| Abstract
| - The unique nitration of the carbamate fungicide diethofencarb (Powmyl, isopropyl 3,4-diethoxycarbanilate) was examined in 14 Japanese soils and three types of clays under the aerobic conditionsusing the 14C-labeled compound. Nitration at the 6-position of the 3,4-diethoxyphenyl ring was aclay-catalyzed reaction and extremely enhanced under the dry conditions. Kinetic and product analysison nitration of nine 14C-labeled carbamate analogues in the kaolinite thin layer showed the nitrationproceeding electrophilically. Requirement of molecular oxygen and retardation of nitration by radicalscavengers and spin-trap reagents together with semiempirical AM1 molecular orbital calculationsstrongly suggested contribution of a radical mechanism, and these different speculations on thereaction mechanism might originate from the heterogeneous reaction environment on clay. Keywords: Nitration; clay mineral; abiotic transformation
|
