Charge density analysis of some processes involving intramolecular hydrogen transfer

The mechanisms of: (a) keto-enol tautomerism, (b) pinacol rearrangement, and (c) methanediol decomposition were studied by means of AIM and Hirshfeld atomic partitionings. The three processes follow concerted mechanisms, but a hydrogen-bridged structure is never formed along the reaction path of the pinacol rearrangement.