A novel iron-enhanced pathway for base-catalyzed catechol oxidation by dioxygen |
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| Authors: | Zoltán May László I Simándi and and Attila Vértes |
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| Institution: | (1) Institute of Surface Science and Catalysis, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, PO Box 17, Hungary;(2) Institute of Surface Science and Catalysis, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, PO Box 17, Hungary;(3) Department of Nuclear Chemistry, L. E?tv?s University, Budapest, Hungary |
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| Abstract: | Summary The kinetics and mechanisms of the catecholase-type biomimetic activation of O2 by the new dioximatoiron(II) complexes Fe(Hdmed)]+, Fe(Hdmpd)]+ and Fe(H2dmdt)]2+ have been studied in methanol. Kinetic measurements reveal first order behavior with respect to catalyst and O2 and a saturation type dependence on the 3,5-di-tert-butylcatechol (H2dtbc) substrate. Added triethylamine increases the rate by changing the reaction mechanism. An important, hitherto unknown
feature is iron(II)-enhanced base catalysis of H2dtbc oxidation, via coordination of HdtbcO2- to the Fe(II) complex present, resulting in a significant acceleration of oxidation. A mechanism involving free radicals
is suggested on grounds of ESR evidence. The activity pattern of the catalyst complexes correlates with coordination number
and symmetry as revealed by M?ssbauer spectra. |
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| Keywords: | oxidation kinetics Biomimetic catalysis catechol oxidation dioximatoiron(II) M?ssbauer spectra |
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