Energetic characteristics of the substituents in para- and meta-substituted derivatives of benzoic acids

Highlights: • First attempt to describe substituent effects in terms of total energies. • Key quantity is the difference of total energies of para and meta conformers. • Total energy proved to be a useful quantity in studying substituent effects. This article is the first attempt to describe substituent effects in terms of total energies of the substituted derivatives of benzoic acid. The key quantity in this attempt is the difference of the total energies of the para and meta conformers. This quantity is then correlated with Hammett substituent constants and with some theoretical parameters of the electronic structure of the substituent. While it was previously unclear that the total energy of a molecule would prove to be a useful quantity in studying substituent effects, our research shows that, indeed, this energetical difference correlates well with other parameters if only they also relate to both of these conformers, that is they are differences of their individual counterparts determined for both of these conformers separately.