- Regioselectivity and stereoelectronic effects in the reactions of the dinitroaniline herbicides trifluralin and benefin with nucleophiles
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The reactions of two members of the dinitroaniline class of herbicides, N,N-di-n-propyl-2,6-dinitro-4-(trifluoromethyl)aniline (trifluralin; 1) and N-ethyl-N-n-butyl-2,6-dinitro-4-(trifluoromethyl)aniline (benefin; 2), along with their analogue, N-phenyl-2,6-dinitro-4-(trifluoromethyl)aniline (3), with the nucleophiles, OD- and SO32-, have been investigated using 400 MHz 1H NMR spectroscopy. The reactions of both 1 and 2 with OD- result in formation of Meisenheimer anionic σ-complexes according to a K3T1 (kinetic preference for formation of the C-3 adduct with thermodynamic preference for formation of the C-1 adduct) reaction sequence while the reaction of 3 with OD- and that of 1 with SO32- follow a K3T3 (kinetic and thermodynamic preference for formation of the C-3 adduct) sequence. There was no observation of the C-1 adducts of 1 and 2 with OD-, but the products of S(N)Ar displacement at C-1 were observed as the final thermodynamic products. Geometry optimization calculations support our hypothesis of n → σ* stabilization of the C-1 adduct leading to S(N)Ar displacement. In the reaction of 3 with OD-, initial N-deprotonation to form the anion, 3a, is followed by σ-complex formation. The final thermodynamic product observed in this system is 3,5-dinitro-4-(N-phenylamino)benzoic acid formed through hydrolysis of the trifluoromethyl group on the anion, 3a. Aryl H-D exchange has been found for the systems of 1 and 2 with OD-, but not for the SO32- system and neither for the reaction of 3 with OD-. Since dimethylpicramide showed significantly slower H-D exchange under identical conditions, it is argued that this discrepancy has as origin the ability of the amino N lone electron pair to interact with the π-system of the ring. With both 1 and 2 the larger size of the amino alkyl chains prevent the amino N lone pair from aligning with the π-system of the ring, thus hindering electron density donation to the electron-deficient ring carbons.
- Annandale, Michael T.,VanLoon, Gary W.,Buncel, Erwin
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p. 873 - 883
(2007/10/03)
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- Synergistic herbicidal compositions comprising 4-benzoylisoxazole and dinitroaniline herbicides
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The invention relates to synergistic compositions comprising: (a) a 4-benzoylisoxazole of formula (I) STR1 wherein R, R1, R2 and n are as defined in the specification; and (b) a dinitroaniline herbicide; and to the use of these compounds as herbicides.
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- 4-Trifluoromethyl-2,6-dinitroanilines
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This invention relates to a group of novel substituent anilines, useful in eliminating germinating and seedling weed grasses and selected broadleaf weeds.
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- 4-Trifluoromethyl-2,6-dinitroanilines
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This invention relates to a group of novel substituent anilines, useful in eliminating germinating and seedling weed grasses and selected broadleaf weeds.
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- Plant-protective and pest-control agent
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A herbicidal composition capable of preventing weed growth of potatoes or soybean plants consists of a triazene or an aromatic nitro compound together with an inorganic salt, especially sodium bisulfate or potassium bisulfate which reduced the quantity of the organic herbicide below that usually required to obtain a corresponding herbicidal effect and hence prevents phytotoxic damage. The composition contains 0.1:1 to 15:1 parts by weight of the inorganic compound to the organic compound and is applied in an amount of 0.1 to 30 kg of the composition per hectare.
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- Removal of nitrosamines from denitroanilines by treatment with HCl
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The present invention is directed to a process for the removal of nitrosamines from dinitroanilines.
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