In 2, 3-dihydro-2-(2-hydroxyphenyl)-l, 3-dimethyl-l~-benzimidazole (3), the acidic hydrogen of a phenolic oxygen-hydrogen bond is near a carbon-hydrogen bond activated as a donor of hydride by two adjacent lone pairs in a dihydro aromatic ring. This juxtaposition does not promote the formation of molecular hydrogen. Instead, thermolysis of compound 3 appears to lead to tautomerization of the hydroxyphenyl group and heterolysis of the carbon- ...
![2-(1,3-dimethyl-1H-benzo[d]imidazol-3-ium-2-yl)phenolate Structure](https://image.chemsrc.com/caspic/157/113036-44-5.png)