Correlation analysis of substituent effects on the acidity of benzoic acids by the AM1 method

Theoretical analysis of the electronic effect of aromatic substituents was done with the use of the AM1 computational procedure. The gas‐phase acidity of substituted benzoic acids was linear with the difference in the heat of formation between corresponding benzoic acids and benzoate anions, the energy of the highest occupied molecular orbital, and the net charge on the acidic oxygen atoms of the corresponding benzoate anions. The Hammett σ constant was linearly correlated with the net charge on the atoms of the acid moiety of substituted benzoic acids. The AM1 computational procedure satisfactorily reproduced the electronic properties of a wide variety of substituents.