Hydrolysis reaction mechanism in atrazine metabolism and prediction of its metabolites' toxicities.

Atrazine (ATR) is a widely used herbicide. There are several types of reactions in its metabolism. Herein, the mechanism of three paths of hydrolysis reactions in its metabolism and predictions of toxicities of its metabolites in the three paths will be presented. The calculation results by B3LYP (Becke, 3-parameter, Lee-Yang-Parr), one of the approaches in density functional theory, indicated that (1) there were three models in the three hydrolysis paths of ATR. The dissociation mechanisms of C(9/11)-N(8/10), C(4/6)-N(8/10), and C-Cl were dealkylation, deamination, and Cl substitution, respectively. (2) The energy barrier of C-Cl dissociation was lower. The dissociation was advantageous in dynamics and the primary reaction in the three hydrolysis paths. In these hydrolysis reactions, the different intermediates had different concentrations because of the impact of the reaction rate. (3) In addition, it was necessary to consider the solvent effect to investigate hydrolysis reaction. The conductor-like polarizable continuum model (CPCM) was used to simulate the hydrolysis reaction in bond length and energy barrier because of the solvent effect. Experimental or predictive results showed that atrazine and its metabolites in the three hydrolysis paths were carcinogenic.