Synthesis and bioactivity of some fluorine-containing benzoyl arylureas. Part II: Insecticidal products in which the aryl group bears a polyfluoroalkoxy or (polyfluoroalkoxy)alkoxy side chain

This paper reports the synthesis and insecticidal activities of benzoyl arylureas in which the aryl group bears a polyfluoroalkoxy or (polyfluoroalkoxy)alkoxy side-chain. The activity of these compounds has been evaluated against larvae of S. littoralis, A. aegypti and L. decemlineata. The effects have been studied of varying (a) the substituents, R1 and R₂ in the 2-and 6-positions of the benzoyl moiety; (b) the polyfluoroalkoxy chain R₁ in the 4-position of the aryl moiety; and (c) the other substituent(s), R3, on this ring. In general, the highest activities were achieved against S. littoralis when R₁, R₂ = F, R₃ = 2-F and R₁ = O? CF₂CFH? OCF3 or R₁ = Cl and R₂ = H. R₃ = 2-Cl and R₁ = O? CF₂CFH? OCF₃; against A. aegypti when R₁, R₂ = F. R₃ = 3-F and R₁ = O? CF₂CFH? OCF₃ or R₁ = Cl and R₂ = H. R₃ = 3-F and R₁ = O? CF₂CFH? OCF₃; and against L. decemlineata by compounds in which R₁ = Cl and R₂ = H. R₃ = 3. 5-CI and R₁ = O? CF₂CFH? OCF₃, R₁, R₂ = F, R₃ = 3.5-Cl and R₁ = O? CF₂CFH? OCF₂CF₃, R₁, R₂ = F, R₃ = 3-CI and R₁ = O? CF₂CFH? OCF₂CF₂CF₃. The greatest overall insecticidal activities were achieved when R₁, R₂ = F, R₃ = 2-F and R₁ = O? CF₂CFH? OCF₃ and when R₁, R₂ = F, R₃ = 3-Cl and R₁ = O? CF₂CFH? OCF₃.     

Synthesis and insecticidal activity of lipophilic amides. Part 3: Influence of chain length and terminal group in N-(2-methylpropyl)-2,4-dienamides

Increasing the alkylene chain length in N-(2-methylpropyl)-ω-phenylalka-2,4-dienamides revealed in addition to the active compounds reported earlier a second peak of activity, but only against mustard beetles, with the tridecadienamide. Similar extension in the methyl-terminated series gave much weaker peaks, at different lengths for the two test species. Results with terminal vinyl compounds were intermediate, and indicated a specific functional role in the lethal process for the terminal unsaturation, with a possible contribution to steric flexibility and physical property optimisation from the longer chains. Synthetic samples of pellitorine and pipercide, natural products to which insecticidal activity has been ascribed, were only very weakly active in the present tests, but compounds with other groups on the ends of chains nearer the optimum length were more active.     

Synthesis and insecticidal activity of lipophilic amides. Part 4: The effect of substituents on the phenyl group of 6-phenylhexa-2,4-dienamides

Substituted phenylacetaldehydes, made by homologation of the benzaldehydes by Wittig condensation with a methoxymethylene ylid, were condensed under Wadsworth-Emmons conditions to give the substituted N-(2-methylpropyl)-6-phenylhexa-2,4-dienamides. Electron withdrawing substituents favoured the formation of the unwanted 3,5-diene isomer. Insecticidal activity was lowered by most substituents examined, but was retained or even enhanced by halogen atoms at the m- or p-positions. At the m-position, activity decreased as size of halogen increased.     

Degradation of dicarboximidic fungicides in wine. Part II: Isolation and identification of the major breakdown products of chlozolinate,vinclozolin and procymidone

The main degradation products formed from the dicarboximidic fungicides chlozolinate, vinclozolin and procymidone in wine have been isolated and identified using spectroscopic and chromatographic methods. The fungicides were added to wine after fermentation. Chlozolinate underwent a rapid hydrolytic loss of the ethoxy-carbonyl substituent, to give an oxazolidine that underwent hydrolytic cleavage to give 3′,5′-dichloro-2-hydroxypropanilide. The oxazolidine ring of vinclozolin underwent a similar hydrolysis to give the corresponding anilide 3′,5′-dichloro-2-hydroxy-2-methylbut-3-enanilide. Both these anilides were stable in wine for 150 days. A different degradation behaviour was observed with procymidone and led to the formation of 3,5-dichloroaniline (3,5-DCA), which, in turn, broke down but the derivatives could not be isolated. After consideration of the different behaviours of the fungicides on degradation in wine and in aqueous ethanol at pH4, together with their kinetic data, breakdown pathways are proposed.     

Studies of the New Herbicide KIH-6127. Part I. Novel Synthesis of Methyl 6-Acetylsalicylate as a Key Synthetic Intermediate for the Preparation of 6-Acetyl Pyrimidin-2-yl Salicylates and Analogues

A novel synthesis of methyl 6-acetylsalicylate as a key synthetic intermediate for methyl 2-[(4,6-dimethoxypyrimidin-2-yl)oxy]-6-[1-(methoxyimino)ethyl]benzoate (KIH-6127) was studied, and directed at 6-substituted pyrimidin-2-yl salicylate herbicides and their analogues. Three synthetic approaches were successful: a modification of the Sandmeyer reaction of 6-acetylanthranilate (Method A), a direct ring-opening reaction of 3-methylphthalide using potassium permangamate and magnesium nitrate (Method B), and a regioselective ortho-lithiation of the protected 3-hydroxyacetophenone (Method C). These methods were applicable for the synthesis of various 6-acyl salicylates.     

Studies into the action of the diphenyl ether herbicides acifluorfen and oxyfluorfen. Part I: Activation by light and oxygen in leaf tissue

The effect of acifluorfen and oxyfluorfen on chlorophyll bleaching, lipid peroxidation and photosynthesis in pea leaf discs was studied. Both her- bicides induced light-dependent bleaching and lipid peroxidation, the level of damage being greater at higher light intensities. Photosynthetic carbon dioxide fixation was only partially inhibited in treated leaf discs incubated in darkness, thus indicating that these herbicides did not inhibit photo- synthesis as a primary mode of action. Leaf discs maintained in darkness showed no visible signs of injury, and light-dependent herbicide-induced damage was reduced by incubating discs under nitrogen, orpre-incubating them with the electron-transport inhibitor monuron. It is suggested that acifluorfen and oxyfluorfen are activated by a light-dependent process, which requires photosynthetic electron transport.     

Studies of the mechanism of action of asulam in plants. Part I: Antagonistic interaction of asulam and 4-aminobenzoic acid

Studies have been carried out on the herbicidal action of asulam [methyl (4-aminophenylsulphonyl)carbamate] and sulphanilamide, alone or in association either with 4-aminobenzoic acid (4ABA) or 4, 6-diamino-1-(3, 4-dichlorophenyl)-1, 2-dihydro-2, 2-dimethyl-1,3,5-triazine (DCDT). The soaking of wheat seeds (Triticum estivum L.) for 12 h at 30°C in asulam and DCDT in a 10:1 ratio doubled the inhibition of root growth produced by soaking in asulam alone; the addition of 4ABA partially reversed the activity of asulam. Foliar applications of a mixture of asulam + DCDT (1.1 + 0.55 kg ha^?1) markedly increased the activity of asulam in susceptible wheat, wild oat (Avena fatua L.), tolerant flax (Linum usitatissimum L.), and in Stellaria media L. The activity of asulam at 1.1 kg ha^?1 was reversed by 4ABA at 2.2 kg ha^?1 by about 50% in wheat and wild oat, 82% in flax and 100% in S. media. The results indicate that asulam and sulphanilamide act by similar mechanisms in apparently inhibiting the biosynthesis of folic acid.     

Synthesis and insecticidal activity of lipophilic amides. Part 2: Effect of heteroatom replacements and of introducing methyl groups in the pentadiene system

Following the discovery of insecticidal activity in (2E,4E)-N-(2-methylpropyl)-6-phenylhexa-2,4-dienamide, structural analogues containing variations of the central pentadiene system have been examined. They include the five compounds with extra methyl groups on each of the five carbons in turn, and compounds in which heteroatoms have been introduced instead of, or additional to, the original CH or CH₂ groups. All were insecticidally inactive, indicating for the first time the severe limitations on this group if activity is to be retained.     

Pesticide residues in foodstuffs in England and Wales. Part II: Inorganic bromide ion in cucumber,tomato and self-blanching celery grown in soil fumigated with bromomethane,and the ‘natural’ bromide ion content in a range of fresh fruit and vegetables

Surveys of inorganic bromide ion residues in tomatoes, cucumbers and selfblanching celery, commercially produced in England following soil sterilisation with bromomethane, have been carried out since 1979. The mean bromide ion level in 29 late-season cucumber samples was approximately 28 mg kg⁻¹ and ranged up to 109 mg kg⁻¹. Analysis of 242 tomato samples gave estimated mean bromide ion levels per plant ranging from 6 to 187 mg kg⁻¹ in fruit picked throughout the season from seven holdings, on six of which bromomethane had been used fairly recently prior to planting. A statistically significant fall in bromide levels over the growing season was shown on four of the sites. In 38 samples of self-blanching celery, the mean bromide ion level was 104 mg kg⁻¹ even though the mean interval between fumigation and planting was in excess of 1 year. Retail surveillance indicated that a large number of crops are likely to have bromide ion levels below 10mg kg⁻¹.