Effect of ortho-chlorine substitution on the partition behavior of chlorophenols.

Institute of Biogeochemistry and Pollutant Dynamics, ETH-Zurich, Universitätsstrasse 16, CH-8092 Zurich, Switzerland.

Chlorophenol isomers are known to possess substantially different octanol/water and octane/water partition constants depending on whether the chlorine substituents are in the ortho or meta/para position. Here we show that the same is also true for environmental partition processes such as water/air and humic acid/air partitioning. Quantitative structure property relationships (QSPR) such as those in the widely used EPI-suite or SPARC fail to correctly predict this influence of the substituent position on the compound's partitioning. Only a more sophisticated quantum chemical software, called COSMOtherm, correctly reproduced these effects. Based on this and earlier experiences we conclude that COSMOtherm may be a better tool for screening large sets of chemicals for which no experimental data on their partitioning yet exist.

PMID: 18068754 [PubMed - indexed for MEDLINE]