Methyltrioxorhenium

Hudson, Andrew; Betz, Daniel; Kühn, Fritz E.; Jimenez-Aleman, Guillermo Hugo; Boland, Wilhelm

doi:10.1002/047084289x.rn00017.pub3

Cited by 3 publications

(2 citation statements)

References 131 publications

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“…The secondary building units (SBUs) are particularly relevant targets for functionalization because they can be thought of as nanoscale models of the metal oxides traditionally used as industrial catalyst supports. , Among supported OM catalysts, rhenium oxide-based systems stand out due to their activity at room temperature and their broad tolerance to a range of heterofunctionalized olefins when activated by main group alkyl species. ,, These characteristics contrast with molybdenum and tungsten systems, which are active only at significantly higher temperatures and are less tolerant of functionalized olefins. Important milestones in rhenium oxide chemistry were the discovery and efficient preparation , of methyltrioxorhenium (MTO), a molecule with diverse catalytic competency. − The most salient feature of this versatile model − for immobilized rhenium oxide species in the context of heterogeneous OM catalysis is its inability to catalyze this transformation until activated on an appropriate support. The surprisingly limited scope of supports capable of triggering OM activity from MTO include alumina, − silica–alumina, ,,− niobia, , and zeolite HY …”

Section: Introductionmentioning

confidence: 99%

Activation of Methyltrioxorhenium for Olefin Metathesis in a Zirconium-Based Metal–Organic Framework

et al. 2018

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The zirconium nodes of the metal-organic framework (MOF) known as NU-1000 serve as competent supports for the activation of methyltrioxorhenium (MTO) toward olefin metathesis. Itself inactive for olefin metathesis, MTO becomes an active catalyst only when immobilized on the strongly acidic Lewis acid sites of dehydrated NU-1000. Uptake of MTO at the dehydrated secondary building units (SBUs) occurs rapidly and quantitatively to produce a catalyst active in both gas- and liquid-phase processes. These results demonstrate for the first time the utility of MOF SBUs for olefin metathesis, an academically and industrially relevant transformation.

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Section: Introductionmentioning

confidence: 99%

Activation of Methyltrioxorhenium for Olefin Metathesis in a Zirconium-Based Metal–Organic Framework

et al. 2018

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“…Catalysts with activity for each of these respective steps were screened for their effect on epoxy matrix dissolution time. Methyltrioxorhenium (MTO [10]) and ascorbic acid (VC) were applied as OAT catalysts while Lewis acids scandium trichloride (ScCl 3 ) and aluminum trichloride (AlCl 3 , a ScCl 3 analog that appears elsewhere in the composites degradation literature [11]) were tested as elimination catalysts.…”

Section: Resultsmentioning

confidence: 99%

Mechanism and Catalysis of Oxidative Degradation of Fiber-Reinforced Epoxy Composites

Navarro

Kedzie

et al. 2018

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Carbon fiber-reinforced polymer (CFRP) materials are widely used in aerospace and recreational equipment, but there is no efficient procedure for their end-of-life recycling. Ongoing work in the chemistry and engineering communities emphasizes recovering carbon fibers from such waste streams by dissolving or destroying the polymer binding. By contrast, our goal is to depolymerize amine-cured epoxy CFRP composites catalytically, thus enabling not only isolation of high-value carbon fibers, but simultaneously opening an approach to recovery of small molecule monomers that can be used to regenerate precursors to new composite resin. To do so will require understanding of the molecular mechanism(s) of such degradation sequences. Prior work has shown the utility of hydrogen peroxide as a reagent to affect epoxy matrix decomposition [1]. Herein we describe the chemical transformations involved in that sequence: the reaction proceeds by oxygen atom transfer to the polymer’s linking aniline group, forming an N-oxide intermediate. The polymer is then cleaved by an elimination and hydrolysis sequence. We find that elimination is the slower step. Scandium trichloride is an efficient catalyst for this step, reducing reaction time in homogeneous model systems and neat cured matrix blocks. The conditions can be applied to composed composite materials, from which pristine carbon fibers can be recovered.

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