Estimation of the Liquid Viscosity of Organic Compounds with a Quantitative Structure-Property Model

A QSPR (quantitative structure-property relationship) model for the estimation of the liquid viscosity of a large variety of organic compounds was established using the CODESSA (comprehensive descriptors for structural and statistical analysis) approach. The final model was developed with a calibration set containing 337 compounds. The multilinear regression (MLR) equation that relates ln η to five molecular descriptors has s ) 0.37 and r ) 0.920. The five theoretical parameters used in the QSPR model are molecular weight, Randić connectivity index of order 3, hydrogen-donor charged surface area HDCA-2 (electrostatic), maximum electrophilic reactivity index for a carbon atom, and maximum atomic orbital electronic population. The predictive ability of the MLR model was tested by the leave-20%-out cross-validation method, showing that the QSPR model is stable and can be used to obtain good predictions for compounds that were not used in the model calibration. The cross-validation statistical indices show a small decrease when compared with those obtained in the calibration phase (scv ) 0.38, rcv ) 0.917). The QSPR models developed with CODESSA allow accurate computation of the liquid viscosity of organic compounds using simple constitutional descriptors and quantum indices which can be computed with standard quantum chemistry packages.