Benzimidazole, 1-methyl-, Chichibabin

A rate study of benzimidazoles with weak electron-donating groups showed that the rate of the Chichibabin amination decreased as the strength of the electron-donating character increased (i.e., 1,5-dimethyl > 5-methoxy-l-methyl > 1,5,6-trimethylbenzimidazole) (77CHE903). Because the substrates do not contain sterically hindered substituents, the rate decrease is a function of the increased electron density in the system, particularly the decreased effective positive charge at the 2-position. 

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