Related Experiment Video
Updated: Oct 3, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
The influence of substituent groups on the resonance stabilization of benzene. An ab initio computational study
1Chemistry Department, The Brooklyn Center, Long Island University, Brooklyn, New York 11201, USA. drogers@liu.edu
Abstract:
Accurate G3(MP2) calculations of the enthalpies of formation (Delta(f)H298) 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 Delta(f)H298 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 Delta(f)H298 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 Delta(f)H298 values and experimental results is +/-0.91 kcal x mol(-1).
Related Concept Videos
Electrophilic Aromatic Substitution: Sulfonation of Benzene
Directing Effect of Substituents: ortho–para-Directing Groups
Directing Effect of Substituents: meta-Directing Groups
Directing and Steric Effects in Disubstituted Benzene Derivatives
Nomenclature of Aromatic Compounds with Multiple Substituents
For disubstituted benzene derivatives, with two groups attached to the benzene ring, three constitutional isomers are possible. For example, consider dimethyl benzene, often called xylene, where the second methyl group can be substituted at the second, third, or fourth carbon. The relative position of the substituents is represented by prefixes ortho, meta, or...
NMR Spectroscopy of Benzene Derivatives
