GAS-PHASE ATMOSPHERIC CHEMISTRY OF SELECTED THIOCARBAMATES

The kinetics and products of the gas-phase reactions of OH radicals, NO3 radicals, and O3 with the thiocarbamates S-methyl N,N-dimethylthiocarbamate (MDTC), S-ethyl NN-dipropylthiocarbamate (EPTC), and S-ethyl N-cyclohexyl-N-ethylthiocarbamate (cycloate) have been studied at 298 +/- 2 K and approximately 735 Torr air. By use of relative rate techniques, all three thiocarbamates were observed to react with OH and NO3 radicals, with the following respective reaction rate constants (in cm3 molecule-1 s-1): MDTC, 1.33 X 10(-11) and 7.3 x 10(-15); EPTC, 3.18 x 10(-11) and 9.2 x 10-(15); cycloate, 3.54 x 10(-11) and 3.29 X 10(-14). No reactions with O3 were observed, and upper limits to the rate constants (cm3 molecule-1 s-1) were determined: MDTC, < 4 X 10(-20); EPTC, < 1.3 X 10(-19); cycloate, < 3 X 10(-19). These kinetic data indicate that the OH radical reactions are the dominant atmospheric loss process for these gas-phase thiocarbamates.