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(T/MF154) Estimation of pH dependent hydrolysis rates. Quas, Lutz1, Strauch, Peter2, Kühne, Ralph1, Schüürmann, Gerrit1, 1 2 ABSTRACT- To estimate the environmental fate of chemicals, degradation rates in the environmental compartments are required. In water, hydrolysis is considered as an important degradation pathway. Hydrolysis may be catalysed by either acids or bases. The effective reaction rate is a superimposition of the neutral process (kn), the base catalysed process (kb), and the acid catalysed process (ka): kh = kn + ka[H+] + kb[OH-]. A new model is developed to predict the hydrolysis reaction rate from molecular structures in the entire pH range for any organic compounds containing degradable functional groups. This technique is in contrast to other currently available methods, considering only one of the partial reactions for each compound. The new model works well for esters, amides, carbamates, epoxides and haloalkanes. The results are compared with experimental data, and with alternative calculation methods. Key words: hydrolysis rate, pH dependency, estimation method |
