Showing papers on "Dehydrogenation published in 1979"
TL;DR: In this article, high-resolution electron energy loss spectroscopy (EELS) was used to study the adsorption of acetylene, enthylene, and cyclohexane at 150 K and subsequent decomposition after annealing to higher temperatures.
245 citations
220 citations
TL;DR: In this article, the anodic oxidation of glucose on platinum in phosphate buffer solution (pH=7.5) at potentials below 350 mV/RHE was investigated by cyclic voltammetry, chronoamperometry and adsorption measurements.
176 citations
TL;DR: In this article, the effects of preoxidation on catalytic rates and selectivity were found to be sensitive to the structure of the platinum surface, kink sites playing a particularly active role in the enhancement of dehydrogenation and hydrogenation activity by strongly bound oxygen.
124 citations
106 citations
TL;DR: The catalysts for the hydrogenation of nitriles under ambient conditions, producing primary amines selectively; they are also active for the dehydrogenation of amines at higher temperatures to give Nitriles or imines as mentioned in this paper.
Abstract: [RhH(PPri3)3] and [Rh2H2(µ-N2){P(cyclohexyl)3}4] are active catalysts for the hydrogenation of nitriles under ambient conditions, producing primary amines selectively; they are also active for the dehydrogenation of amines at higher temperatures to give nitriles or imines.
75 citations
74 citations
TL;DR: Both the H‐ and L‐gels could convert 4‐AD to ADD in the presence of PMS, the L‐gel showing a slightly higher conversion rate, while the immobilized cells were more stable, the stability of H‐gel and L-gel being almost the same.
Abstract: A cell suspension in a water‐insoluble organic solvent (benzene: n‐heptane, 1 : 1 by volume) of Nocardia rhodocrous (previously induced to synthesize steroid Δ1dehydrogenase) rapidly catalyzed the stoichiometric oxidation of 4‐androstene‐3,17‐dione (4‐AD) to androst‐l,4‐diene‐3,17‐dione (ADD) in the presence of phenazine methosulfate (PMS). High levels of 4‐AD or PMS reduced the conversion rates. No appreciable decrease in the conversion rate was observed on adding aqueous buffer solution to the thawed ceils (up to 9.4 g water/g dry cell). The whole cells were immobilized by entrapment in a hydrophilic gel (H‐gel) or a lipophilic gel (L‐gel) by use of a water‐soluble or water‐insoluble photocrosslinkable prepolymer. The reticula of H‐ and L‐gel matrices were impregnated with water and organic solvent, respectively. Both the H‐ and L‐gels could convert 4‐AD to ADD in the presence of PMS, the L‐gel showing a slightly higher conversion rate. Various lines of evidence indicate that the limiting factor is the penetration rate of 4‐AD into gel particles for the H‐gel, and the penetration rate of PMS for the L‐gel. The catalytic activities decreased considerably after several successive runs with the free cell suspension system, while the immobilized cells were more stable, the stability of H‐gel and L‐gel being almost the same.
69 citations
TL;DR: In this paper, tetralin was heated for various periods at temperatures between 300 and 450 °C without hydrogen or coal, and the products were analysed by capillary chromatography.
67 citations
TL;DR: In this paper, the same nonequilibrium mixture of 3- and 1-methylcyclohexene was obtained from the conversion of pure cis- or trans-2-methyl cyclohexanol over this catalyst, suggesting a common intermediate for dehydration, dehydrogenation, and cis-trans isomerization of the alcohol.
Abstract: Conversion of 2-butanol, 2- and 3-pentanol, 2-hexanol, 2- and 4-octanol, and 4-methyl- and 4,4-dimethyl-2-pentanol at 235/sup 0/-290/sup 0/C and 1 atm alcohol for 4-6 hr over zirconia catalysts prepared from various zirconium salts by precipitation and thermally pretreated in hydrogen or air gave mixtures of the corresponding ketones and alkenes. Many samples pretreated in hydrogen were very selective for dehydration of secondary (but not tertiary) 2-alkanols to alkenes, and two of them showed over 95Vertical Bar3< selectivity for 1-alkenes; the oxygen-treated catalysts were nonselective in most cases. Some of the catalysts showed high dehydrogenation selectivities for the 3- and 4-alkanols. The same nonequilibrium mixture of 3- and 1-methylcyclohexene was obtained from the conversion of pure cis- or trans-2-methylcyclohexanol over this catalyst, suggesting a common intermediate for dehydration, dehydrogenation, and cis-trans isomerization of the alcohol. Over-all, zirconia catalysts resembled thoria, but were quite different from titania and hafnia.
49 citations
TL;DR: In this article, it was shown that the specific activity for the formation of butadiene from 1-butene may be directly related to the concentration of antimony cations at the surface.
TL;DR: In this paper, the CS bond cleavage reactions of tetrahydrothiophene and but-1-thiol with and without hydrogen were examined at relatively low pressures and temperatures over three related Mo Al 2 O 3 catalysts; one was unpromoted with Co and the others had different Co contents.
TL;DR: In this paper, the application of ion cyclotron resonance spectroscopy to the study of organometallic reactions is described, and a method for the determination of metal-hydrogen, metal-carbon and metal-ligand bond dissociation energies and representative results are given.
Abstract: The application of ion cyclotron resonance spectroscopy to the study of organometallic reactions is described. Methodology is outlined for the determination of metal-hydrogen, metal-carbon and metal-ligand bond dissociation energies and representative results are given. These data are of fundamental importance in understanding the reactions of organic molecules at transition metal centers. Decarbonylation of aldehydes and dehydrogenation of alkanes are treated as examples of oxidative addition processes. Elimination of methane from hydrido methyl complexes exemplifies the study of reductive elimination reactions. Additional examples include studies of the acylation and alkylation of metal complexes, and the reactions of molecular hydrogen with several coordinatively unsaturated species.
TL;DR: In this article, the hydrogenation/dehydrogenation catalytic activity of minerals commonly present in coal was investigated, and the extent of reaction undergone by the model tetralin/1,2-dihydronaphthalene/naphalene at 400 °C in the presence of these minerals was used to measure the catalytic activation.
TL;DR: In this article, the results for the oxidation of ethylbenzene by gaseous oxygen and upon the interaction with oxygen adsorbed on charcoal are shown to be the same.
Abstract: The oxidative dehydrogenation of ethylbenzene over a charcoal catalyst has been studied by the pulse technique. The styrene yields for the oxidation of ethylbenzene by gaseous oxygen and upon the interaction of ethylbenzene with oxygen adsorbed on charcoal are shown to be the same.
TL;DR: In this article, a metastable CC surface species is formed prior to complete fragmentation into carbon and hydrogen atoms, and a stepped surface degrades acetylene upon adsorption even at 150 K.
TL;DR: Basicity of the catalyst turns out to be more important for the transition state and, hence, the product formed, than steric factors as mentioned in this paper, which is always associated with an E1cB mechanism for dehydration.
TL;DR: In this paper, the authors used homogeneous systems containing the complexes MCl(C8H12)PPh3 (M = Rh and Ir), and heterogeneous systems with Rh and IR metals.
Patent•
29 Dec 1979
TL;DR: In this article, a slurry of Mc, V, and P oxides or oxyacids, in the approx ratio desired in product, was heated at 60-250OC and l atm-30kg/cm2 ; a heteropolyacid was crystd out The heteropolyacids are useful as dehydrogenation catalysts, eg. in prepg methacrylic acid from isobutyric acid.
Abstract: An aq slurry of Mc, V, and P oxides or oxyacids, in the approx ratio desired in product, was heated at 60-250OC and l atm-30kg/cm2 ; a heteropolyacid was crystd out The heteropolyacids are useful as dehydrogenation catalysts, eg, in prepg methacrylic acid from isobutyric acid Thus, powd MoO3 360, V2O5 638 and H3PO4 288g in 2l H2O were refluxed with air injection for 20 days, filtered, concd to 300ml, to obtain red crystals of H5M10V2PO40
TL;DR: In this article, the N-acetyl derivatives of the former thiones were prepared and the infrared, nuclear magnetic resonance, and ultraviolet spectral data of the above compounds were tabulated and discussed.
Abstract: 1,3-Diaryl-2-propen-1-ones 1 reacted with thiourea in the presence of sodium ethoxide to give 4,6-diaryl-3,4-dihydropyrimidine-2(1H)thiones 5 which upon dehydrogenation with 3 mol of ethanolic sodium ethoxide yielded the corresponding 4,6-diarylpyrimidine-2(1H)thiones 9. The N-acetyl derivatives of the former thiones were prepared. Infrared, nuclear magnetic resonance, and ultraviolet spectral data of the above compounds were tabulated and discussed.
TL;DR: Kaliumpermanganat kann in Form des Kupfersulfat-Komplexes (I) als Oxidationsmittel fur Carbinole eingesetzt werden as discussed by the authors.
Abstract: Kaliumpermanganat kann in Form des Kupfersulfat-Komplexes (I) als Oxidationsmittel fur Carbinole eingesetzt werden.
TL;DR: A kinetic study of the dehydrogenation of ethanol to acetaldehyde on an unsupported catalyst of base composition CuO-Cr2O3 was carried out in an isothermal reactor fed with ethanol 95% vol. in the temperature range 225-285°C with space velocities 1.5-7.5 LHSV at atmospheric pressure.
Abstract: A kinetic study of the dehydrogenation of ethanol to acetaldehyde on an unsupported catalyst of base composition CuO – Cr2O3 was carried out in an isothermal reactor fed with ethanol 95% vol. in the temperature range 225–285°C with space velocities 1.5–7.5 LHSV at atmospheric pressure.
The mechanism which was found suitable to describe the reaction was that of surface adsorption on dual sites.
Taking into account interphase and intraphase diffusion, the observed conversions of ethanol were reconstructed with a standard error below 10%, thus confirming the validity of the physical assumptions.
TL;DR: In this article, the hydrogen transfer from 1-phenyl-1-propanol to 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) was investigated.
TL;DR: As a model of flavin-dependent biological dehydrogenation, Flavin-sensitized photodehydrogenation and photodecarboxylation were studied by variation of substrate, flavin, pH and solvent.
Abstract: As a model of flavin-dependent biological dehydrogenation, flavin-sensitized photodehydrogenation and photodecarboxylation were studied by variation of substrate, flavin, pH and solvent. Evidence for the following rules is given. (1) When the reactive site of a photosubstrate is an alpha-carbon atom of the type CH-CO2-, decarboxylation is preferred over dehydrogenation, whereas the reverse is true for the neutral CH-CO2H. (2) Consequently these reactions do not exhibit a measurable isotope effect with C2H-CO2-, in contrast with the findings by Penzer, Radda, Taylor & Taylor [(1970) Vitam. Horm. (N.Y.) 28, 441--466], which could not be reproduced. When the substate does not contain a carboxylate group, isotope effects occur, in verification of previous reports, e.g. for benzyl alcohol C6H5-C2H20H. (3) The mechanism of flavin-sensitized substrate photodecarboxylation is assumed to consist in a primary carbanion fixation at the flavin nucleus (position 4a, 5 or 8) with concomitant liberation of CO2. This step is followed by rapid fragmentation of the adduct CH-Fl-red., provided that the substrate contains a functional and electron-donating group X, e.g. X = OH, OCH3 or NH2 (but not NH3+ !) in X CH-CO2-. (4) The minimal requirement for flavin-sensitized C-H dehydrogenation is the presence of a hydroxyl group. For example, methanol as substrate and solvent is dehydrogenated at pH sufficiently alkaline for detection of the presence of the active species CH3O-, whereas at more acidic pH substrate dehydrogenation is competing with flavin autophotolysis, which depends on the substituents in the flavin nucleus.
TL;DR: In this paper, the results of a kinetic study of the oxidative dehydrogenation of ethylbenzene to styrene over an organic catalyst (pyrolyzed polymerized acrylonitrile) are reported.
Abstract: The results of a kinetic study of the oxidative dehydrogenation of ethylbenzene to styrene over an organic catalyst (pyrolyzed polymerized acrylonitrile) are reported. The reaction is found to be second order in ethylbenzene and zero order in oxygen with an activation energy of 76.5 kJ/mol. The rate equation is: where R = 8.31 J/niol.K and concentration (CEtB) is expressed as mol/L. The catalyst is more active than conventional metal oxide catalysts and appears to be quite stable under reaction conditions. The results suggest that, using the PPAN catalyst, it may be possible to reduce the operating temperature of the oxidative dehydrogenation of ethylbenzene to about 250-300°C, thereby avoiding some of the problems of the present high temperature process.
TL;DR: In this article, the conversion of cyclohexane in the dehydrogenation reaction over MoO 3 γ-Al 2 O 3 catalysts, measured in a pulse reactor, increases with the metal oxide content.
TL;DR: Isomerically pure biliverdin IXa can be prepared in high yield through dehydrogenation of bilirubin IXa with chloranil-picric acid in chloroform containing t-butanol.
Abstract: Isomerically pure biliverdin IXa can be prepared in high yield through dehydrogenation of bilirubin IXa with chloranil-picric acid in chloroform containing t-butanol.