594-11-6Relevant articles and documents
Application of aerosol techniques to study the catalytic formation of methane on gasborne nickel nanoparticles
Weber,Seipenbusch,Kasper
, p. 8958 - 8963 (2001)
A well known reaction, the so-called methanation reaction over a Ni catalyst, i.e., the formation of methane from CO and hydrogen, was studied to demonstrate the possibilities of the aerosol technique. Reaction order and activation energy conformed to generally accepted values from supported Ni catalysts. The turnover rate (TOR) decreased strongly during the first 10 sec as the reaction proceeded toward a steady value. The decrease correlated with a buildup of about 0.3 monolayer equivalents of carbon on the particle surface measured by TGA and a decline in particle photoelectric activity found via measurement by aerosol photoemission spectroscopy. Order-of-magnitude changes were induced in TOR via defined changes in particle morphology induced by aerosol restructuring techniques preceeding exposure to the catalytic reaction. Aerosol catalysis has potential to develop new catalysts and could be an avenue for studying the putative relationship between combustion aerosols and the formation of dioxin.
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Skell,Starer
, p. 2971 (1960)
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Evidence for Retention of the Cyclic C3H5 Structure during Positive-ion Processes in the Gas Phase
Colosimo, Marcello,Bucci, Roberto
, p. 659 - 661 (1981)
The decomposition of gaseous cyclopropylmethylbromonium ions has yielded the cyclic hydrocarbons cyclopropane and methylcyclopropane, and methyl bromide.
Light-Promoted Transfer of an Iridium Hydride in Alkyl Ether Cleavage
Fast, Caleb D.,Schley, Nathan D.
supporting information, p. 3291 - 3297 (2021/10/12)
A catalytic, light-promoted hydrosilylative cleavage reaction of alkyl ethers is reported. Initial studies are consistent with a mechanism involving heterolytic silane activation followed by delivery of a photohydride equivalent to a silyloxonium ion generated in situ. The catalyst resting state is a mixture of Cp*Ir(ppy)H (ppy = 2-phenylpyridine-κC,N) and a related hydride-bridged dimer. Trends in selectivity in substrate reduction are consistent with nonradical mechanisms for C-O bond scission. Irradiation of Cp*Ir(ppy)H with blue light is found to increase the rate of hydride delivery to an oxonium ion in a stoichiometric test. A comparable rate enhancement is found in carbonyl hydrosilylation catalysis, which operates through a related mechanism also involving Cp*Ir(ppy)H as the resting state.
Homolytic C-S bond scission in the desulfurization of aromatic and aliphatic thiols mediated by a Mo/Co/S cluster: Mechanistic aspects relevant HDS catalysis
Curtis, M. David,Druker, Scott H.
, p. 1027 - 1036 (2007/10/03)
The kinetics of the reaction of a series of aromatic and aliphatic thiols with cluster 1 were determined. These reactions form cluster 2 and the arene or alkane corresponding to the thiol: Cp'2Mo2Co2S3(CO)4 (1) + RSH → Cp'2Mo2Co2S4(CO)2 (2) + RH + 2CO. These reactions are first order in thiol and first order in cluster 1 with appreciable negative entropies of activation. These data suggest that the rate determining step of the desulfurization reaction is the initial association of the thiol to the cluster. The more nucleophilic thiolate anions react with 1 at -40°C to form an adduct in which the thiolate anion is bound η1 to the Co atom. At -25°C, the initial adduct rearranges to a fluxional μ2, η1-bound thiolate. The fluxional process is proposed to involve a concerted 'walking' of the thiolate and a μ2-bound sulfide ligand on the surface of the cluster. Near 35°C, the thiolate-cluster adduct undergoes C-S bond homolysis to give the paramagnetic anion of cluster 1 and the phenyl or alkyl radical. The radical nature of the C-S bond cleavage was confirmed by the desulfurization of the radical clock reagents, cyclopropylmethanethiol and -thiolate anion, that form the cyclopropylmethyl radical which rearranged to the butenyl radical. The possible similarity in the C-S bond cleavage mechanism in these desulfurization reactions to those occurring in hydrodesulfurization (HDS) over Co/Mo/S catalysts is discussed.
