431-47-0Relevant articles and documents
Direct conversion of methane to methanol over nano-[Au/SiO2] in [Bmim]Cl ionic liquid
Li,Wang,Yu,Ma,Li,Lin
, p. 150 - 154 (2011)
This article describes a green chemical process employing nano-particle gold as the catalyst and ionic liquids (IL) as solvent for the methane oxidation. The catalytic reaction was carried out in a 100 ml autoclave filled with 2 MPa of CH4 gas, together with nano-particle gold supported on SiO2 as the catalyst, [Bmim]Cl as the solvent, trifluoroacetic acid (TFA) and trifluoroacetic anhydride (TFAA) as the acidic reagents, and K 2S2O8 as the oxidant. The influence of the amounts of Au/SiO2 and the ionic liquid on the conversion of methane was investigated at reaction temperature of 90 °C. The main product is methanol, which exists as the methyl group of the methyl trifluoroacetate. In presence of 0.01 g Au/SiO2 and 1 g IL, the methane conversion is 24.9%, the selectivity of product is up to 71.5% and the yield is 17.8%. The selectivity of carbon dioxide is 1.6% and the yield is 0.6%. The selectivity of hydrogen is 0.4% and the yield is 0.1%. In the reaction system, the gold particles and IL can be recycled, which recovery is about 96.9%. The conversion of methane in the recycled system remains as high as 21.75%. The mechanism of methane to methano conversion, as well as the catalytic action of the nano-gold, was also discussed.
Protolytic Catalysis of Anilide Methanolysis. Spectator Catalysis of Leaving-Group Departure
Venkatasubban, K. S.,Schowen, Richard L.
, p. 653 - 655 (1984)
Substituted phenols serve as general-acid catalysts of leaving-group departure from the adduct of methoxide ion with m-NO2C6H4N(CH3)COCF3 in methanol at 25 deg C.Sufficiently high concentrations of general acid convert methoxide addition to the rate-limiting step, allowing determination of rate constants for methoxide addition to substrate carbonyl (ka = 300 M-1 s-1), for overall solvent-assisted leaving-group departure (ke = kake'/k-a = 5.9 M-1 s-1) and for overall general-acid-catalyzed leaving-group departure (kBH = kakBH'/k-a = 2400 +/- 1200 M-2 s-1 for five substituted phenols with pKa's from 12.7 to 14.6).Thus the Broensted α ca. 0.It is suggested that the general acid is a spectator at spontaneous expulsion of the leaving group, producing catalysis by fast subsequent trapping of CH3NAr-.The Jencks clock shows the tetrahedral intermediate to have a minimum characteristic lifetime of 1-10 ns.
An efficient partial oxidation of methane in trifluoroacetic acid using vanadium-containing heteropolyacid catalysts
Piao, Dong-Guo,Inoue, Kensuke,Shibasaki, Hiroyasu,Taniguchi, Yuki,Kitamura, Tsugio,Fujiwara, Yuzo
, p. 116 - 120 (1999)
The new catalytic system has been examined for the partial oxidation of methane in liquid phase. It was found that the vanadium containing heteropolyacids/K2S2O8/(CF3CO) 2O/CF3COOH catalyst system converts methane to methyl trifluoroacetate along with a trace amount of methyl acetate in a 95% yield based on methane. The activation energy of the reaction was estimated to be 27.9 kcal mol-1.
Direct and remarkably efficient conversion of methane into acetic acid catalyzed by amavadine and related vanadium complexes. A synthetic and a theoretical DFT mechanistic study
Kirillova, Marina V.,Kuznetsov, Maxim L.,Reis, Patricia M.,Da Silva, Jose A. L.,Frausto Da Silva, Joao J. R.,Pombeiro, Armando J. L.
, p. 10531 - 10545 (2007)
Vanadium(IV or V) complexes with N,O- or O,O-ligands, i.e., [VO{N(CH 2CH2O)3}], Ca[V(HIDPA)2] (synthetic amavadine), Ca[V(HIDA)2], or [Bu4N]2[V(HIDA) 2] [HIDPA, HIDA = basic form of 2,2′-(hydroxyimino)dipropionic or -diacetic acid, respectively], [VO(CF3SO3) 2], Ba[VO(nta)(H2O)]2 (nta = nitrilotriacetate), [VO(ada)(H2O)] (ada = N-2- acetamidoiminodiacetate), [VO(Hheida)(H2O)] (Hheida = 2-hydroxyethyliminodiacetate), [VO(bicine)] [bicine = basic form of N,N-bis(2-hydroxyethyl)glycine], and [VO(dipic)(OCH2-CH3)] (dipic = pyridine-2,6-dicarboxylate), are catalyst precursors for the efficient single-pot conversion of methane into acetic acid, in trifluoroacetic acid (TFA) under moderate conditions, using peroxodisulfate as oxidant. Effects on the yields and TONs of various factors are reported. TFA acts as a carbonylating agent and CO is an inhibitor for some systems, although for others there is an optimum CO pressure. The most effective catalysts (as amavadine) bear triethanolaminate or (hydroxyimino)dicarboxylates and lead, in a single batch, to CH3COOH yields > 50% (based on CH4) or remarkably high TONs up to 5.6 × 103. The catalyst can remain active upon multiple recycling of its solution. Carboxylation proceeds via free radical mechanisms (CH3? can be trapped by CBrCl 3), and theoretical calculations disclose a particularly favorable process involving the sequential formation of CH3?, CH3CO?, and CH3COO? which, upon H-abstraction (from TFA or CH4), yields acetic acid. The CH3COO? radical is formed by oxygenation of CH 3CO? by a peroxo-V complex via a V{η1- OOC(O)CH3} intermediate. Less favorable processes involve the oxidation of CH3CO? by the protonated (hydroperoxo) form of that peroxo-V complex or by peroxodisulfate. The calculations also indicate that (i) peroxodisulfate behaves as a source of sulfate radicals which are methane H-abstractors, as a peroxidative and oxidizing agent for vanadium, and as an oxidizing and coupling agent for CH3CO? and that (ii) TFA is involved in the formation of CH3COOH (by carbonylating CH3?, acting as an H-source to CH 3COO?, and enhancing on protonation the oxidizing power of a peroxo-VV complex) and of CF3-COOCH3 (minor product in the absence of CO).
Homogeneous Copper-Catalyzed Conversion of Methane to Methyl Trifluoroacetate in High Yield at Low Pressure
Ravi, Manoj,van Bokhoven, Jeroen A.
, p. 2383 - 2386 (2018)
The direct catalytic oxidation of methane to oxygenates, a reaction that garners significant scientific and industrial interest, is plagued by poor methane-based yields. Some of the best homogeneous catalytic systems reported to date convert methane to methyl esters using catalysts with complex organic ligands to reach high yields at relatively high temperature (>423 K) and pressure (20–70 bar). In our study, we used a simple copper compound, copper(II) oxide, to selectively convert methane to methyl trifluoroacetate at 363 K and low pressure (5 bar) resulting in yields as high as 63 % at a methane conversion of 71 %. The catalyst is easily recovered by treating the spent reaction mixture with a base, and the catalytic performance of the recovered material is highly comparable to that of the fresh catalyst. In terms of turnover, copper oxide (TON=33 for ester yield of 56 %) ranks higher than other simple metal compounds and is comparable to catalysts with NHC ligands. Thus, this work demonstrates the possibility of using a simple catalyst devoid of complex ligands to convert methane in high yields at low pressure.
Partial oxidation of methane with the catalysis of palladium(II) and molybdovanadophosphoric acid using molecular oxygen as the oxidant
Yuan, Jiongliang,Liu, Lu,Wang, Lanlan,Hao, Cunjiang
, p. 126 - 129 (2013)
With the catalysis of K2PdCl4 and H 5PMo10V2O40 in CF3COOH, methane can be oxidized into CH3COOH and CF3COOCH 3 using molecular oxygen as the oxidant at a low temperature. H 5PMo10V2O40 is a reversible oxidant that allows to retain Pd(II) in CF3COOH and thus to complete a two-step catalytic cycle of oxidation of methane by molecular oxygen; in addition, it can catalytically oxidize methane into CH3COOH and CF3COOCH3. Graphical Abstract: [Figure not available: see fulltext.]
Cobalt-catalyzed oxidation of methane to methyl trifluoroacetate by dioxygen
Strassner, Thomas,Ahrens, Sebastian,Muehlhofer, Michael,Munz, Dominik,Zeller, Alexander
, p. 3659 - 3663 (2013)
The cobalt-catalyzed oxidation of methane to methyl trifluoroacetate by molecular oxygen in trifluoroacetic acid has been studied in detail. Yields of up to 50 % based on methane were obtained. The catalytic activities were highly dependent on the anions of the cobalt salts (CoII, CoIII) under investigation. Deactivation by precipitation of the cobalt catalyst could be prevented by the addition of trifluoroacetic anhydride. The selective cobalt-catalyzed oxidation of methane to methyl trifluoroacetate by dioxygen has been studied in detail. The catalytic activities of different cobalt precatalysts were investigated, with cobalt(II) nitrate proving to be the most efficient. The effects of solvent, reaction time, temperature, and catalyst loading have been studied. Copyright
CH-activation of methane - Synthesis of an intermediate?
Meyer, Dirk,Strassner, Thomas
, p. 84 - 87 (2015)
Abstract A dimeric methyl palladium(II) biscarbene complex with a bridging μ-chloro ligand was prepared by transmetalation from 1,1'-dimethyl-3,3'-methylenediimidazolium dichloride, silver(I) oxide and chloridomethyl(cycloctadiene)palladium(II). The complex was fully characterized and shows good activity in the CH-activation of methane. The solid state structure confirms a symmetrical dimeric structure with a μ-coordinated chlorido ligand.
Heterogeneously Catalyzed Aerobic Oxidation of Methane to a Methyl Derivative
Blankenship, Andrea N.,Newton, Mark A.,Ravi, Manoj,van Bokhoven, Jeroen A.
, p. 18138 - 18143 (2021)
A promising strategy to break through the selectivity-conversion limit of direct methane conversion to achieve high yields is the protection of methanol via esterification to a more stable methyl ester. We present an aerobic methane-to-methyl-ester approach that utilizes a highly dispersed, cobalt-containing solid catalyst, along with significantly more favorable reaction conditions compared to existing homogeneously-catalyzed approaches (e.g. diluted acid, O2 oxidant, moderate temperature and pressure). The trifluoroacetic acid medium is diluted (25 wt %) with an inert fluorous co-solvent that can be recovered after the separation of the methyl trifluoroacetate via liquid–liquid extraction at ambient conditions. Silica-supported cobalt catalysts are highly active in this system, with competitive yields and turnovers in comparison to known aerobic transition metal-based catalytic systems.
Atmosphere-Pressure Methane Oxidation to Methyl Trifluoroacetate Enabled by a Porous Organic Polymer-Supported Single-Site Palladium Catalyst
Zhang, Yiwen,Zhang, Min,Han, Zhengbo,Huang, Shijun,Yuan, Daqiang,Su, Weiping
, p. 1008 - 1013 (2021)
The efficient conversion of methane into methanol at low temperature under low pressure remains a great challenge largely because of the inertness and poor solubility of methane. Herein, we report that a porous organic polymer-supported Pd catalyst, which was constructed via Friedel-Crafts type polymerization between 4,6-dichloropyrimidine and 1,3,5-triphenyl benzene and subsequent metalation, enabled the conversion of methane to methyl trifluoroacetate, a precursor to methanol, under atmosphere pressure (1 atm) at 80 °C to afford a 51% yield relative to methane with a TON of 664 over 20 h. On increasing the pressure to 30 bar, this palladium catalyst offered a TON of 1276 for a run and could be reused for at least five runs without a notable loss of activity. The characterization of this Pd catalyst revealed its good affinity for methane uptake that would increase the concentration of methane in the local space around the Pd center and the homogeneous distribution of Pd2+ on support that would protect the catalytically active metal species, shedding light on the high catalytic activity of this Pd catalyst toward methane conversion.
