par Rouchaud, Jean;Gustin, Fabrice;Moulard, Claude 
Référence Bulletin des Sociétés chimiques belges, 101, 11, page (959-968)
Publication Publié, 1992
Référence Bulletin des Sociétés chimiques belges, 101, 11, page (959-968)
Publication Publié, 1992
Article révisé par les pairs
| Résumé : | Heating to reflux the imidazolin‐4‐one arylcarboxylate herbicide imazamethabenz 1 (methyl 2‐(4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1H‐imidazol‐2‐yl)‐4‐(in mixture with the 5‐isomer) methylbenzoate) in KOH in water, or in HCl or H2SO4 in water, or in HCl in acetic acid+ water hydrolyzed only the methylcarboxylate function, yielding 2‐(4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1H‐imidazol‐2‐yl)‐4‐(in mixture with the 5‐isomer) methyl‐benzoic acid (2). The imidazolin‐4‐one ring thus remained intact in all the assayed hydrolysis conditions. The oxidation reagents acetic acid+acetic anhydride+KMnO4, or acetic acid+CrO3 left imazamethabenz untransformed; the first reagent however transformed a part of imazamethabenz into its N‐acetyl derivative (5). The oxidation reagent water+Na2CO3+ KMnO4 hydrolyzed the carboxylate of imazamethabenz, and oxidized the methyl substituent on the benzene ring, giving 2‐(4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐lH‐imidazol‐2‐yl)‐1,4‐(in mixture with the 1,5‐isomer)‐benzenedicarboxylic acid (3). The oxidation reagent water containing H2SO4+Na2Cr2O7 however gave 1,2,4‐benzenetricarboxylic acid (4)(in mixture with the 1,2,5‐isomer), which corresponded to the simultaneous oxidation and hydrolysis of the imidazolin‐4‐one ring. All these trials thus showed the high resistance of the imidazolin‐4‐one ring towards hydrolysis and oxidation; it probably was due to its tautomeric equilibrium with the fully aromatic hydroxy form (transformed into the potassium hydroxylate salt in basic medium), and to its nitrogen atoms protonation in acid medium. Copyright © 1992 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim |
