Highly Efficient Alkane Oxidation Catalyzed by [Mn(N)(CN)]. Evidence for [Mn(N)(O)(CN)] as an Active Intermediate.
The oxidation of various alkanes catalyzed by [Mn(N)(CN)] using various terminal oxidants at room temperature has been investigated. Excellent yields of alcohols and ketones (>95%) are obtained using HO as oxidant and CFCHOH as solvent. Good yields (>80%) are also obtained using (NH)2[Ce(NO)] in CFC...
| Publicado en: | Journal of the American Chemical Society Vol. 136; no. 21; pp. 7680 - 7688 |
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| Autores principales: | , , , , , , , |
| Formato: | Artículo |
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American Chemical Society
5/28/2014
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=96519654&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 96519654 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 5/28/2014 vid: 136 iid: 21 pid: 997 pub: American Chemical Society artinfo: ui: 96519654 10.1021/ja5019546 ppf: 7680 ppct: 8 formats: tig: atl: Highly Efficient Alkane Oxidation Catalyzed by [Mn(N)(CN)]. Evidence for [Mn(N)(O)(CN)] as an Active Intermediate. aug: au: Li Ma Yi Pan Wai-Lun Man Hoi-Ki Kwong Lam, William W. Y. Gui Chen Kai-Chung Lau Tai-Chu Lau affil: Department of Biology and Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Hong Kong, China su: Oxidation of alkanes Oxidation Manganese compounds Cyclohexane Density functional theory sug: subj: Oxidation of alkanes Oxidation Manganese compounds Cyclohexane Density functional theory ab: The oxidation of various alkanes catalyzed by [Mn(N)(CN)] using various terminal oxidants at room temperature has been investigated. Excellent yields of alcohols and ketones (>95%) are obtained using HO as oxidant and CFCHOH as solvent. Good yields (>80%) are also obtained using (NH)2[Ce(NO)] in CFCHOH/HO. Kinetic isotope effects (KIEs) are determined by using an equimolar mixture of cyclohexane (c-CH) and cyclohexane-d (c-CD) as substrate. The KIEs are 3.1 ± 0.3 and 3.6 ±0.2 for oxidation by HO and Ce(IV), respectively. On the other hand, the rate constants for the formation of products using c-CH or c-CD as single substrate are the same. These results are consistent with initial rate-limiting formation of an active intermediate between [Mn(N)(CN)] and HO or Ce, followed by H-atom abstraction from cyclohexane by the active intermediate. When PhCHC(CH)OOH (MPPH) is used as oxidant for the oxidation of c-CH, the major products are c-CHOH, c-CHO, and PhCHC(CH)OH (MPPOH), suggesting heterolytic cleavage of MPPH to generate a Mn-O intermediate. In the reaction of HO with [Mn(N)(CN)] in CFCHOH, a peak at m/z 628.1 was observed in the electrospray ionization mass spectrometry, which is assigned to the solvated manganese nitrido oxo species, (PPh)[Mn(N)(O)(CN)]∙CFCHOH. On the basis of the experimental results the proposed mechanism for catalytic alkane oxidation by [Mn(N)(CN)]/ROOH involves initial rate-limiting O-atom transfer from ROOH to [Mn(N)(CN)] to generate a manganese(VII) nitrido oxo active species, [Mn(N)(O)(CN)], which then oxidizes alkanes (R'H) via a H-atom abstraction/O-rebound mechanism. The proposed mechanism is also supported by density functional theory calculations. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2014 holdings: @attributes: islocal: N |
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