Biomimetic oxidation of 3,5-di-tert-butylcatechol by dioxygen via Mn-enhanced base catalysis

TitleBiomimetic oxidation of 3,5-di-tert-butylcatechol by dioxygen via Mn-enhanced base catalysis
Publication TypeJournal Article
Year of Publication2006
AuthorsSzigyártó, ICs., Simándi, LI, Párkányi, L, Korecz, L, Schlosser, G
JournalInorganic Chemistry
Volume45
Issue18
Pagination7480 - 7487
Date Published2006
ISBN Number00201669 (ISSN)
Keywords2 benzoquinone, 2-benzoquinone, 3,5 di tert butylcatechol, 3,5-di-tert-butylcatechol, Article, benzoquinone derivative, Benzoquinones, biomimetics, catalysis, catechol derivative, Catechols, chemical structure, chemistry, Crystallography, X-Ray, Kinetics, ligand, Ligands, Manganese, Models, Molecular, Molecular Structure, organometallic compound, Organometallic Compounds, oxidation reduction reaction, Oxidation-Reduction, oxygen, synthesis, X ray crystallography
Abstract

The 6-coordinate dioximatomanganese(II) complex [Mn(HL)(CH 3OH)]+ (2, where H2L is [HON=C(CH 3)C(CH3)=NCH2-CH2]2NH), formed by instant solvolysis of [Mn2(HL)2](BPh 4)2 (1) in methanol, accelerates the triethylamine (TEA)-catalyzed oxidation of 3,5-di-tert-butylcatechol (H2dtbc) by O2 to the corresponding o-benzoquinone. Significantly, 2 alone has no catalytic effect. The observed rate increase can be explained by the interaction of 2 with the hydroperoxo intermediate HdtbcO2 - formed from Hdtbc- and O2 in the TEA-catalyzed oxidation. The kinetics of the TEA-catalyzed and Mn-enhanced reaction has been studied by gas-volumetric monitoring of the amount of O 2 consumed. The initial rate of O2 uptake (Vin) shows a first-order dependence on the concentration of 2 and O2 and saturation kinetics with respect to both H2dtbc and TEA. The observed kinetic behavior is consistent with parallel TEA-catalyzed and Mn-enhanced oxidation paths. The 3,5-di-tert-butylsemiquinone anion radical is an intermediate detectable by electron spin resonance (ESR) spectroscopy. The dimeric catalyst precursor has been characterized by X-ray diffraction and electrospray ionization mass spectrometry and the monomeric catalyst by ESR spectroscopy. © 2006 American Chemical Society.

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Short TitleInorg. Chem.