Computational study on the kinetics and mechanism of the carbaryl + OH reaction.

Carbaryl is released into the atmosphere as a spray drift immediately following the application. In order to evaluate its fate in the atmosphere, a computational study on the kinetics of the OH radical reaction with carbaryl is presented. Different reaction paths are studied at the M05-2X/6-311++G(d,p) level. A complex mechanism involving the formation of a stable reactant complex is proposed and the temperature dependence of the rate coefficients is studied in the 280-650 K temperature range. The principal degradation path is the hydroxyl radical addition to naphthalene, but hydrogen abstractions from the methyl group are identified as a secondary significant path. The rate coefficients, computed using the conventional transition state theory, reproduce quite well the scarce experimental data available.