- Direct conversion of methane to methanol over nano-[Au/SiO2] in [Bmim]Cl ionic liquid
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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.
- Li,Wang,Yu,Ma,Li,Lin
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- Protolytic Catalysis of Anilide Methanolysis. Spectator Catalysis of Leaving-Group Departure
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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.
- Venkatasubban, K. S.,Schowen, Richard L.
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- An efficient partial oxidation of methane in trifluoroacetic acid using vanadium-containing heteropolyacid catalysts
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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.
- Piao, Dong-Guo,Inoue, Kensuke,Shibasaki, Hiroyasu,Taniguchi, Yuki,Kitamura, Tsugio,Fujiwara, Yuzo
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- 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
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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).
- Kirillova, Marina V.,Kuznetsov, Maxim L.,Reis, Patricia M.,Da Silva, Jose A. L.,Frausto Da Silva, Joao J. R.,Pombeiro, Armando J. L.
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- Homogeneous Copper-Catalyzed Conversion of Methane to Methyl Trifluoroacetate in High Yield at Low Pressure
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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.
- Ravi, Manoj,van Bokhoven, Jeroen A.
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- Partial oxidation of methane with the catalysis of palladium(II) and molybdovanadophosphoric acid using molecular oxygen as the oxidant
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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.]
- Yuan, Jiongliang,Liu, Lu,Wang, Lanlan,Hao, Cunjiang
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- Cobalt-catalyzed oxidation of methane to methyl trifluoroacetate by dioxygen
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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
- Strassner, Thomas,Ahrens, Sebastian,Muehlhofer, Michael,Munz, Dominik,Zeller, Alexander
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- CH-activation of methane - Synthesis of an intermediate?
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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.
- Meyer, Dirk,Strassner, Thomas
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- Heterogeneously Catalyzed Aerobic Oxidation of Methane to a Methyl Derivative
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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.
- Blankenship, Andrea N.,Newton, Mark A.,Ravi, Manoj,van Bokhoven, Jeroen A.
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- Atmosphere-Pressure Methane Oxidation to Methyl Trifluoroacetate Enabled by a Porous Organic Polymer-Supported Single-Site Palladium Catalyst
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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.
- Zhang, Yiwen,Zhang, Min,Han, Zhengbo,Huang, Shijun,Yuan, Daqiang,Su, Weiping
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- Methods for producing a methanol precursor, methanol, and a methyl ester from methane in high purities
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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.
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Page/Page column 10
(2021/06/02)
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- Aerobic Partial Oxidation of Alkanes Using Photodriven Iron Catalysis
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Photodriven oxidations of alkanes in trifluoroacetic acid using commercial and synthesized Fe(III) sources as catalyst precursors and dioxygen (O2) as the terminal oxidant are reported. The reactions produce alkyl esters and occur at ambient temperature in the presence of air, and catalytic turnover is observed for the oxidation of methane in a pure O2 atmosphere. Under optimized conditions, approximately 17% conversion of methane to methyl trifluoroacetate at more than 50% selectivity is observed. It is demonstrated that methyl trifluoroacetate is stable under catalytic conditions, and thus overoxidized products are not formed through secondary oxidation of methyl trifluoroacetate.
- Cao, Yuan,Coutard, Nathan,Goldberg, Jonathan M.,Groves, John T.,Gunnoe, T. Brent,Jeffrey, Philip D.,Jia, Xiaofan,Valle, Henry U.
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supporting information
(2022/01/11)
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- Electrocatalytic Oxyesterification of Hydrocarbons by Tetravalent Lead
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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.
- Haviv, Eynat,Herman, Adi,Khenkin, Alexander M.,Neumann, Ronny
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p. 10494 - 10501
(2021/08/31)
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- Functionalization of RhIII-Me Bonds: Use of capping Arene Ligands to Facilitate Me-X Reductive Elimination
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We show how to improve the yield of MeX from CH4 activation catalysts from 12% to 90% through the use of capping arene ligands. Four (FP)RhIII(Me)(TFA)2 {FP = capping arene ligands, including 8,8′-(1,2-phenylene)diquinoline (6-FP), 8,8′-(1,2-naphthalene)diquinoline (6-NPFP), 1,2-bis(N-7-azaindolyl)benzene (5-FP), and 1,2-bis(N-7-azaindolyl)naphthalene (5-NPFP)} complexes. These complexes and (dpe)RhIII(Me)(TFA)2 (dpe = 1,2-di-2-pyridylethane) were synthesized and tested for their performance in reductive elimination of MeX (X = TFA or halide). The FP ligands were used with the goal of blocking a coordination site to destabilize the RhIII complexes and facilitate MeX reductive elimination. On the basis of single-crystal X-ray diffraction studies, the 6-FP and 6-NPFP ligated Rh complexes have Rh-arene distances shorter than those of the 5-FP and 5-NPFP Rh complexes; thus, it is expected that the Rh-arene interactions are weaker for the 5-FP complexes than for the 6-FP complexes. Consistent with our hypothesis, the 5-FP and 5-NPFP RhIII complexes demonstrate improved performance (from 12% to ～60% yield) in the reductive elimination of MeX. The reductive elimination of MeX from (FP)RhIII(Me)(TFA)2 can be further improved by the use of chemical oxidants. For example, the addition of 2 equiv of AgOTf leads to 87(2)% yield of MeTFA and can be achieved in CD3CN at 90 °C using (5-FP)Rh(Me)(TFA)2.
- Gu, Shunyan,Chen, Junqi,Musgrave, Charles B.,Gehman, Zo? M.,Habgood, Laurel G.,Jia, Xiaofan,Dickie, Diane A.,Goddard, William A.,Gunnoe, T. Brent
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p. 1889 - 1906
(2021/05/29)
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- Chemoselective Cleavage of Si-C(sp3) Bonds in Unactivated Tetraalkylsilanes Using Iodine Tris(trifluoroacetate)
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Organosilanes are synthetically useful reagents and precursors in organic chemistry. However, the typical inertness of unactivated Si-C(sp3) bonds under conventional reaction conditions has hampered the application of simple tetraalkylsilanes in organic synthesis. Herein we report the chemoselective cleavage of Si-C(sp3) bonds of unactivated tetraalkylsilanes using iodine tris(trifluoroacetate). The reaction proceeds smoothly under mild conditions (-50 °C to room temperature) and tolerates various polar functional groups, thus enabling subsequent Tamao-Fleming oxidation to provide the corresponding alcohols. NMR experiments and density functional theory calculations on the reaction indicate that the transfer of alkyl groups from Si to the I(III) center and the formation of the Si-O bond proceed concertedly to afford an alkyl-λ3-iodane and silyl trifluoroacetate. The developed method enables the use of unactivated tetraalkylsilanes as highly stable synthetic precursors.
- Matsuoka, Keitaro,Komami, Narumi,Kojima, Masahiro,Mita, Tsuyoshi,Suzuki, Kimichi,Maeda, Satoshi,Yoshino, Tatsuhiko,Matsunaga, Shigeki
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supporting information
p. 103 - 108
(2021/01/13)
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- Catalysts for methane activation and manufacturing method of methylestare using the same
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The invention relates to catalysts and processes for the oxidation of methane to produce methyl esters. The methane activating catalyst according to the present invention shows excellent catalytic activity under conditions of low temperature and weak acid, and has little deterioration in catalyst performance even in repeated use, thereby being advantageous for production of methanol from methane.
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Paragraph 0167-0200
(2021/08/17)
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- KF-Promoted copper-catalyzed highly efficient and selective oxidation of methane and other alkanes with a dramatic additive effect
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Highly efficient oxidation of methane to methyl trifluoroacetate mediated by CuCl/KF/K2S2O8in trifluoroacetic acid (TFA) and trifluoroacetic anhydride (TFAA) is described. The additive effect has been systematically evaluated and potassium fluoride (KF) was identified as the most effective promoter among the salts screened. KF is conjectured to exhibit the salt effect to promote the [SO4˙]?radical to escape the solvent cage based on control experiments. Cyclohexane and adamantane could also be efficiently oxidized into benzene or corresponding trifluoroacetates.
- Chen, Wei,Chen, Xiaoyan,Fan, Wu,Li, Suhua,Liu, Luyao
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p. 4962 - 4968
(2021/07/26)
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- SN2 and E2 Branching of Main-Group-Metal Alkyl Intermediates in Alkane CH Oxidation: Mechanistic Investigation Using Isotopically Labeled Main-Group-Metal Alkyls
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The main-group-metal alkyl compounds trialkyltin and dialkylthallium have been utilized to investigate the mechanism of functionalization of monoalkyl thallium and lead species, proposed to be putative intermediates in alkane (RH) functionalization, formed via CH activation of alkanes (methane, ethane, and propane) using electrophilic Tl(III) and Pb(IV) in trifluoroacetic acid (HTFA). Two different organometallic transalkylation methods were used to generate the putative intermediates in situ. The results herein strongly support a mechanism of CH activation to generate a main-group-metal alkyl intermediate which undergoes reductive functionalization to generate the products, R-TFA, and the reduced metal salt. In the case of ethane there are two products, ethyl trifluoroacetate (EtTFA) and 1,2-bis(trifluoroacetoxy)ethylene glycol (EG(TFA)2), observed in the reaction mixture that are proposed to form in parallel from a common intermediate, EtTl(TFA)2. The alkyl transfer studies herein strongly support the simultaneous formation of both species from this intermediate. Furthermore, studies conducted using regiospecifically isotopically labeled diethylthallium salts strongly support an SN2 functionalization from EtTl(TFA)2 to give EtTFA (and reduced Tl(TFA)) and an E2 elimination (also from EtTl(TFA)2) to generate ethylene, which instantly reacts with an additional 1 equiv of Tl(TFA)3 to generate EG(TFA)2.
- Ess, Daniel H.,Gunsalus, Niles Jensen,Hashiguchi, Brian G.,Konnick, Michael M.,Koppaka, Anjaneyulu,Park, Sae Hume,Periana, Roy A.
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p. 1907 - 1916
(2020/06/08)
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- Optimization and sustainability assessment of a continuous flow Ru-catalyzed ester hydrogenation for an important precursor of a β2-adrenergic receptor agonist
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The development of a ruthenium-catalyzed continuous flow ester hydrogenation using hydrogen (H2) gas is reported. The reaction was utilized for the reduction of an important precursor in the synthesis of abediterol, a β2-adrenoceptor agonist that has undergone phase IIa clinical trials for the treatment of asthma and chronic obstructive pulmonary disorder. The reaction was investigated within a batch autoclave by using a design of experiments (DoE) approach to identify important parameter effects. The optimized flow process was successfully operated over 6 h with inline benchtop19F NMR spectroscopy for reaction monitoring. The protocol is shown to be high yielding (98% yield, 3.7 g h?1) with very low catalyst loading (0.065 mol%). The environmental impact of the Ru-catalyzed hydrogenation was assessed and compared to an existing stoichiometric lithium aluminum hydride (LAH) reduction and sodium borohydride (NaBH4) reduction. The process mass intensity (PMI) for the Ru-catalyzed hydrogenation (14) compared favorably to a LAH reduction (52) and NaBH4reduction (133).
- García-Lacuna, Jorge,Hone, Christopher A.,Kappe, C. Oliver,Leslie, Kevin,Munday, Rachel,O'Kearney-McMullan, Anne,Prieschl, Michael
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supporting information
p. 5762 - 5770
(2020/09/21)
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- Catalytic conversion of ketones to esters: Via C(O)-C bond cleavage under transition-metal free conditions
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The catalytic conversion of ketones to esters via C(O)-C bond cleavage under transition-metal free conditions is reported. This catalytic process proceeds under solvent-free conditions and offers an easy operational procedure, broad substrate scope with excellent selectivity, and reaction scalability. This journal is
- Subaramanian, Murugan,Ramar, Palmurukan M.,Rana, Jagannath,Gupta, Virendra Kumar,Balaraman, Ekambaram
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supporting information
p. 8143 - 8146
(2020/09/09)
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- Selective Photo-Oxygenation of Light Alkanes Using Iodine Oxides and Chloride
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Partial oxidation of light alkanes to generate alkyl esters has been achieved under photochemical conditions using mixtures of iodine oxides and chloride salts in trifluoroacetic acid (HTFA). The reactions are catalytic in chloride and are successful using compact fluorescent light, but higher yields are obtained using a mercury lamp. In this photo-initiated oxyesterification process, the robust alkyl ester products are resistant to over-oxidation, and under optimized conditions yields for alkyl ester production of ～50 % based on methane, ～60 % based on ethane (with a total functionalized yield of EtX (X=TFA or Cl) of 80 %) and ～30 % based on propane have been demonstrated. The reaction also proceeds in aqueous HTFA and dichloroacetic acid with lower yields. Mechanistic studies indicate that the process likely operates by a chlorine hydrogen atom abstraction pathway wherein alkyl radicals are generated, trapped by iodine, and converted to alkyl trifluoroacetates in situ.
- Liebov, Nichole S.,Goldberg, Jonathan M.,Boaz, Nicholas C.,Coutard, Nathan,Kalman, Steven E.,Zhuang, Thompson,Groves, John T.,Gunnoe, T. Brent
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p. 5045 - 5054
(2019/10/28)
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- Production Method for 1,2,2,2-Tetrafluoroethyl Difluoromethyl Ether (Desflurane)
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Fluoral is obtained by gas-phase fluorination of chloral in the presence of a catalyst and then reacted with trimethyl orthoformate, thereby readily forming 1,2,2,2-tetrafluoroethyl methyl ether as an intermediate for production of desflurane. 1,2,2,2-Tetrafluoroethyl difluoromethyl ether (desflurane) is produced with high yield from the thus-formed 1,2,2,2-tetrafluoroethyl methyl ether by chlorination and fluorination. This method enables efficient industrial-scale production of desflurane useful as an inhalation anesthetic
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Paragraph 0134-0135
(2019/11/22)
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- Mechanism of Hydrocarbon Functionalization by an Iodate/Chloride System: The Role of Ester Protection
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Mixtures of chloride and iodate salts for light alkane oxidation achieve >20% yield of methyl trifluoroacetate (TFA) from methane with >85% selectivity. The mechanism of this C-H oxygenation has been probed by examining adamantane as a model substrate. These recent results lend support to the involvement of free radicals. Comparative studies between radical chlorination and iodate/chloride functionalization of adamantane afford statistically identical 3°:2° selectivities (～5.2:1) and kinetic isotope effects for C-H/C-D functionalization (kH/kD = 1.6(3), 1.52(3)). Alkane functionalization by iodate/chloride in HTFA is proposed to occur through H-atom abstraction by free radical species including Cl? to give alkyl radicals. Iodine, which forms by in situ reduction of iodate, traps alkyl radicals as alkyl iodides that are subsequently converted to alkyl esters in HTFA solvent. Importantly, the alkyl ester products (RTFA) are quite stable to further oxidation under the oxidizing conditions due to the protecting nature of the ester moiety.
- Schwartz, Nichole A.,Boaz, Nicholas C.,Kalman, Steven E.,Zhuang, Thompson,Goldberg, Jonathan M.,Fu, Ross,Nielsen, Robert J.,Goddard, William A.,Groves, John T.,Gunnoe, T. Brent
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p. 3138 - 3149
(2018/04/14)
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- A process for the preparation of suitable ester
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The invention relates to a preparation method of trifluoroacetate. The preparation method is characterized by comprising the following steps: (1) after uniformly mixing potassium fluoride with alcohol, adding trifluoroacetyl fluoride for reaction; (2) filtering a reaction mixture to remove potassium fluoride-potassium bifluoride solids; and (3) rectifying to obtain the trifluoroacetate. The method provided by the invention simplifies the preparation process of the trifluoroacetate, no waste acids and catalysts are generated in the reaction process, and by-products of reaction can be recycled, so that the environmental protection problem in synthesis of the trifluoroacetate is solved.
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Paragraph 0025-0026
(2020/02/08)
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- PREPARATION OF COMPOUNDS FROM LEVULINIC ACID
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The present invention provides a method of making carboxylic acids from levulinic acid, such as succinic acid and 3-hydroxypropanoic acid, by reacting levulinic acid with an oxidant such as hydrogen peroxide under acidic or basic conditions.
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Paragraph 0062
(2016/08/23)
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- Partial oxidation of light alkanes by periodate and chloride salts
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The efficient and selective partial oxidation of light alkanes using potassium periodate and potassium chloride is reported. Yields of methane functionalization in trifluoroacetic acid reach >40% with high selectivity for methyl trifluoroacetate. Periodat
- Kalman, Steven E.,Munz, Dominik,Fortman, George C.,Boaz, Nicholas C.,Groves, John T.,Gunnoe, T. Brent
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supporting information
p. 5294 - 5298
(2015/03/30)
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- Efficient, metal-free production of succinic acid by oxidation of biomass-derived levulinic acid with hydrogen peroxide
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A practical, scalable, metal-free synthesis of succinic acid from the biomass-derived platform chemical levulinic acid is described. Treatment of levulinic acid with the inexpensive, simple oxidant hydrogen peroxide under the catalytic action of trifluoroacetic acid gives succinic acid in high yield and enables facile product isolation by simple distillation of the volatile catalyst and byproducts.
- Dutta, Saikat,Wu, Linglin,Mascal, Mark
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supporting information
p. 2335 - 2338
(2015/04/22)
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- Atmospheric Chemistry of (CF3)2CHOCH3, (CF3)2CHOCHO, and CF3C(O)OCH3
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Smog chambers with in situ FTIR detection were used to measure rate coefficients in 700 Torr of air and 296 ± 2 K of: k(Cl+(CF3)2CHOCH3) = (5.41 ± 1.63) × 10-12, k(Cl+(CF3)2CHOCHO) = (9.44 ± 1.81) × 10-15, k(Cl+CF3C(O)OCH3) = (6.28 ± 0.98) × 10-14, k(OH+(CF3)2CHOCH3) = (1.86 ± 0.41) × 10-13, and k(OH+(CF3)2CHOCHO) = (2.08 ± 0.63) × 10-14 cm3 molecule-1 s-1. The Cl atom initiated oxidation of (CF3)2CHOCH3 gives (CF3)2CHOCHO in a yield indistinguishable from 100%. The OH radical initiated oxidation of (CF3)2CHOCH3 gives the following products (molar yields): (CF3)2CHOCHO (76 ± 8)%, CF3C(O)OCH3 (16 ± 2)%, CF3C(O)CF3 (4 ± 1)%, and C(O)F2 (45 ± 5)%. The primary oxidation product (CF3)2CHOCHO reacts with Cl atoms to give secondary products (molar yields): CF3C(O)CF3 (67 ± 7)%, CF3C(O)OCHO (28 ± 3)%, and C(O)F2 (118 ± 12)%. CF3C(O)OCH3 reacts with Cl atoms to give: CF3C(O)OCHO (80 ± 8)% and C(O)F2 (6 ± 1)%. Atmospheric lifetimes of (CF3)2CHOCH3, (CF3)2CHOCHO, and CF3C(O)OCH3 were estimated to be 62 days, 1.5 years, and 220 days, respectively. The 100-year global warming potentials (GWPs) for (CF3)2CHOCH3, (CF3)2CHOCHO, and CF3C(O)OCH3 are estimated to be 6, 121, and 46, respectively. A comprehensive description of the atmospheric fate of (CF3)2CHOCH3 is presented.
- ?sterstr?m, Freja From,Wallington, Timothy J.,Sulbaek Andersen, Mads P.,Nielsen, Ole John
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p. 10540 - 10552
(2015/11/09)
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- Selective monooxidation of light alkanes using chloride and iodate
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We describe an efficient system for the direct partial oxidation of methane, ethane, and propane using iodate salts with catalytic amounts of chloride in protic solvents. In HTFA (TFA = trifluoroacetate), >20% methane conversion with >85% selectivity for MeTFA have been achieved. The addition of substoichiometric amounts of chloride is essential, and for methane the conversion increases from 20%. The reaction also proceeds in aqueous HTFA as well as acetic acid to afford methyl acetate. 13C labeling experiments showed that less than 2% of methane is overoxidized to 13CO2 at 15% conversion of 13CH4. The system is selective for higher alkanes: 30% ethane conversion with 98% selectivity for EtTFA and 19% propane conversion that is selective for mixtures of the mono- and difunctionalized TFA esters. Studies of methane conversion using a series of iodine-based reagents [I2, ICl, ICl3, I(TFA)3, I2O4, I 2O5, (IO2)2S2O 7, (IO)2SO4] indicated that the chloride enhancement is not limited to iodate.
- Fortman, George C.,Boaz, Nicholas C.,Munz, Dominik,Konnick, Michael M.,Periana, Roy A.,Groves, John T.,Brent Gunnoe
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p. 8393 - 8401
(2014/06/24)
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- Direct catalytic oxidation of lower alkanes in ionic liquid media
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Immobilization of rhodium (palladium)-copper-chloride catalytic systems in ionic liquids as high-boiling-point solvents affects the distribution of propane oxidation products: the acetone yield increases and the yield of alcohols decreases. Propane is oxidized to acetone, bypassing the isopropanol formation step. Methane is oxidized under more severe conditions than propane, giving methyl trifluoroacetate as the main product. Mechanisms of action of the catalytic systems based on rhodium and palladium are close to each other and likely include oxo or peroxo complexes as intermediates.
- Chepaikin,Bezruchko,Menchikova,Moiseeva,Gekhman
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p. 374 - 381
(2015/02/19)
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- Selective CH Functionalization of Methane, Ethane, and Propane by a Perfluoroarene Iodine(III) Complex
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Direct partial oxidation of methane, ethane, and propane to their respective trifluoroacetate esters is achieved by a homogeneous hypervalent iodine(III) complex in non-superacidic (trifluoroacetic acid) solvent. The reaction is highly selective for ester formation (>99 %). In the case of ethane, greater than 0.5 M EtTFA can be achieved. Preliminary kinetic analysis and density functional calculations support a nonradical electrophilic CH activation and iodine alkyl functionalization mechanism. Gas up: Direct partial oxidation of methane, ethane, and propane to their respective trifluoroacetate (TFA) esters is achieved by a homogeneous hypervalent iodine(III) complex in non-superacidic solvent (HTFA). The reaction is highly selective, and for ethane, greater than 0.5 M Et=TFA can be achieved. Preliminary kinetic analysis and density functional calculations support a nonradical electrophilic CH activation and iodine alkyl functionalization mechanism.
- Konnick, Michael M.,Hashiguchi, Brian G.,Devarajan, Deepa,Boaz, Nicholas C.,Gunnoe, T. Brent,Groves, John T.,Gunsalus, Niles,Ess, Daniel H.,Periana, Roy A.
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supporting information
p. 10490 - 10494
(2016/02/18)
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- OXIDATION OF ALKANES TO ALCOHOLS
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The invention provides processes and materials for the efficient and cost- effective functionalization of alkanes, such as methane from natural gas, to provide esters, alcohols, and other compounds. The method can be used to produce liquid fuels such as methanol from a natural gas methane-containing feedstock. The soft oxidizing electrophile, a compound of a main group, post- transitional element such as Tl, Pb, Bi, and I, that reacts to activate the alkane C- H bond can be regenerated using inexpensive regenerants such as hydrogen peroxide, oxygen, halogens, nitric acid, etc. Main group compounds useful for carrying out this reaction includes haloacetate salts of metals having a pair of available oxidation states, such as Tl, Pb, Bi, and I. The inventors herein believe that a unifying feature of many of the MXn electrophiles useful in carrying out this reaction, such as Tl, Pb, and Bi species, is their isoelectronic configuration in the alkane -reactive oxidation state; the electrons having the configuation [Xe]4f145d10, with an empty 6s orbital. However, the iodine reagents have a different electronic configuration.
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Page/Page column 12; 13; 14
(2014/09/03)
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- Main-group compounds selectively oxidize mixtures of methane, ethane, and propane to alcohol esters
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Much of the recent research on homogeneous alkane oxidation has focused on the use of transition metal catalysts. Here, we report that the electrophilic main-group cations thallium(III) and lead(IV) stoichiometrically oxidize methane, ethane, and propane, separately or as a one-pot mixture, to corresponding alcohol esters in trifluoroacetic acid solvent. Esters of methanol, ethanol, ethylene glycol, isopropanol, and propylene glycol are obtained with greater than 95% selectivity in concentrations up to 1.48 molar within 3 hours at 180°C. Experiment and theory support a mechanism involving electrophilic carbon-hydrogen bond activation to generate metal alkyl intermediates. We posit that the comparatively high reactivity of these d 10 main-group cations relative to transition metals stems from facile alkane coordination at vacant sites, enabled by the overall lability of the ligand sphere and the absence of ligand field stabilization energies in systems with filled d-orbitals.
- Hashiguchi, Brian G.,Konnick, Michael M.,Bischof, Steven M.,Gustafson, Samantha J.,Devarajan, Deepa,Gunsalus, Niles,Ess, Daniel H.,Periana, Roy A.
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p. 1232 - 1237
(2014/04/03)
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- Water-promoted palladium catalysts for methane oxidation
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A water-tolerant, active and high-selective palladium catalyst, (2,2′-bipyridine) dichloropalladium(II) is proposed for the oxidation of methane to a methanol derivative with molecular oxygen as the oxidant at temperatures below 120 C, and its activity can be increased by three times at 100 C when the volume ratio of water to CF3COOH solvent is 1:5. In addition, the addition of perfluorooctane can enhance the yield of methanol further.
- Yuan, Jiongliang,Wang, Yan,Hao, Cunjiang
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p. 610 - 615
(2013/07/19)
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- Spiroligozymes for transesterifications: Design and relationship of structure to activity
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Transesterification catalysts based on stereochemically defined, modular, functionalized ladder-molecules (named spiroligozymes) were designed, using the inside-out design strategy, and mutated synthetically to improve catalysis. A series of stereochemically and regiochemically diverse bifunctional spiroligozymes were first synthesized to identify the best arrangement of a pyridine as a general base catalyst and an alcohol nucleophile to accelerate attack on vinyl trifluoroacetate as an electrophile. The best bifunctional spiroligozyme reacted with vinyl trifluoroacetate to form an acyl-spiroligozyme conjugate 2.7 × 103-fold faster than the background reaction with a benzyl alcohol. Two trifunctional spiroligozymes were then synthesized that combined a urea with the pyridine and alcohol to act as an oxyanion hole and activate the bound acyl-spiroligozyme intermediate to enable acyl-transfer to methanol. The best trifunctional spiroligozyme carries out multiple turnovers and acts as a transesterification catalyst with k1/kuncat of 2.2 × 103 and k2/kuncat of 1.3 × 102. Quantum mechanical calculations identified the four transition states of the catalytic cycle and provided a detailed view of every stage of the transesterification reaction.
- Kheirabadi, Mahboubeh,?elebi-?l?üm, Nihan,Parker, Matthew F. L.,Zhao, Qingquan,Kiss, Gert,Houk,Schafmeister, Christian E.
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supporting information
p. 18345 - 18353
(2013/01/15)
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- The Zn2+ complex of 1,4,7,10-tetraazacyclododecane as an artificial nucleobase
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{2-Deoxy-3-O-[2-cyanoethoxy(diisopropylamino)phosphino]-5-O-(4, 4'-dimethoxytrityl)-D-erythro-pentofuranosyl}-N-{2-[4,7,10-tris(2,2, 2-trifluoroacetyl)-1,4,7,10-tetraazacyclododecan-1-yl]ethyl}acetamide (1) was prepared and incorporated into a 2'-O-methyl oligoribonucleotide. The hybridization of this oligonucleotide with complementary 2'-O-methyl oligoribonucleotides incorporating one to five uracil bases opposite to the azacrown structure was studied in the absence and presence of Zn2+. Introduction of Zn2+ moderately stabilized the duplex with U-bulged targets. Copyright Taylor and Francis Group, LLC.
- Laine, Maarit,Aromaa, Maria,Virta, Pasi,Lonnberg, Tuomas,Poijaervi-Virta, Paeivi,Loennberg, Harri
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experimental part
p. 609 - 618
(2011/12/15)
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- Joint experimental and DFT study of the gas-phase unimolecular elimination kinetic of methyl trifluoropyruvate
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The elimination kinetics of methyl trifluoropyruvate in the gas phase was determined in a static system, where the reaction vessel was always deactivated with allyl bromide, and in the presence of at least a 3-fold excess of the free-radical chain inhibitor toluene. The working temperature range was 388.5-430.1 °C, and the pressure range was 38.6-65.8 Torr. The reaction was found to be homogeneous and unimolecular and to obey a first-order rate law. The products of the reaction are methyl trifluoroacetate and CO gas. The Arrhenius equation of this elimination was found to be as follows: log k1 (s-1) = (12.48 ± 0.32) - (204.2 ± 4.2) kJ mol -1(2.303RT)-1 (r = 0.9994). The theoretical calculation of the kinetic and thermodynamic parameters and the mechanism of this reaction were carried out at the B3LYP/6-31G(d,p), B3LYP/6-31++G(d,p), MPW1PW91/6-31G(d,p), MPW1PW91/6-31++G(d,p), PBEPBE/6-31G(d,p), and PBEPBE/6-31G++(d,p) levels of theory. The theoretical study showed that the preferred reaction channel is a 1,2-migration of OCH3 involving a three-membered cyclic transition state in the rate-determining step.
- Tosta, Maria M.,Mora, Jose R.,Cordova, Tania,Chuchani, Gabriel
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scheme or table
p. 7892 - 7897
(2011/01/10)
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- Catalytic oxidation of hydrocarbons of natural and oil gas
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Alkane oxidation by O2 and CO in the presence of Rh-, Pd-, and Pt-containing catalytic systems leads to the product of C-H bond oxidation and the products of C-C bond oxidative destruction. A deuterated methyl group in acetic acid is observed in the oxidation of n-propane in a deuterium-donor medium. The possible mechanisms of alkane C2-C4 conversion are proposed.
- Chepaikin,Bezruchenko,Menchikova,Moiseeva,Gekhman
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experimental part
p. 332 - 337
(2011/04/26)
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- Homogeneous catalytic oxidation of light alkanes: C-C bond cleavage under mild conditions
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The combined oxidation of CO and C2-C4 alkanes (associated petroleum gas and natural gas components) under the action of oxygen in trifluoroacetic acid solutions in the presence of rhodium and copper chlorides was accompanied by the oxidative degradation of C-C bonds in a hydrocarbon chain with the formation of carbonyl compounds, alcohols, and esters. For butane and isobutane, the reaction path with C-C bond cleavage was predominant. The buildup curves of isobutane oxidation products (both with the retention and with the degradation of the chain) were S-shaped and characterized by the same induction period; they did not pass through a maximum. A reaction scheme was proposed to reflect the main special features of the mechanism of transformations occurring in the O2/Rh/Cu/Cl- oxidation system.
- Chepaikin,Bezruchenko,Menchikova,Moiseeva,Gekhman
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experimental part
p. 666 - 671
(2011/02/16)
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- Oxidation Catalyst
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A catalyst for the oxidation of an alkane to an oxygenated hydrocarbon in the presence of oxygen as a first oxidant, comprising a redox active metal centre that can be present in an oxidised and in a reduced form, an acid, a second oxidant for oxidising the reduced form of the redox active metal centre, and a source of nitrous oxide.
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Page/Page column 3
(2009/08/18)
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- Synthesis and antifungal activity of β mrifluoroalkyl aminovinyl ketone derivatives
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Ten β-trifluoroalkyl aminovinyl ketone derivatives were synthesized, and their inhibitory effects on several phytopathogenic fungi, an oomycete and plants were assessed. The various compounds were fungitoxic at the 10-100 μM range, with (Z)-3-amino-4,4,4-trifluoro-1-(4-chlorophenyl)but-2-en1-one exhibiting the highest inhibitory effect on most of the test pathogens. Alternarla alternata and Neurospora crassa were the most tolerant and sensitive fungi to the compounds, respectively. We propose that (Z)-3-amino-4,4,4- trifluoro-1-phenylbut-2-en-1-one is the minimal structural requirement for a β-trifluoroalkyl aminovinyl ketone fungitoxic derivative. 2009 American Chemical Society.
- Gellerman, Gary,Pariente, Natali,Zahi, Paz,Shnaiderman, Anat,Yarden, Oded
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experimental part
p. 8303 - 8307
(2010/07/15)
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- Quinone tailored selective oxidation of methane over palladium catalyst with molecular oxygen as an oxidant
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With the in situ generated H2O2 tailored by the addition of p-tetrachlorobenzoquinone, the product can be effectively steered towards either HCOOH or the methanol derivative CF3COOCH3 during the direct oxidation of methane with molecular oxygen over palladium catalyst.
- Fan, Yafang,An, Zengjian,Pan, Xiulian,Liu, Xiumei,Bao, Xinhe
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supporting information; experimental part
p. 7488 - 7490
(2010/05/01)
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- 1-(a-Aminobenzyl)-2-naphthol: A new chiral auxiliary for the synthesis of enantiopure a-aminophosphonic acids
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A new diastereoselective synthesis of a-aminophosphonates has been developed, based on the reaction, in the presence of trifluoroacetic acid, of trialkyl phosphites with chiral imines derived from (R)- or (S)-l-(ot- aminobenzyl)-2-naphthol. The reaction p
- Metlushka, Kirill E.,Kashemirov, Boris A.,Zheltukhin, Viktor F.,Sadkova, Dilyara N.,Buechner, Bernd,Hess, Christian,Kataeva, Olga N.,McKenna, Charles E.,Alfonsov, Vladimir A.
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supporting information; experimental part
p. 6718 - 6722
(2010/02/28)
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- Oxidation of Methane to Methanol using a Catalyst Containing a Transition Metal
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A process for the oxidation of methane to methanol has been developed. The process involves contacting a gas stream, comprising methane, a solvent and an oxidizing agent with a catalyst at oxidation conditions to produce a methyl ester. Finally, the methyl ester is hydrolyzed to yield a methanol product stream. The catalyst comprises a transition metal component such as manganese oxide and an inorganic oxide such as silica. The transition metal component can be dispersed onto the inorganic oxide.
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Page/Page column 3; 4
(2008/12/04)
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- Process for the Production of Methanol from Methane using a Supported Transition Metal Catalyst
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A process for the selective oxidation of methane to methanol using a supported transition metal catalyst has been developed. Examples of the transition metals which can be used are copper and palladium, while an example of a support is silica. Optionally, the catalyst can contain a modifier component such as cesium. Generally the process involves contacting a gas stream, comprising methane, a solvent such as trifluoroacetic acid and an oxidizing agent such as air or hydrogen peroxide with the catalyst, at oxidation conditions to produce a methyl ester, e.g. methyl trifluoroacetate. Finally, the methyl ester is hydrolyzed to yield a methanol product stream.
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Page/Page column 3-4
(2008/12/08)
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- Oxidation of Methane to Methanol using a Bimetallic Catalyst
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A process for the oxidation of methane to methanol has been developed. The process involves contacting a gas stream, comprising methane, a solvent and an oxidizing agent with a bimetallic catalyst at oxidation conditions to produce a methyl ester. Finally, the methyl ester is hydrolyzed to yield a methanol product stream. The bimetallic catalyst comprises at least two transition metal components. One example of the catalytic component is a combination of cobalt and manganese.
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Page/Page column 2-3
(2008/12/08)
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- OXIDATION CATALYST
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A catalyst for the oxidation of an alkane to an oxygenated hydrocarbon in the presence of oxygen as a first oxidant, comprising a redox active metal centre that can be present in an oxidised and in a reduced form, an acid, a second oxidant for oxidising the reduced form of the redox active metal centre, and a source of nitrous oxide.
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Page/Page column 6-9
(2008/06/13)
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- Biomimetic trifunctional organocatalyst showing a great acceleration for the transesterification between vinyl ester and alcohol
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Trifunctional organocatalysts 1a and 1b mimicking the active site of serine hydrolases showed high catalytic activity with up to a 3 700 000-fold acceleration for the acyl-transfer reactions from vinyl trifluoroacetate to alcohol. The Royal Society of Chemistry.
- Ema, Tadashi,Tanida, Daisuke,Matsukawa, Tatsuya,Sakai, Takashi
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p. 957 - 959
(2008/09/21)
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- Synthesis of diethyl{[5-(3-fluorophenyl)-pyridine-2yl]methyl}phosphonate
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This application discloses a novel process for the preparation of phosphonate esters useful as intermediates in the preparation of himbacine analogs, themselves useful as thrombin receptor antagonists. The chemistry taught herein can be exemplified by the following scheme: wherein R9 is selected from alkyl, aryl heteroaryl and arylalkyl groups having 1 to 10 carbon atoms, and R11 is selected independently for each occurrence from alkyl, aryl heteroaryl and arylalkyl groups having 1 to 10 carbon atoms and hydrogen, X2 is Cl, Br, or I; X3 is selected from Cl and Br; and PdLn is a supported palladium metal catalyst or a soluble heterogeneous palladium catalyst. The L-derivatizing reagent is a moiety which converts the alcohol functional group of compound 137D to any leaving group which can be displaced by a triorgano-phosphite phosphonating agent.
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Page/Page column 14
(2008/06/13)
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- PROCESS FOR THE PRODUCTION OF METHANOL FROM METHANE USING A METAL TRIFLUOROACETATE CATALYST
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A process for converting methane to methanol using a homogeneous catalyst has been developed. The catalyst is a metal compound having an empirical formula of MxXm where M is a metal such as Pd, Cu, Co, and Mn, X is an anion such as acetate, trifluoroacetate, sulfate, propionate, “m” is the oxidation state of M, and “x” is the anion valence of X. Generally the process involves contacting a gas stream containing methane with the homogeneous catalyst and an oxidant such as hydrogen peroxide at oxidation conditions to produce methyl trifluoroacetate. Finally, the methyl trifluoroacetate is hydrolyzed to give a methanol product stream.
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Page/Page column 2
(2008/06/13)
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- Highly efficient direct carboxylation of propane into butyric acids catalyzed by vanadium complexes
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A direct and highly efficient carboxylation of propane by carbon monoxide into butyric acids (mainly isobutyric and, in a smaller amount, n-butyric), in the presence of potassium peroxodisulphate (K2S2O 8) and in trifluoroacetic acid solution, has been achieved by using a vanadium catalytic system based on Ca[V{ON(CH(CH3)COO) 2}2] (synthetic amavadine), its model compounds Ca[V{ON-(CH2COO)2}2] or [VO(N(CH 2CH2O)3}] - other simpler vanadium compounds, such as [VO(acac)2] or VOSO4, are less active. Overall yields (based on pro- ane) of carboxylic acids up to 70% and TON values up to 18.4 × 103 have been reached. The effects of various factors such as the propane and carbon monoxide pressures, temperature, time, catalyst amount and radical traps have been investigated, the reactions are shown to proceed via both C- and O-centred radicals, with K2S 2O8 playing the role of an oxidant via a free radical mechanism.
- Kirillova, Marina V.,Da Silva, Jose A. L.,Da Silva, Joao J. R. Frausto,Palavra, Antonio F.,Pombeiro, Armando J. L.
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p. 1765 - 1774
(2008/02/11)
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- Using Kamlet-Taft solvent descriptors to explain the reactivity of anionic nucleophiles in ionic liquids
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In this paper, we report the effect of ionic liquids on substitution reactions using a variety of anionic nucleophiles. We have combined new studies of the reactivity of polyatomic anions, acetate, trifuoroacetate, cyanide, and thiocyanide, with our previous studies of the halides in [C4C 1Py][Tf2N], [C4C1py][TfO], and [C4C1im][Tf2N] (where [C4C 1im]+ is 1-butyl-3-methylimidazolium and [C 4C1py]+ is 1-butyl-1-methylpyrrolidinium) and compared their reactivities, k2, to the same reactions in the molecular solvents dichloromethane, dimethylsulfoxide, and methanol. The Kamlet-Taft solvent descriptors (α, β, π*) have been used to analyze the rates of the reactions, which were found to have a strong inverse dependency on the α value of the solvent. This result is attributed to the ability of the solvent to hydrogen bond to the nucleophile, so reducing its reactivity. The Eyring activation parameters (ΔH? and ΔS?), while confirming the reaction mechanism, do not offer obvious correlations with the Kamlet-Taft solvent descriptors.
- Crowhurst, Lorna,Falcone, Ruben,Lancaster, N. Llewellyn,Llopis-Mestre, Veronica,Welton, Tom
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p. 8847 - 8853
(2007/10/03)
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