Intermolecular Hydrogen Transfer in Isobutane Hydrate

Kobayashi, Naohiro; Minami, Takashi; Tani, Atsushi; Nakagoshi, Mikio; Sugahara, Takeshi; Takeya, Kei; Ohgaki, Kazunari

doi:10.3390/en5061705

Cited by 20 publications

(17 citation statements)

References 14 publications

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“…14,15 The mechanism is thought to be H-atom transfer from an alkane to an alkyl radical, and this is supported by the modeling calculations of Alavi and Ripmeester. 39 In contrast to polyatomic radicals, H atoms are thought to diffuse freely through the clathrate structure at high temperature.…”

Section: ■ Results and Discussionmentioning

confidence: 90%

Organic Free Radicals in Clathrate Hydrates Investigated by Muon Spin Spectroscopy

et al. 2014

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Very little is known about the behavior of free H atoms and small organic radicals inside clathrate hydrate structures despite the relevance of such species to combustion of hydrocarbon hydrates. Muonium is an H atom analog, essentially a light isotope of hydrogen, and can be used to probe the chemistry of H atoms and transient free radicals. We demonstrate the first application of muon spin spectroscopy to characterize radicals in clathrate hydrates. Atomic muonium was detected in hydrates of cyclopentane and tetrahydrofuran, and muoniated free radicals were detected in the hydrates of cyclopentene and 2,5-dihydrofuran, indicating rapid addition of muonium to the organic guest. Muon avoided level-crossing spectra of the radicals in hydrates are markedly different to those of the same radicals in pure organic liquids at the same temperature, and this can be explained by limited mobility of the enclathrated radicals, leading to anisotropy in the hyperfine interactions.

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Section: ■ Results and Discussionmentioning

confidence: 90%

Organic Free Radicals in Clathrate Hydrates Investigated by Muon Spin Spectroscopy

et al. 2014

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“…Free hydrogen atoms have been clearly identified by electron spin resonance (ESR) spectroscopy (Yeon et al, 2008;Shin et al 2011;Koh et al, 2012) as well as various small alkyl radicals (Takeya et al, 2004(Takeya et al, , 2005a(Takeya et al, , 2005b(Takeya et al, , 2007. Of particular relevance to the current work are studies of H atom transfer from one radical to another (Ohgaki et al, 2008;Kobayashi et al, 2012;Sugahara et al, 2012;Oshima et al 2014). One disadvantage of radiolysis is its lack of specificitya variety of transients are produced in the primary events (H, OH, e -, and others) and their secondary reactions with the clathrate guest can lead to multiple reaction products.…”

Section: Introductionmentioning

confidence: 93%

Investigation of H atom and free radical behaviour in clathrate hydrates of organic molecules

Mozafari

Chandrasena

McKenzie

et al. 2020

Radiation Physics and Chemistry

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Clathrate hydrates are icy materials composed of a lattice of water molecules containing well-defined cavities which can accommodate small guest molecules. Their large storage capacity makes clathrates attractive media for a variety of gas storage and separation applications, but there is relatively little information on the chemical stability and diffusion of guest molecules. At the fundamental level inter-cage transition energies have been calculated, but the results need to be tested with experimental data. Ideally this should involve single-atom transport, using an isotopic tracer or spin label. Muonium (Mu = µ + e-) qualifies on both counts. As a single-electron atom with the muon as nucleus it may be considered a light isotope of hydrogen. Furthermore muonium and its reaction products may be monitored by muon spin spectroscopy. In recent years we have used this method to probe H-atom and free radical behaviour in clathrate hydrates. The current work extends studies to benzene and acetone clathrate hydrates. Of note is the simultaneous detection of muonium and muoniated radicals in the same sample. This can happen when Mu is trapped in an empty cavity, remote from its reaction partner. Increase in temperature leads to transport of Mu between cages and results in encounters with reactive guest molecules. By studying the temperature dependence of Mu and radical signals, we have been able to determine the activation energy for transport of Mu between cavities.

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“…It has been discovered that clathrate hydrate can be used as a medium for trapping radical species [2][3][4][5][6][7][8]. When hydrocarbon or binary clathrate hydrates are irradiated with g-rays, free radical species are formed.…”

Section: Introductionmentioning

confidence: 99%

Reactive radical cation transfer in the cages of icy clathrate hydrates

Koh

Kang

Lee

2015

Korean J. Chem. Eng.

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Clathrate hydrates are crystalline compounds consisting of hydrogen-bonded host water frameworks that eventually structure polyhedral cages. We suggest for the first time their potential as nano-reactors in which target reactions can occur. The energetics of one-dimensional CO radical cation (CO· + ) transfers through the hexagonal faces of sI large cages are closely examined to verify the reaction concept in an icy confined space. The barrier energies for migrating a CO radical cation from the cage center to the edge of the hexagonal face are estimated to be 87 and 311 kJ/ mol according to calculations with the B3LYP 6-311+G (d, p) basis set, significantly depending on the orientation of the radical. These results indicate that the barrier energy increases sharply when the CO radical cations are oriented parallel to the cage's hexagonal face. In the parallel migration mode, the hydrogen-bonded water networks are repulsed by electron clouds of CO· + located on the same plane; thus, the repulsion forces induce a significant increase in the barrier energies. Further, we used separate basis sets of high and low levels processed by the ONIOM scheme for the effective calculation of the entire cage structure of the clathrate hydrates with guest molecules. The calculation run time was significantly shortened when the ONIOM scheme was adopted, while a difference in the barrier energy of approximately 5% was observed compared to the full-scale calculation with a high-level basis set.

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Intermolecular Hydrogen Transfer in Isobutane Hydrate

Cited by 20 publications

References 14 publications

Organic Free Radicals in Clathrate Hydrates Investigated by Muon Spin Spectroscopy

Organic Free Radicals in Clathrate Hydrates Investigated by Muon Spin Spectroscopy

Investigation of H atom and free radical behaviour in clathrate hydrates of organic molecules

Reactive radical cation transfer in the cages of icy clathrate hydrates

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