Bajus, M.; Vesely, V.; Leclercq, P.A.; Rijks, J.A. Published in:Industrial and Engineering Chemistry. Product Research and Development DOI:10.1021%2Fi360069a007 10.1021/i360069a007Published: 01/01/1979 Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Link to publication• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. 1, 1979 Gandhi, H. S., Sheief, M., J , Catal., 24, 241 (1972).Gregg, S. J., Sing, K. S. W., "Adsorption, Surface Area and Porosity", Academic Hirota, K., Kera, Y., Teratani, S., J . Phys. Chem., 59, 388 (1955 (1 973).(USSR) 15, 408 (1974). (1972). GENERAL ARTICLESShvets, V. A., Kazanskii, V. B., J . Catal., 25, 123 (1972). Shvets, V. A.. Sarichev, M. E., Kazanskii, V. B., J. Catal., 11, 378 (1968) , 1424 (1955). 3rd, 1964 (1965). Catalysis", Academic Press, New York, N.Y., 1967. 597 (1971. 1966.Received for review February 13, 1978 Accepted The thermal decomposition of heptane in the presence of steam was studied in a flow reactor with large inner surface. The experiments were performed at atmospheric pressure in a temperature range of 680-760 OC for a mass ratio of steam to hydrocarbon 3 : l . The reaction products were analyzed by gas chromatography. For the identification both comparison of retention indices with those of standard compounds and literature data and mass spectrometry were used. The conversion process appeared to be a first-order reaction with a frequency factor of 1.34 X 10'' s-' and an activation energy of 195.5 kJ mol-'. The composition of the mixture of reaction products was in agreement with the Rice-Kossiakoff theory, except for ethane and 1-hexene.
The main principles of solid‐phase extraction techniques are reviewed in this paper. Various solid sorbents can be used as a suitable trap for direct accumulation of organic compounds from aqueous solutions. The trapped analytes can be desorbed by elution with suitably chosen liquid phases. These preconcentration procedures can be considered as low performance liquid chromatography and the efficiency of the procedure can thus be related to the retention characteristics of the preconcentration column. The main sorbents used for trace enrichment purposes are also reviewed. Besides, the concise methodology, sample storage, and automation are discussed. The advantages of solid phase extraction as compared to liquid‐liquid extraction are given as well as some drawbacks of this method.
The chemical ionization mass spectra of free amino acids, their amides, methyl esters and Na-acetyl derivatives, using methane as reagent gas, are presented. The occurrence and fragmentation of ion-molecule reaction products are discussed. A preference for a 'head-to-tail' configuration of the association complex [2M + 11' is postulated to explain prominent fragmentation pathways of this complex. Interesting fragmentation pathways have been found with ornithine, arginine and ci trulline. I N T R O D U C T I O N IN CHEMICAL ionization (CI) mass spectrometry the molecules of a vaporized sample are ionized by a set of reagent ions in a series of ion-molecule reacti0ns.l to l5 The energy transferred by these reactions is lower than the energy of electron ionization (EI) and therefore fragmentation of the sample molecules is greatly decreased. For this reason CI mass spectrometry has been finding increasing use as a tool in the elucidation of the structures of a variety of organic compounds.16 to 28 Methane is often used as the reagent gas in CI mass spectrometry. The most abundant reacting species in the methane plasma are [CH,]+ (47 %), [C2H5]+ (41 %) and [C,H,]+ (6%). All three ionic species transfer groups to the sample molecules producing [M + HI+, [M + C,H,]+ and [M + C,H,]+ ions, respectively, (where M is the molecular weight of the compound under investigation). Initially, these 'adduct ions' appear to confuse the mass spectrum, but actually they have diagnostic value in the determination of M. In addition to the adduct ions, [2M + l]+ ionsfhave been found in the CI mass spectra of and alcohols,14 using isobutane as the reagent gas. Additionally [2M]+ ions were found with benzene.'In the framework of our investigations of oligopeptides we needed to obtain the CI mass spectra (with methane) of a series of natural amino acids, their amides, methyl esters and Nu-acetyl derivatives. We wish to report here on the occurrence and fragmentation of the [2M + 1]+ ion and other ion-molecule reaction products in the CI mass spectrometry of amino acids and their analogs. The CI mass spectra of free amino acids, using methane as the reagent gas, has been reported for ions with a mass equal to, or less than, [M + l]+ only.2f RESULTS FRAGMENTATION OF ION-MOLECULEThe CI mass spectra of the compounds studied are presented in Tables 1 to 4.
it possible to take a set of generic skeletal force constants and use these for deriving structures with acceptable accuracy. As we have shown, the skeletal force constants are not generally transferable. If, however, one only wishes to obtain good structures of linear metallocenes, these force constants can be obtained for the metals in Table VI11 by simply using those of ferrocene as a generic set, provided the correct equilibrium bond lengths and angles are used. This will probably apply even for somewhat strained linear metallocenes.Acknowledgment. This work was supported by grants from the National Institutes of Health. Homologation of Olefins with Methane on Transition MetalsTijs Koerts,+ Piet A. Leclercq Abstract: Alkylation of olefins using methane has been realized on transition metal catalysts. The main problem is to get methane dissociatively adsorbed together with an olefin. This is due to the difficult activation of the strong tetrahedral C-H bonds of methane. To react methane with an olefin, a reaction sequence is used consisting of three steps. First methane is dissociatively adsorbed between 600 and 800 K on a reduced transition metal catalyst. After cooling, an olefin is coadsorbed at a temperature between 300 and 400 K. Upon subsequent hydrogenation carbon-carbon bond formation occurs. The mechanism appears to be related to that occurring in the Fischer-Tropsch reaction. After hydrogenation the reaction cycle can be repeated. Methane addition to ethene, propene, and acetylene is demonstrated to occur using silica-supported ruthenium and cobalt catalysts. With 13CH4 it was shown that propane and butane are formed both by self-homologation of ethene and propene, respectively, as well as by methane incorporation. Carbon scrambling according to the metathesis reaction is very slow.
DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:
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