431-47-0Relevant articles and documents
Rosall,Robertson
, p. 869,870-872 (1975)
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.
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).
REACTION OF DIMETHYL SULFITE WITH DIMETHYLAMINOMETHYL DERIVATIVES
Baires, S. V.,Ivanov, V. B.,Ivanov, B. E.,Krokhina, S. S.,Efremov, Yu. Ya.,Korshunov, R. L.
, p. 203 - 206 (1986)
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Low-Temperature, Palladium(II)-Catalyzed, Solution-Phase Oxidation of Methane to a Methanol Derivative
Kao, Lien-Chung,Hutson, Alan C.,Sen, Ayusman
, p. 700 - 701 (1991)
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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.
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.
Methods for producing a methanol precursor, methanol, and a methyl ester from methane in high purities
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Page/Page column 10, (2021/06/02)
A method for producing a methanol precursor, methyl trifluoroacetate, having high-purity includes the steps of (a) preparing methyl bisulfate by mixing a catalyst with an acid solution comprising a sulfur-containing acid to provide a first mixture and supplying methane gas to the first mixture to prepare the methyl bisulfate; and (b) preparing methyl trifluoroacetate (CF3CO2CH3) by adding trifluoroacetic acid (CF3CO2H) to the first mixture including the methyl bisulfate to provide a second mixture and distilling the second mixture under heating to prepare, separate and purify the methyl trifluoroacetate (CF3CO2CH3). Methanol may be produced by adding water to the methyl trifluoroacetate (CF3CO2CH3). A methyl ester represented by Formula 2 below may be produced by adding a carboxylic acid represented by Formula 1 below to the methyl trifluoroacetate (CF3CO2CH3): R1CO2H??(1),where R1 is selected from C1-C10 alkyl groups, R1CO2CH3??(2),where R1 is as defined in Formula 1.
Electrocatalytic Oxyesterification of Hydrocarbons by Tetravalent Lead
Haviv, Eynat,Herman, Adi,Khenkin, Alexander M.,Neumann, Ronny
, p. 10494 - 10501 (2021/08/31)
The selective catalytic oxidative monofunctionalization of gaseous alkanes found in natural gas and commodity chemicals such as benzene and cyclohexane is an important objective in the field of carbon-hydrogen bond activation. Past research has demonstrated the possibility of stoichiometric oxyesterification of such substrates using lead(IV) trifluoroacetate (PbIV(TFA)4) as oxidant, which is driven by the high 2-electron redox potential of lead(IV). However, this redox potential then precludes reoxidation of lead(II) by a convenient oxidant such as O2, nullifying an effective catalytic cycle. In order to utilize renewable energy resources as alternatives to high-temperature thermocatalysis, we demonstrate the room-temperature electrocatalytic oxyesterification of alkanes and benzene with PbIV(TFA)4 as catalysts. At 1.67 V versus SHE, alkanes and benzene yielded the corresponding trifluoroacetate esters at room temperature; typically, good yields and high faradaic efficiencies were observed. High intrinsic turnover frequencies were obtained, for example, of >1000 min-1 for the oxyesterification of ethane at 30 bar. An analysis of the possible mechanistic pathways based on previously investigated stochiometric reactions, cyclic voltammetry measurements, kinetic isotope effects, and model compounds led to the conclusion that catalysis involves lead-mediated proton-coupled electron transfer of alkanes at and to the anode, followed by reductive elimination through an SN2 reaction to yield the alkyl-TFA products. Similarly, lead-mediated electron transfer from benzene at and to the anode leads to phenyl-TFA. Cyclic voltammetry also shows the viability of in situ reoxidation of Pb(II) species. The synthesis results obtained as well as the mechanistic insight are important advances towards the realization of selective alkane and arene oxidation reactions.
