Search results for " Methane"
showing 10 items of 146 documents
Modular Access to 9,9-Spirobifluorenes by Oxidative Coupling Using Molybdenum Pentachloride
2013
The strong oxidizing agent molybdenum pentachloride was used for an efficient direct C–C bond formation of 9,9-diarylfluorenes to the corresponding 9,9-spirobifluorenes. Thus, a versatile method that is compatible with labile groups, such as iodo moieties, was established. By this approach important building blocks for light emitting polymers were synthesized in high yields.
Gold Redox Catalytic Cycles for the Oxidative Coupling of Alkynes
2011
[EN] Au(I)/Au(III) catalytic cycles are catalytically competent to perform the oxidative coupling of alkynes in the homogeneous phase at room temperature and without any protecting atmosphere. Selectfluor as oxidant, wet acetonitrile as solvent, and sodium carbonate as base are the reagents of choice. Both aromatic and alkyl alkynes can be coupled, and mechanistic studies reveal that at least two gold species having different oxidation states are implicated in the key step of the coupling.
Support effect on the catalytic performance of Au/Co3O4–CeO2 catalysts for CO and CH4 oxidation
2008
Gold-based catalysts supported on Co3O4, on CeO2 and on mixed Co3O4-CeO2 oxides were prepared by co-precipitation. They were tested in the catalytic oxidation of CO and CH4, in separate tests, and their activities were compared with that of the bare oxides. Tests of CH4 oxidation were performed in two consecutive runs in order to evaluate the catalysts stability. The effect of SO2 in the reactant mixture was investigated. The fresh and spent catalysts were analsed by XRD, BET, TPR and XPS techniques. Among the fresh catalysts, Au supported on CeO2 was the most active in CO oxidation whereas Au supported on Co3O4 was the most active for methane total oxidation. Synergy between the two oxides…
Iodine oxidative coupling of diene and triene-diolates of unsaturated carboxylic acids.
1991
Abstract Oxidative Coupling of the dianions of unsaturated carboxylic acids 1 , and 4 with iodine, which provides a convenient and facile preparation of γ,γ and e,e-dicarboxylic acids 2 and 5, apparently occurs through SET substitution of intermediate iodo-carboxylates.
ChemInform Abstract: Iodine Oxidative Coupling of Diene- and Triene-Diolates of Unsaturated Carboxylic Acids.
2010
Abstract Oxidative Coupling of the dianions of unsaturated carboxylic acids 1 , and 4 with iodine, which provides a convenient and facile preparation of γ,γ and e,e-dicarboxylic acids 2 and 5, apparently occurs through SET substitution of intermediate iodo-carboxylates.
Recycling and fluxes of carbon gases in a stratified boreal lake following experimental carbon addition
2014
Partly anoxic stratified humic lakes are important sources of methane (CH4) and carbon dioxide (CO2) to the atmosphere. We followed the fate of CH4 and CO2 in a small boreal stratified lake, Alinen Mustajärvi, during 2007–2009. In 2008 and 2009 the lake received additions of dissolved organic carbon (DOC) with stable carbon isotope ratio (δ13C) around 16‰ higher than that of local allochthonous DOC. Carbon transformations in the water column were studied by measurements of δ13C of CH4 and of the dissolved inorganic carbon (DIC). Furthermore, CH4 and CO2 production, consumption and emissions were estimated. Methane oxidation was estimated by a diffusion gradient method. The amount, lo…
ChemInform Abstract: Modular Access to 9,9-Spirobifluorenes by Oxidative Coupling Using Molybdenum Pentachloride.
2013
The reactions of diarylfluorenes and substrates (III) or (V) result in formation of spirobifluorenes and fluorene derivatives.
Rhodium catalyzed oxidative coupling of salicylaldehydes with diazabicyclic olefins: a one pot strategy involving aldehyde C–H cleavage and π-allyl c…
2013
An efficient one pot strategy for the synthesis of cyclopentene fused chromanone derivatives through the direct oxidative coupling of salicylaldehydes with bicyclic olefins in the presence of a rhodium-copper catalyst system is described. This is the first report on the ring opening-ring closing of bicyclic hydrazines via metal catalyzed oxidative coupling reaction.
Modular Approach to 9-Monosubstituted Fluorene Derivatives Using Mo(V) Reagents.
2016
Oxidative coupling using molybdenum(V) reagents provides fast access to highly functionalized 9-monosubstituted fluorenes. This synthetic approach is highly modular, is high yielding, and tolerates a variety of labile moieties, e.g. amides or iodo groups. The established protocol leads to promising precursors for pharmacologically important analogues of melatonin.
Electrochemical monitoring of the oxidative coupling of alkynes catalyzed by triphenylphosphine gold complexes
2012
Electrochemical monitoring of the oxidative coupling of alkynes in the homogeneous phase through catalytic cycles involving triphenylphosphine gold complexes and selectfluor as oxidant reveals that at least two gold species in +3 and +1 oxidation states are implicated. Electrochemically driven homocoupling of terminal alkynes using molecular oxygen as the oxidant can be performed using such catalysts. Keywords: Gold catalysis, Oxidative coupling of alkynes, Oxygen, Voltammetry