Classical versus redox tautomerism: substituent effects on the keto/enol and sulfoxide/sulfenic acid equilibria

MP2/6-311+G** ab initio calculations have been carried out for a classical example of tautomerism, the keto/enol [RCOCH3/RC(OH)CH2] and an example of redox tautomerism, the sulfoxide/sulfenic acid [RS(O)H/RSOH]. Eleven R substituents have been examined. Both equilibria show proportional energies and similar dependence on the Swain–Lupton Fand Rparameters.