How accurate are physical property estimation programs for organosilicon compounds?
Organosilicon compounds are important in chemistry and commerce, and nearly 10% of new chemical substances for which Premanufacture Notifications (PMNs) are processed by the US EPA contain Si. Despite this, remarkably few measured values are submitted for key physical properties, and the accuracy of estimation programs like the Estimation Programs Interface (EPI) Suite and SPARC Performs Automated Reasoning in Chemistry (SPARC) is largely unknown. To address this we developed an extensive database of measured property values for organic compounds containing Si, then evaluated the performance of free estimation programs for several properties of importance in environmental assessment. These included melting point (MP), boiling point (BP), vapor pressure (VP), water solubility, n‐octanol/water partition coefficient (log Kow), and Henry's Law constant. For BP and the larger of two VP data sets, SPARC, MPBPWIN and EPA's Toxicity Estimation Software Tool (TEST) had similar accuracy. For log Kow and water solubility we tested 11 and 6 free estimators, and the best performers were Molinspiration and WSKOWWIN, respectively. TEST's consensus MP method outperformed that of MPBPWIN by a considerable margin. Generally, the best programs estimated the listed properties of diverse organosilicon compounds with accuracy sufficient for chemical screening. The results also highlight areas where improvement is most needed. Environ Toxicol Chem © 2013 SETAC