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Paper | Regular issue | Vol 26, No. 6, 1987, pp.1581-1586
Published online, 1st January, 1970
DOI: 10.3987/R-1987-06-1581
Structure and Basicity of 2-Guanidiobenzimidazoles

Carmen Acerete, Javier Catalán, Fernando Fabero, Marta Sánchez-Cabezudo, Rosa María Claramunt, and José Elguero

*Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid, Spain


A theoretical and experimental study of the basicity of three 2-guanidinobenzimidazoles has been carried out. The most abundant tautomer, the structure of the protonated molecule, and the reason of the relatively low pKa 1 are discussed. In addition, a careful 1H and 13C nmr study provides information about the influence of intramolecular hydrogen bonds on annular tautomeric rates.