Estimating the π-bond energies and the stabilities of oxy-substituted carbocations

Hydroxy-substituted methyl cations CHn(OH)3-n+, n = 1-3 have been studied with the B3LYP/6-31G∗ and G3B3 levels of theory. Their relative stabilities have been estimated with isodesmic and isogyric reactions. Increased degree of substitution increases the stability of the cation, but, due to competition among the OH groups, this does not occur in a linear fashion. The π-bond energies are estimated as approximately 78, 55 and 43 kcal/mol per OH group for 1, 2 and 3, respectively.