Procedures on the Estimation of the Novel Quantitative Structure-Activity Relationship (QSAR) Descriptor σ_S° for Poly-Substituted Benzene Series, and Their Polarizabilities

Abstract

Procedures for the estimation of the novel quantitative structure-activity relationship (QSAR) descriptor σ_S°, representing the contributions from both dispersion and repulsion interactions, have been presented for the poly-substituted benzene derivatives.Observed values σ_S° for C₆H_6-nR_n (R=F, Cl, Me, Et : n=2-6)can be given by the equation σ_S°(R_n)=a log n+b, where the slope a and the intercept b are also linear against σ_S°(mono). Consequently, the slope a and the intercept b estimated from σ_S°(mono) and log n afford σ_S° for poly-substituted benzene derivatives having an optional set of substituent groups. The values thus obtained agreed well with the observed ones, and were also found to be linear against Σσ_S°(mono), where the correction of the number of symmetry should be taken into account.Furthermore, the net increases of polarizabilities Δα for the tetra-, penta-, and hexa-substituted benzene series from benzene reference are approved to be expressed by the linear relation against ΣΔα(mono).