6859-47-8Relevant academic research and scientific papers
The Study of Mg(II) Ion Influence on Catechol Autoxidation in Weakly Alkaline Aqueous Solution
Nikoli?,?ivanovi?,Krsti?,Nikoli?
, p. 2656 - 2660 (2020/01/23)
Abstract: High performance liquid chromatography with diode array detection (HPLC-DAD) and electron spin resonance (ESR) spectroscopy were used to study Mg(II) ion influence on the autoxidation of catechol in weakly alkaline solution. The presence of Mg(II) ions greatly enhanced the catechol autoxidation rate and probably influenced the mechanism of reaction thus enabling formation of reaction products not obtained in the absence of metal ions. Consecutive formation of 1,2-benzoquinone, 2,3-oxanthrenediol, and 2,3-oxanthrenedione with intermediate o-semiquinone anion radicals during the initial stages of catechol autoxidation was suggested based on the detailed analysis of experimental HPLC-DAD and ESR data. The results of this study may help in better understanding of autoxidation of some biologically important catecholic molecules in real systems, where Mg(II) ions are ubiquitously present. Because of the possible toxicity of simple quinone molecules, it is important that the formation of relatively stable quinoid autoxidation products were detected in this study.
94. Synthesen von Dibenzodioxin-2,3-chinonen, einschliesslich der Ecklonochinone A und B sowie der Isoecklonochinone A und B
Luetolf, Walter Leo,Prewo, Roland,Bieri, Jost H.,Ruedi, Peter,Eugester, Conrad Hans
, p. 860 - 881 (2007/10/02)
Syntheses of Dibenzodioxin-2,3-quinones Including the Ecklonoquinones A and B and the Isoecklonoquinones A and B.Oxidation of monomesyloxy-substituted pyrocatechols with MnO2 in toluene using phase-transfer conditions leads in high yield to monomesyloxy-substituted dibenzodioxin-2,3-quinones with loss of one mesyloxy group.In this way, ecklonoquinone A (2), ecklonoquinone B (3), isoecklonoquinone A (43), and isoecklonoquinone B (44) were prepared.Their structures are based on X-ray analyses of ecklonoquinone-A leucoacetate (45) and the mesyloxy-substituted quinone 20.The reddish-violet dibenzodioxin-diquinone 49 was prepared from an intermediate of the iso-series.The parent compound 1 has been synthesized in yields better than 50percent from pyrocatechol and methyl 2,5-dioxo-2,5-dihydrobenzoate as oxidant and 2-methoxypyridin as catalyst.To rationalize the specific effect on the dimerisation step of the mesyloxy group, the intermediacy of 1,4-quinone monoacetals is proposed.This also applies to a proposed biogenetic scheme.
