Abiotic degradation in the water phase

Estimation methods for the hydrolysis rates of several types of carboxylic acid esters, carbamates, aromatic nitriles and phosphoric acid esters have been reported. Hydrolysis rates are subject to substituent effects, and consequently linear free-energy relationships (LFERs), as represented by Hammett or Taft correlations, have hence been applied to their estimations. Reviews (e.g. Harris, 1990 Peijnenburg, 1991) reveal that QSARs are available for only a few compound classes (Table 4.8) and are mostly based on limited sets of experimental data. 

Several QSARs, developed for different purposes, are not applicable for environmental hazard assessment as the underlying transformation rates were obtained not in water but in a mixture of solvents. Further development is needed, therefore, especially with respect to validation and extension of the existing QSARs, the derivation of new QSARs for extra compound classes and the consideration of the various mechanisms of hydrolysis. 

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