Substituent Chemical Shifts of 2-Aryl Derivatives of Benzimidazole, Benzimidazolium Ion, and Benzimidazoline

摘要

NMR spectra of a series of 2-arylbenzimidazoles, 2-aryl-1,3-dimethylbenzimidazolium iodides, and 2-aryl- 1,3-dimethylbenzimidazolines were examined by correlating ¹H and ¹³C chemical shift values with the Hammett substituent constants ヲ. The signals corresponding to C-2 of the imidazole ring show good correlation with the largest ヱ values in each series. The ヱ values for C-2 of the benzimidazoles and the benzimidazolium ions were very close, but that of the benzimidazoline was about a half of the former series.