Catalytic Synthesis of Benzimidazoles and Organic Carbamates by Polymer Supported Zinc Catalyst through CO2 Fixation
Utilization of carbon dioxide in chemical fixations for synthesis of fine chemicals like benzimidazoles, organic carbamates etc. is very demanding in recent era as carbon dioxide is cost effective, sustainable, and green renewable C1 sourse. In this article we represent the design and synthesis of organically modified polystyrene bounded heterogeneous [PS-Zn(II)-SALTETA] catalyst. The catalyst has been characterized thoroughly by Fourier Transformed Infrared spectroscopy, Atomic Absorption Spectroscopy, thermo gravimetric analysis, PXRD, SEM and EDAX studies. The catalyst was used for cyclization of o-phenylenediamines through insertion of carbon dioxide in order to produce benzimidazoles in presence of dimethylamine borane (DMAB). The developed catalytic procedure is sustainable, economical and efficient owing to utilization of ethanol/water as a biodegradable and environment friendly solvent system. Besides benzimidazoles production the catalyst was also very active for manufacture of organic carbamates from anilines and n-butyl bromide under atmospheric CO2 pressure in solvent free condition at room temperature and the catalytic protocol shows outstanding functional group tolerance. Moreover the catalyst is highly recyclable and reusable.