Isotope effects in the oxidative functionalization of methane in the presence of rhodium-containing homogeneous catalytic systems

Чепайкин, Е. Г.; Bezruchenko, A. P.; Boǐko, G. N.; Гехман, А. Е.; Моисеев, И. И.

doi:10.1134/s0023158406010034

Cited by 26 publications

(5 citation statements)

References 19 publications

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“…Chepaikin and co-workers − found that both acetic acid (HOAc) and trifluoroacetic acid (HOTFA) accelerate the reaction (compared to no added acid) in the RhCl 3 /NaCl/KI system. When the less coordinating HOTFA was used in place of perfluorobutyric acid utilized by Sen, the authors report faster catalytic rates with less selective product distribution.…”

Section: Catalytic Systems That Utilize O2/o2-regenerable Oxidants An...mentioning

confidence: 96%

Homogeneous Functionalization of Methane

et al. 2017

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One of the remaining "grand challenges" in chemistry is the development of a next generation, less expensive, cleaner process that can allow the vast reserves of methane from natural gas to augment or replace oil as the source of fuels and chemicals. Homogeneous (gas/liquid) systems that convert methane to functionalized products with emphasis on reports after 1995 are reviewed. Gas/solid, bioinorganic, biological, and reaction systems that do not specifically involve methane functionalization are excluded. The various reports are grouped under the main element involved in the direct reactions with methane. Central to the review is classification of the various reports into 12 categories based on both practical considerations and the mechanisms of the elementary reactions with methane. Practical considerations are based on whether or not the system reported can directly or indirectly utilize O as the only net coreactant based only on thermodynamic potentials. Mechanistic classifications are based on whether the elementary reactions with methane proceed by chain or nonchain reactions and with stoichiometric reagents or catalytic species. The nonchain reactions are further classified as CH activation (CHA) or CH oxidation (CHO). The bases for these various classifications are defined. In particular, CHA reactions are defined as elementary reactions with methane that result in a discrete methyl intermediate where the formal oxidation state (FOS) on the carbon remains unchanged at -IV relative to that in methane. In contrast, CHO reactions are defined as elementary reactions with methane where the carbon atom of the product is oxidized and has a FOS less negative than -IV. This review reveals that the bulk of the work in the field is relatively evenly distributed across most of the various areas classified. However, a few areas are only marginally examined, or not examined at all. This review also shows that, while significant scientific progress has been made, greater advances, particularly in developing systems that can utilize O, will be required to develop a practical process that can replace the current energy and capital intensive natural gas conversion process. We believe that this classification scheme will provide the reader with a rapid way to identify systems of interest while providing a deeper appreciation and understanding, both practical and fundamental, of the extensive literature on methane functionalization. The hope is that this could accelerate progress toward meeting this "grand challenge."

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Section: Catalytic Systems That Utilize O2/o2-regenerable Oxidants An...mentioning

confidence: 96%

Homogeneous Functionalization of Methane

et al. 2017

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“…6 In the absence of CO, neither methane nor the acid are involved in the reactions. It was found that under the experimental conditions used the amount of methyl acetate exceeds the amount of the loaded catalyst (rhodium) by at least an order of mag nitude.…”

Section: Resultsmentioning

confidence: 99%

Uncommon oxidative transformations of acetic and propionic acids

et al. 2011

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The oxidative decarbonylation of acetic and propionic acids with the formation of the corresponding alcohol and alkyl carboxylate is observed in the Rh III /Cu I,II /Cl -catalytic sys tem in the presence of О 2 and CO. The decarbonylation of propionic acid in a deuterated solvent results in the substitution of hydrogen atoms by deuterium in the alkyl part of the products to form CH 2 DCOOD (CHD 2 COOH) and CHD 2 COOD (CD 3 COOH). The subse quent decarbonylation of deuterated acetic acids affords the corresponding deuteromethanols detected as esters with propionic and deuteroacetic acids. The substitution of the hydrogen atom by deuterium in the alkyl part of molecules of the products of oxidative decarbonylation of propionic acid, when the reaction is carried out in a deuterated solvent, indicates that propionic acid behaves as saturated hydrocarbon and blocks the oxidation of poorly soluble methane. Unlike propionic acid, acetic acid enters only the oxidative decarbonylation reaction and does not block methane oxidation.Interest in chemistry of carboxylic acids is generated by their role of biomass treatment aimed at producing diesel fuel. The presence of the carboxyl group decreases the energy content of the fuel. Therefore, one of the prob lems, namely, removal of the carboxyl group from fatty acids of lipids, can be solved by the decarbonylation of the acid followed by the dehydration of the alcohol. 1 In the present work, the decarbonylation of propionic and acetic acids under mild conditions (95 °С) was studied. It has previously 2 been found that the decarbonylation of stearic acid on the rhodium catalysts occurs only at 240-280 °С. ExperimentalThe following reagents and materials were used: RhCl 3 •(H 2 O) n (34.5 wt.% Rh), NaCl, CuO, NaCl, H 2 SO 4 , and HClO 4 (reagent grade), as well as H 2 O (bidistillate). Acetic acid (reagent grade) was distilled, C 2 H 5 COOH (Merck) was used as received, heptane (standard) was distilled off, and dioxane (re agent grade) was refluxed for 2 h above metallic sodium and then distilled. Methane (99.8%), carbon monoxide (99.9%), oxygen (99.9%), helium (trade mark A), nitrogen (special purity grade), hydrogen (99.0%), and deuterated compounds D 2 O (99.9 at.%), CD 3 COOD (99.5 at.%), and D 2 SO 4 (98.0 at.%) were used with out purification; and CD 4 (98.2 at.%) was condensed twice at the temperature of liquid nitrogen and then evaporated at -(60-50) °С to remove heavy admixtures, for instance, CCl 4 .Catalytic experiments were carried out in a 34 cm 3 Fluoro plast lined stainless steel reactor using the earlier described pro cedure. 3,4 In a typical experiment on methane oxidation, an autoclave was loaded with 6.25•10 -3 mmole of RhCl 3 and 18.75•10 -3 mmole of NaCl as solutions (0.25 g) in D 2 O; [RhCl 3 ] = 2.5•10 -3 mol L -1 and [NaCl] = 7.5•10 -3 mol L -1 . Then a 0.96•10 -3 М D 2 SO 4 solution (0.25 g) in D 2 O, 2.27 g of CD 3 COOD, and 10 mg of CuO were added. The autoclave was fed with the following gases: methane (6.0 MPa), oxygen (0.56 MPa), and carbon monoxide ...

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“…The system did not catalyze the H-D exchange of methane with the medium. For methyltrifluoro acetate as a major product, k CH4 /k CD4 was found [18] to have a value of 4.34 ± 0.16 (Table 2). …”

Section: Trifluoroacetic Acid-watermentioning

confidence: 96%

“…In the Rh-I-Cl system, this is HOI, whereas in the Rh-Cu-Cl system these are H 2 O 2 , peroxides of Rh or Cu or heteronuclear peroxides of Rh and Cu [8,18]. The yield of oxygenates as a function of [NaCl] shows a well pronounced maximum at 2.0 × 10 -2 M followed by a gradual decline.…”

Section: Reactions Of Methane Catalyzed By the Rhodium-copper (Iron)-mentioning

confidence: 99%