1. The metabolic fate of the insecticide diflubenzuron was investigated in the rat with radioactively labelled forms of the compound. 2. Intestinal absorption, measured as the sum of urinary and biliary excretion, diminished greatly with increasing dose, from about 50% at 4 mg/kg to about 4% at 900 mg/kg. 3. Excretion was almost complete at 72 h after dosing. At that time up to 4% of a dose was recovered from the carcasses of the rats. No detectable excretion of radioactive CO2 occurred (less than 0.5% of dose). 4. The metabolic pattern in urine and bile was investigated with diflubenzuron labelled with both 3H and 14C. No unchanged compound was detected. About 80% of the metabolites appeared to have the basic diflubenzuron structure intact. Three of these, hydroxylated at either aromatic ring, were identified; they were largely excreted as conjugates in the bile. The remainder, also largely excreted in the bile, constituted very polar material. About 20% of the diflubenzuron underwent scission of the ureido bridge. One scission product, 2,6-difluorobenzoic acid, was largely excreted as such in the urine. Its counterpart, 4-chlorophenylurea, was not present in urine or bile in appreciable quantity; nor was 4-chloroaniline detected.
2,6-Difluorobenzoic acid, one of the two primary dijlubenzuron metabolites, is rapidly and completely degraded in soil. Times to 50 % disappearance were 9 and 12 days in two agricultural soils. [14C]Carbon dioxide was an ultimate product of the ring-14C-labelled compound. A part of the radioactivity, increasing with time to one third of the applied dose of I mg k g -' , could not be extracted ffom the soil.
The fate of 4‐chlorophenylurea in soils was studied with two preparations: one labelled with 14C in the phenyl ring and the other in the carbonyl group. The initial dose of 1 mg kg−1 decreased to 50% in about 5 weeks in aerobic sandy clay and in about 16 weeks in anaerobic hydrosoil. Soil treatment with each of the preparations resulted in the release of [14C]carbon dioxide, pointing to decarbonylation and ring opening. The fraction of non‐extractable (soil‐bound) radioactivity increased during incubation. Quantities of ring‐14C‐labelled and carbonyl‐14C‐labelled bound residues differed strongly in the aerobic soil but only slightly in the anaerobic hydrosoil. It is assumed that two sorts of bound residues are formed from 4‐chlorophenylurea: one is fairly stable and might consist of bound 4‐chloroaniline or its transformation products, whereas the other is presumed to be a degradable derivative of 4‐chlorophenylurea.
The synthesis of 38 compounds with structure R-SOn-CHe-SCN, in which R is a heterocyclic radical and n = 0, 1 , or 2 , is described and their fungicidal and phytotoxic activities are discussed.
IntroductionAs described and discussed in a previous paper from these Laboratories, arylsulfonyl-and arylsulfinyl-methyl thiocyanates showed high fungicidal activity, combined with low phytotoxicity. Those properties make these compounds very useful for phytopharmaceutical application. In continuation of this investigations a number of compounds of this type with an aromatic heterocyclic radical was synthesized and screened for fungicidal activity.
The reaction of dimethyl azodiformate with 1-phenylcyclopentene, 1 -phenylcyclohexene, I-(2-naphthyl)cyclopentene, I-(2-naphthyl)cyclohexene, 1-(6-rnethoxy-2-naphthy1)cyclopentene and 1-(6-methoxy-2-naphthyI)cyclohexene gives 2 : 1 (ester-olefin) adducts. The reaction mechanism of adduct formation is discussed.A convenient method of preparing six-membered heterocycles is via the Diels-Alder reaction 4 9 5 . One of the earliest examples of the Diels-Alder reaction is in fact the formation of heterocyclic system 1 by the addition of azodiformic ester to cyclopentadiene G .
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