Clay-catalyzed nitration of a carbamate fungicide diethofencarb.
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 conditions using the (14)C-labeled compound. Nitration at the 6-position of the 3,4-diethoxyphenyl ring was a clay-catalyzed reaction and extremely enhanced under the dry conditions. Kinetic and product analysis on nitration of nine (14)C-labeled carbamate analogues in the kaolinite thin layer showed the nitration proceeding electrophilically. Requirement of molecular oxygen and retardation of nitration by radical scavengers and spin-trap reagents together with semiempirical AM1 molecular orbital calculations strongly suggested contribution of a radical mechanism, and these different speculations on the reaction mechanism might originate from the heterogeneous reaction environment on clay.
Kodaka
Rika
R
Sumitomo Chemical Company, Ltd., Environmental Health Science Laboratory, 2-1, Takatsukasa 4-chome, Takarazuka 665-8555, Japan. kodaka@sc.sumitomo-chem.co.jp
Sugano
Terumi
T
Katagi
Toshiyuki
T
Takimoto
Yoshiyuki
Y
D000538:Aluminum Silicates / Q000737:chemistry*; D002219:Carbamates / Q000737:chemistry*; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D000077215:Clay; D005659:Fungicides, Industrial / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry*; D048448:Phenylcarbamates; D012987:Soil
D000538:Aluminum Silicates; D002219:Carbamates; D005659:Fungicides, Industrial; D009566:Nitrates; D048448:Phenylcarbamates; D012987:Soil; C070961:diethofencarb; D000077215:Clay