuice andCitrus sinensisL. juice, via condensation of substituted aldehydes (1a-1h) ando-phenylenediammine (2a) under solvent-free condition at room temperature is presented in this paper. The purity of compounds was confirmed by melting point and thin layer chromatography. All synthesized compounds (3a-3h) were fully characterized via NMR and FTIR spectral data and evaluated for in vitro herbicidal activity againstRaphanus sativusL. (Radish) seeds. The compounds (3a-3h) were also evaluated for their antibacterial activity againstErwinia cartovoraandXanthomonas citriby inhibition zone method. Antifungal activity was also determined againstRhizoctonia solaniandColletotrichum gloeosporioidesby poisoned food techniques method. From activity data, it was found that compounds3dand3ewere most active againstR.sativusL. (root) andR.sativusL. (shoot), respectively. Compound3ghas shown maximum inhibition zone i.e. 8.00 mm againstE.cartovoraat 2000 mu g/mL concentration. MaximumX.citriigrowth was inhibited by compounds3ashowing inhibition zone 5.20 mm at highest concentration. Compound3fwas found most active againstR.solani and C.gloeosporioidesfungus at 2000 mu g/mL concentration. In comparison with the conventional methods, the present method complies with several key requirements of green chemistry principles such as the utilization of renewable feedstock, auxiliary aqueous conditions and reduces waste with the use of nature-derived catalyst. Therefore, the present method offers an attractive option because of its ecological safety, environmental acceptance, cost effective and easy workup process. [GRAPHICS] .