The stability of aryl carbanions derived from pyridine N-oxide: the role of resonance in stabilizing aryl anions.

ABSTRACT: The gas phase stability of carbanions centered at various positions on pyridine N-oxide were investigated by computational and experimental methods. In addition, G3MP2 computations were completed on ring-deprotonated pyridine and N-methylpyridinium. With these species, the effect of a nitrogen-centered positive charge on carbanion stability was assessed. Introduction of the nitrogen-oxide group into the benzene ring decreases the DeltaH(acid) by approximately 20 kcal/mol, but surprisingly, the effect is nearly independent of the position of the group (ortho, meta, or para). The results indicate that the N-oxide offers a balance of field, resonance, and local effects that cancels out any positional preferences. G3MP2 calculations indicate that a similar lack of positional selectivity is see

SUBMITTER: Koehn SK 

PROVIDER: S-EPMC2802662 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature