Structure-activity relationships for mono alkylated or halogenated phenols.

The quantitative structure-activity relationships between toxicity (log BR), monitored as cell population growth, and two molecular descriptors, the log 1-octanol/water partition coefficient (log Kow) and the Hammett sigma constant (sigma) or the ionization parameter (pKa) for a series of 17 ortho-, meta- and para-substituted alkylated or halogenated phenols have been examined. The equation: log BR = 0.7998 (log Kow) + 1.2447 (sigma) - 1.5538; r2 = 0.897 s = 0.170 has been found to be an excellent planar model for these chemicals. This model uses the para-position sigma constant as the estimator of ortho-position electronic effects. A similar equation: log BR = 0.7845 (log Kow) - 0.3702 (pKa) + 2.1144; r2 = 0.860 s = 0.199 has been developed using pKa in place of sigma.