676-49-3Relevant academic research and scientific papers
Absoption and Reactions of Methanethiol on Clean and Modified Ni(110)
Huntley, D. R.
, p. 6156 - 6164 (1989)
The reactions of methanethiol on clean and modified Ni(110) have been studied under ultrahigh-vacuum conditions by temperature-programmed reactions (TPR), including deuterium incorporation studies.Surface bound molecular fragments were identified by X-ray photoelectron spectroscopy (XPS) and high-resolution electron energy loss spectroscopy (HREELS).The TPR data indicate that the major products of the reactions of methanethiol with clean Ni(110) surfaces are methane and hydrogen.Methane desorbs in a reaction-limited peak at 276 K, which does not shift with methanethiol exposure.Hydrogen desorption occurs in several peaks depending on the exposure.The coverage dependence of the methane yield indicates a competition between decomposition and reaction to form methane.At low coverages, decomposition is the major pathway while at higher coverages methane formation dominates.Vibrational spectroscopy (HREELS) indicates the presence of the methyl thiolate intermediate at temperatures less than 200 K.X-ray photoelectron spectroscopy and deuterium incorporation experiments confirm this assignment.A mechanism has been proposed based on hydrogenolysis of the methyl thiolate species and is consistent with all of the data.The appropriate rate equations associated with this mechanism have been solved numerically to predict the TPR data, and qualitative agreement was achieved .Methanethiol reacts with sulfur- and oxigen-modified Ni(110) surfaces to produce methane, hydrogen, and, in the case of the oxidized surfaces , water.The major effect of the modifier was to enhance the formation of methane relative to decomposition.These observations can be explained by either electronic or structural effects.
Activation of Methane Promoted by NeohexylPt(II) Complexes. Isolation of MethylPt(II) Complexes
Miyashita, Akira,Saida, Yoshiko
, p. 2263 - 2266 (1994)
trans-Pt(CH2CMe2Et)Br(PPh3)2 induced C-H bond activation of CH4 under UV p irradiation leading to trans-PtMeBr(PPh3)2, while H-D exchange reaction of CH4 with D2 or D2SO4 took place in the photochemical reaction system containing Pt(PPh3)4 and neonexyl bromide.A possible reaction mechanism involving radical process is discussed on the basis of radical-trap experiment.
H/D exchange between CH4 and CD4 catalysed by a silica supported tantalum hydride, (?SiO)2Ta-H
Lefort, Laurent,Coperet, Christophe,Taoufik, Mostafa,Thivolle-Cazat, Jean,Basset, Jean-Marie
, p. 663 - 664 (2000)
The silica supported tantalum hydride (?SiO)2Ta-H 1, catalyses the H/D exchange reaction between CH4 and CD4 at 150 °C producing the statistical distribution of all methane isotopomers.
Activation of C-H Bonds in Saturated Hydrocarbons. H-D Exchange between Methane and Benzene catalysed by a Soluble Iridium Polyhydride System
Cameron, Charles J.,Felkin, Hugh,Fillebeen-Khan, Tauqir,Forrow, Nigel J.,Guittet, Eric
, p. 801 - 802 (1986)
The soluble iridium pentahydride (i-Pr3P)2IrH5 (activated by t-Bu-CH=CH2) catalyses H-D exchange between C6D6 and CH4 under mild conditions.
Reactivity of Tricyclopentadienyl Uranium Tetrahydroaluminate
Ossola, Franco,Brianese, Nicola,Porchia, Marina,Rossetto, Gilberto,Zanella, Pierino
, p. 877 - 880 (1990)
The reactivity of (1) (cp = η5-C5H5) has been studied.With (CH3)3CNC it gives >, with pyridine , with CH3CN and , with (CH3)3CNCO, which probably inserts into
The Oxidative Coupling of Methane on Lithium Nickelate(III)
Hatano, Masaharu,Otsuka, Kiyoshi
, p. 199 - 206 (1989)
Kinetic studies and isotopic exchange measurements (CH4-CD4 and 16O2-18O2) of the oxidative coupling of methane over stoichiometric LiNiO2 indicate a redox mechanism involving lattice oxygen atoms.The formation of C2 products is second-order in methane, both in the presence and absence of gaseous oxygen.Methane is dissociatively adsorbed on Ni3+-O2- sites, and the rate-determining step is the coupling of adsorbed CH3.Reduction of the catalyst by methane forms NiO, over which deep oxidation occurs.Adsorbed oxygen or gaseous oxygen is responsible for the deep oxidation.
Interaction of gaseous D atoms with alkyl halides adsorbed on Pt(111), H/Pt(111), and C/Pt(111) surfaces: Hot-atom and Eley-Rideal reactions. I. Methyl bromide
Wehner,Kueppers
, p. 3209 - 3217 (1999)
The interaction of gaseous D atoms with methyl bromide molecules adsorbed on Pt(111), hydrogen saturated Pt(111), and graphite monolayer covered Pt(111) surfaces was studied in order to elucidate the reaction mechanisms. The reaction kinetics at 85 K surface temperature were measured as a function of the methyl bromide precoverage by monitoring reaction products simultaneously with D atom exposure. On all substrates incoming atoms abstract the methyl group from adsorbed CH3Br via gaseous CH3D formation. In the monolayer regime of CH3Br/Pt(111) pure hot-atom phenomenology was observed in the rates. At multilayer targets the fluence dependence of the kinetics gets Eley-Rideal-like. With coadsorbed H present, the reaction of D with adsorbed methyl bromide revealed in addition to CH3D a CH4 product. This and simultaneous abstraction of adsorbed H via gaseous HD and H2 products clearly demonstrates that hot-atom reactions occur. At CH3Br adsorbed on a graphite monolayer on Pt(111) the abstraction kinetics of methyl was found to agree with the operation of an Eley-Rideal mechanism. These observations are in line with the expectation that hot-atoms do not exist on a CTPt(111) surface but on Pt(111) and H/Pt(111) surfaces. The methyl abstraction cross-sections in the monolayer regime of methyl bromide were determined as about 0.25 A2, irrespective of the nature of the substrate. This value is in accordance with direct, Eley-Rideal or hot-atom reactions.
Experimental and RRKM Modeling Study of the CH3+H and CH3+D Reactions
Brouard, Mark,Macpherson, Martyn T.,Pilling, Michael J.
, p. 4047 - 4059 (1989)
Rate coefficients for the reactions CH3+H and CH3+D are presented over the temperature ranges 300* to generate CH2D+H is much faster than that to regenerate CH3+D under all conditions studied; in consequence the measured rate coefficient corresponds, in effect, to the high-pressure limit, kinfinite1(D).Fits to the CH3+H falloff data show that the high-pressure limit, kinfinite1(H), at 300 K exceeds that predicted from kinfinite1(D) by at least a factor of 2.This conclusion is confirmed by detailed master equation calculations that incorporate microcanonical dissociation rate coefficients calculated on the basis of a variational RRKM procedure.Parameters are provided that give a satisfactory representation of the CH3+H rate data, over the experimental pressure and tempereture ranges, with a temperature-independence value of kinfinite1(H) of 4.7E-10 cm3 molecule-1s-1 with uncertainties of Δlog kinfinite1(H) ca. +0.2 to -0.1 at 300 K rising to ca. +/-0.4 at 600 K.
On the Mechanism of Base-catalysed Alkane-forming Reactions of Simple Alkylcobaloximes
Brown, Kenneth L.
, p. 598 - 599 (1981)
From the time dependence of the formation of monodeuterioalkanes in D2O, and related isotopic labelling experiments, the base-catalysed alkane-forming reactions of ethyl- and methyl-(aquo)cobaloximes have been found to occur via different mechanisms.
Platinum catalyzed c-h activation and the effect of metal-support interactions
Sattler, Aaron,Paccagnini, Michele,Lanci, Michael P.,Miseo, Sabato,Kliewer, Chris E.
, p. 710 - 720 (2020/01/02)
Catalytic C-H bond activation of methane and ethane on a series of silica supported platinum catalysts (Pt/SiO2) was studied by using hydrogen/deuterium (H/D) exchange. Kinetic experiments demonstrate that under the reaction conditions studied, the rate of C-H bond activation shows approximate first order dependence in alkane and inverse first order dependence in D2. The rate of C-H activation is affected by the presence of sodium on the silica support, where sodium-free supports have the fastest rates of C-H activation, as assessed by H/D exchange. CO adsorption and FTIR studies indicate that the Pt particles on the sodium-free support are more electron-deficient, having the most blue-shifted linear CO stretch, while sodium-containing supports are more electron-donating, having the most red-shifted linear CO stretch. It is proposed, based on the results described in this article and previous work in the literature, that more electron-donating supports cause the Pt particles to be more electron-rich and to adsorb D? (or H*) more strongly, thereby stabilizing the ground state and resting state of the catalyst, resulting in a decreased rate of C-H activation.
