The Influence of Substituent Groups on the Resonance Stabilization of Benzene. An ab Initio Computational Study

Publisher Website
Google Scholar
Abstract
Accurate G3(MP2) calculations of the enthalpies of formation (ΔfH298) of organic molecules permit replication and extension of calculations that were formerly dependent on experimental thermochemical results. A case in point is Kistiakowski's classical calculation of the total stabilization enthalpy of benzene relative to that of cyclohexene, called for many years the “resonance energy”. This paper investigates extension of the classical calculation to substituted benzenes. Slight modification of the usual procedure for ΔfH298 determination permits exclusion of all empirical information, leaving a purely ab initio result. Stabilization enthalpies relative to the corresponding 4-substituted cyclohexenes are presented for benzene, toluene, aniline, phenol, phenylacetylene, styrene, ethylbenzene, and phenylhydrazine. In the process of calculating these stabilization enthalpies, we have also obtained 42 values of ΔfH298 for monosubstituted benzenes, cyclohexenes, and cyclohexanes, 24 of which are not in the standard reference literature. For the remaining 18 G3(MP2) results, the unsigned mean difference between calculated ΔfH298 values and experimental results is ±0.91 kcal mol-1.

This publication has 22 references indexed in Scilit: