Novel approach of thionyl chloride detection and disposal using a benzimidazole-based derivative: perspectives and proposals

Benzimidazoles are important heterocyclic compounds that exhibit a wide range of pharmacological and biological properties. Among all, sensitivity to Lewis acids provide a possibility to act as a fluorescent detectors for senzing the cathions, radicals, highly reactive low-molecular species with hazardous effects to environment and human health. Herein, we present the design and synthesis of N-((1H-benzo[d]imidazol-2-yl)methyl)cinnamamide (I) for the detection of readily reactive thionyl chloride (SOCl₂). Treatment of SOCl₂ with a novel benzimidazole-based compound I is accompanied by immediate color change. Although the process is irreversible the change noticeable by eye is profitable for a simple and rapid protection against the SOCl₂ exposure at amounts harmful for surroundings and body. In the context of environmental issue, the chemical reaction between the detector I and thionyl chloride is beneficial for the safe waste disposal. Thionyl chloride is recaptured in the structure of I throughout the reaction leading to a formation of stable compound II. Incorporation of residual traces of SOCl₂ into the structure of organic-type detector I represents effective route to achieve non-reactive and non-damaging derivatives. Accordingly, the organic non-liquid waste is subsequently stored and disposed in a safe manner.