SYNTHESIS OF C14-LABELED SIDURON AND ITS FATE IN SOIL

Radioactive siduron, 1-(2-methylcyclohexyl)-3-phenyl-2-C14-urea, was synthesized with anoverall yield of approximately 80% by reacting 2-methylcyclohexylamine with C14-carbonyl-labeled phenylisocyanate made from the correspondingly labeled benzoic acid via its azide. Labeled siduron was used in a study to measure its rate of disappearance, penetration, and mode of decomposition in soil. The results confirmed previous field data, showing that siduron resists leaching, remains in the top layer of the soil, and degrades at a moderate rate. The Rf values for the major siduron metabolites in soil were in good agreement with 1-(4-hydroxy-2-methylcyclohexyl)-3-(p-hydroxyphenyl)urea, 1-(4-hydroxy-2-methylcyclohexyl)-3-phenylurea, and 1-(p-hydroxyphenyl)-3-(2-methylcyclohexyl)urea, the three major metabolites isolated from the urine of a dog fed siduron. A fungus and two bacterial species (Pseudomonas sp.), capable of metabolizing siduron, have been isolated from soil. © 1969, American Chemical Society. All rights reserved.