APPLICATION OF CHEMOMETRICS TO THE SCREENING OF HAZARDOUS SUBSTANCES .2. ADVANCES IN THE MULTIVARIATE CHARACTERIZATION AND REACTIVITY MODELING OF HALOALKANES

This paper updates a quantitative structure-activity relationship pres ented previously, where the rate constant of the gas-phase reaction be tween hydroxyl radical and haloalkanes, k(OH), was related to six atom -counting variables. Five new, group-counting variables have been incl uded in the structural parametrization; they describe the variations i n the substitution pattern at the reaction centers (the C-H groups in the molecules). The updated model, contrary to the original, permits o ne to distinguish between isomeric structures, and is applicable to th e previous outliers group of the CH3-C(X)3 (X = halogen) structures. I t shows a remarkable predictive capability for new compounds ('externa l' Q2 = 0.86) over the examined X and Y ranges of the series, and work s with descriptors which can be drawn directly from the structures.