Topic
Hydrogen atom abstraction
About: Hydrogen atom abstraction is a research topic. Over the lifetime, 7059 publications have been published within this topic receiving 151781 citations.
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TL;DR: In this paper, the rate constants for reactions in which the positive ions O+, N+, Ar+, N2+, CO+, CO2+, and N2O+ abstract a hydrogen atom from H2 have been measured at 300°K in a pulsed, flowing-afterglow reaction tube.
Abstract: Rate constants for reactions in which the positive ions O+, N+, Ar+, N2+, CO+, CO2+, and N2O+ abstract a hydrogen atom from H2 have been measured at 300°K in a pulsed, flowing‐afterglow reaction tube. Several additional reactions are observed which occur as secondary reactions in these experiments.
157 citations
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TL;DR: In this article, the surface chain reaction of styrene with hydrogen-terminated Si(111), H−Si(111) initiated at isolated surface dangling bonds is reported, which suggests that the key radical chain propagation step of hydrogen atom abstraction from the silicon surface for the proposed mechanism of reaction of liquid phase terminally unsaturated organic molecules with hydrogenterminated silicon under free-radical conditions readily occurs.
Abstract: We report the surface chain reaction of styrene with hydrogen-terminated Si(111), H−Si(111) initiated at isolated surface dangling bonds. Electrons from a scanning tunneling microscope in ultrahigh vacuum are used to create surface isolated dangling bonds on H−Si(111) prepared by aqueous ammonium fluoride etch. Exposure of dangling bonds on an otherwise hydrogen terminated surface to as little as 5 langmuirs of styrene leads to the formation of compact islands containing multiple styrene adsorbates bonded to the surface through individual C−Si bonds. From this observation we conclude that these adsorbate islands are the result of a surface chain reaction of styrene with H−Si(111). This result suggests that the key radical-chain propagation step of hydrogen atom abstraction from the silicon surface for the proposed mechanism of reaction of liquid phase terminally unsaturated organic molecules with hydrogen-terminated silicon under free-radical conditions readily occurs.
156 citations
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TL;DR: Results have been interpreted to indicate that most of the hemeproteins investigated catalyze N-demethylation reactions viaalpha-carbon hydrogen atom abstraction, while the reactions catalyzed by cytochrome P-450 and chloroperoxidase proceed via alpha-carbon deprotonation.
156 citations
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TL;DR: The data indicate a mechanism of initial hydrogen-atom abstraction forming radicals that dimerize, disproportionate and are trapped by the oxidant, which appears to apply to the oxidations of toluene, ethylbenzene, cumene, indene, and cyclohexene.
Abstract: Anaerobic oxidations of 9,10-dihydroanthracene (DHA), xanthene, and fluorene by [(bpy)2(py)RuIVO]2+ in acetonitrile solution give mixtures of products including oxygenated and non-oxygenated compounds. The products include those formed by organic radical dimerization, such as 9,9‘-bixanthene, as well as by oxygen-atom transfer (e.g., xanthone). The kinetics of these reactions have been measured. The kinetic isotope effect for oxidation of DHA vs DHA-d4 gives kH/kD ≥ 35 ± 1. The data indicate a mechanism of initial hydrogen-atom abstraction forming radicals that dimerize, disproportionate and are trapped by the oxidant. This mechanism also appears to apply to the oxidations of toluene, ethylbenzene, cumene, indene, and cyclohexene. The rate constants for H-atom abstraction from these substrates correlate well with the strength of the C−H bond that is cleaved. Rate constants for abstraction from DHA and toluene also correlate with those for oxygen radicals and other oxidants. The rate constant for H-atom tr...
154 citations