We present a theoretical study of the CH3CXNH ⇌ CH2CXNH2 tautomerism. The analysis is performed in terms of global descriptors of reactivity, such as electronic chemical potential, chemical hardness and chemical softness. Chemical hardness is used to study the relative stability in the frame of the maximum hardness principle. Chemical softness appears to be related to the molecular polarizability, and it is used to discuss relative stability in the context of the minimum polarizability principle. Both empirical rules are simultaneously satisfied for this equilibrium. Transition states, in which the transferred proton is found about midway between the donor and acceptor atoms, are rationalized in terms of the Brönsted coefficient for the relative position along the reaction coordinate and the Marcus equation for the energy barriers. Substituent effects on the activation properties are analyzed in a partitioned form that probes the effect of the substituent group on the molecular properties at the ground-state and transition-state structures.
Áreas temáticas de ASJC Scopus
- Química física y teórica