Catalytic Alkane Metathesis by Tandem Alkane Dehydrogenation-Olefin Metathesis

Goldman, Alan S.; Roy, Amy H.; Huang, Zheng; Ahuja, Ritu; Schinski, William L.; Brookhart, Maurice

doi:10.1126/science.1123787

Cited by 560 publications

(357 citation statements)

References 18 publications

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“…This does not have to be the case. As has recently been demonstrated, metal complexes working in tandem can promote reactions of energy consequence (62). Accordingly, the water-splitting schemes may be accomplished by two different metal complexes working in concert.…”

Section: Methodsmentioning

confidence: 96%

Powering the planet: Chemical challenges in solar energy utilization

Lewis

Nocera

2006

Proc. Natl. Acad. Sci. U.S.A.

7,582

5,540

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Global energy consumption is projected to increase, even in the face of substantial declines in energy intensity, at least 2-fold by midcentury relative to the present because of population and economic growth. This demand could be met, in principle, from fossil energy resources, particularly coal. However, the cumulative nature of CO 2 emissions in the atmosphere demands that holding atmospheric CO 2 levels to even twice their preanthropogenic values by midcentury will require invention, development, and deployment of schemes for carbon-neutral energy production on a scale commensurate with, or larger than, the entire present-day energy supply from all sources combined. Among renewable energy resources, solar energy is by far the largest exploitable resource, providing more energy in 1 hour to the earth than all of the energy consumed by humans in an entire year. In view of the intermittency of insolation, if solar energy is to be a major primary energy source, it must be stored and dispatched on demand to the end user. An especially attractive approach is to store solar-converted energy in the form of chemical bonds, i.e., in a photosynthetic process at a year-round average efficiency significantly higher than current plants or algae, to reduce land-area requirements. Scientific challenges involved with this process include schemes to capture and convert solar energy and then store the energy in the form of chemical bonds, producing oxygen from water and a reduced fuel such as hydrogen, methane, methanol, or other hydrocarbon species.

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Section: Methodsmentioning

confidence: 96%

Powering the planet: Chemical challenges in solar energy utilization

Lewis

Nocera

2006

Proc. Natl. Acad. Sci. U.S.A.

7,582

5,540

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“…A number of applications can be envisioned for these catalysts including use in alkane metathesis. [11] Experimental Section…”

Section: Discussionmentioning

confidence: 99%

“…Cyclooctane (COA), 3,3'-dimethyl-1-butene (TBE), p-xylene and mesitylene were purchased from Aldrich, dried with LiAlH 4 or Na/K, and vacuum transferred into sealed flasks. Complexes 1a, 1b, 1c, 3, [11] and [IrA C H T U N G T R E N N U N G (COD)Cl] 2 [29] were synthesized as previously reported. …”

Section: General Considerationsmentioning

confidence: 99%

“…In particular, our groups desired such catalysts to combine with heterogeneous olefin metathesis catalysts to generate a fully heterogeneous catalyst system for alkane metathesis. [11] In this paper we report the results of three strategies for preparing supported iridium pincer complexes: (i) covalent attachment of an iridium complex containing a phenoxide functionality to a Merrifield resin through an S N 2 reaction with the chlorobenzyl moieties; (ii) covalent bonding to silica of iridium pincer complexes containing a pendant alkoxysilane group; (iii) adsorption of Ir pincer complexes (particularly those containing basic functional groups) on gAl 2 O 3 through a Lewis acid/Lewis base interaction. The Merrifield resin-supported iridium POCOP catalyst was found to have low transfer-dehydrogenation activity.…”

Section: Introductionmentioning

confidence: 97%

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Highly Active and Recyclable Heterogeneous Iridium Pincer Catalysts for Transfer Dehydrogenation of Alkanes

et al. 2009

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Pincer-ligated iridium complexes have proven to be highly effective catalysts for the dehydrogenation and transfer-dehydrogenation of al-A C H T U N G T R E N N U N G kanes. Immobilization onto a solid support offers significant potential advantages in the application of such catalysts particularly with respect to catalyst separation and recycling. We describe three approaches toward such immobilization: (i) covalent attachment to a Merrifield resin, (ii) covalent bonding to silica via a pendant alkoxysilane group, and (iii) adsorption on g-alumina (g-Al 2 O 3 ), through basic functional groups on the para-position of the pincer ligand. The simplest of these approaches, adsorption on g-Al 2 O 3 , is also found to be the most effective, yielding catalysts that are robust, recyclable, and comparable to or even more active than the corresponding species in solution. Spectroscopic evidence (NMR, IR) and studies of catalytic activity support the hypothesis that binding occurs at the para-substituent and that this has only a relatively subtle and indirect influence on catalytic behavior.

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“…In the past decade, useful processes have been developed that employ alkane activation via oxidative addition; significant examples include alkane dehydrogenation (1)(2)(3)(4), alkane and arene borylation (5)(6)(7)(8)(9), and alkane metathesis (10). In all of these developments, selectivity in activation has been a critical issue, and rhodium and iridium transition metal complexes have been found to show a strong preference for the activation of the methyl C-H bonds in alkanes, despite the presence of weaker methylene C-H bonds.…”

mentioning

confidence: 99%