Synthesis and Characterization of Benzimidazole‐Based Scaffolds

ABSTRACT The present research includes the preparation of 2‐mercaptobenzimidazole (S1) by the reaction of orthophenylenediamine with carbon disulfide in alcoholic potassium hydroxide. Subsequently, S1 was reacted with aqueous hydrazine to yield 2‐hydrazinebenzimidazole (S2) . 2‐hydrazinebenzimidazole ( S1) was reacted with anhydrous phthalic acid to yield phthalazine derivative (S3) . Compounds S4 and S5 were prepared by the reaction of orthophenylenediamine with benzoic acid and its derivative in the presence of hydrochloric acid (4N). Compound S6 was obtained by the reaction of orthophenylenediamine with p ‐nitrobenzaldehyde in the presence of a mixture of hydrogen peroxide and concentrated hydrochloric acid. Mannich bases (compound S7 ) were prepared by the condensation of 2‐mercaptobenzimidazole and formaldehyde with diphenylamine. The carboxylic acid derivative S8 was prepared by reacting 2‐mercapto‐5‐methoxybenzoimidazole with chloroacetic acid in the presence of potassium hydroxide and ethanol as a solvent, and was raised for 5 h. The prepared compounds were characterized using physical and spectroscopic methods such as FTIR and 1 H‐NMR, in addition to using classification tests to identify a portion of the active groups in these compounds.