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1Author    Dietmar Kuck, Hans-Friedrich GrützmacherRequires cookie*
 Title    Der Einfluß der Kettenlänge auf die massenspektrometrigche Fragmentierung höherer l.co-Diphenylalkane The Influence of the Chain Length on the Mass Spectrometric Fragmentation of Higher 1, co-Diphenylalkanes  
 Abstract    The mass spectrometric fragmentation of l,co-diphenylalkanes (2 < co < 22) has been studied in order to elucidate the effect of the chain length on the reactions of unstable and metastable molecular ions with respect to the occurrence of internally solvated ions in the gas phase. The unstable molecular ions of all l,co-diphenylalkanes react predominantly by formation of C?H7+ and C7Hg + " ions, the latter ones are also formed by metastable molecular ions. Neither the variation of the relative abundances of these fragment ions with the chain length nor the fragmentation of specifically deuterated molecular ions indicate any internal solvation in the reacting ions. Inspite of the localized activated C-H bonds at the benzylic positions, these "activated" H atoms are not involved in intra-molecular hydrogen exchange reactions or the formation of C7Hs + ' ions (with the exception of co = 3). Especially the higher homologues (co > 12) react very similarly to the molecular ions of 1-phenylalkanes, while the fragmentation of the lower homologues (co < 6) is determined by specific ("vinculoselective") competitive reactions, e.g. loss of CvH?' and CsHs. 
  Reference    Z. Naturforsch. 34b, 1750—1764 (1979); eingegangen am 12. Juli 1979 
  Published    1979 
  Keywords    Mass Spectrometry, 1, co-Diphenylalkanes 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-1750.pdf 
 Identifier    ZNB-1979-34b-1750 
 Volume    34 
2Author    H. Parlar, S. Nitz, A. Michna, F. KörteRequires cookie*
 Title    Ein Beitrag zur Zusammensetzung des Insektizides "Toxaphen®" Gaschromatographisch-massenspektroskopische Charakterisierung eines öligen und eines kristallinen Anteils des technischen Toxaphens und dessen insektizide Wirksamkeit A Contribution to the Composition of the Insecticide "Toxaphene®" Gaschromatographic-Masspectroscopical Characterisation of the Oily and the Crystalline Fraction of Technical Toxaphene and their Insecticidal Activity  
 Abstract    Technical Toxaphene can be separated in two fractions by recrystallisation which are investigated with the help of GC/MS and toxicological methods. Especially the Retro-Diels-Alder-fragmentations give specific informations on the structure of highly chlorinated bornane derivatives representing the main components of the technical mixture. For this study lower chlorinated bornanes are used as model substances. Toxicological investigations show that both fractions have lower activity than technical toxaphene. 
  Reference    Z. Naturforsch. 33b, 915—923 (1978); eingegangen am 10. Mai 1978 
  Published    1978 
  Keywords    Toxaphene, Chlorinated Bornane, Mass Spectrometry, Toxicology 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-0915.pdf 
 Identifier    ZNB-1978-33b-0915 
 Volume    33 
3Author    KlausG. Heumann, Paul Roßmann, Anni Schwarz, Alfred WindfelderRequires cookie*
 Title    Abhängigkeit der Chlor-Isotopenseparation vom Vernetzungsgrad eines stark basischen Anionenaustauschers Dependence of Chlorine Isotope Separation on the Degree of Cross Linkage of a Strongly Basic Anion Exchange Resin  
 Abstract    Using ion exchange chromatography, the dependence of the chlorine isotope separation on the degree of cross linkage of a strongly basic anion exchange resin was investigated. With increasing degree of cross linkage the elementary separation effect for the two stable isotopes 35 C1 and 37 C1 increases. In all experiments 35 C1~ is enriched in the resin phase, whereas 37 C1~ is enriched in the solution, using 0.1 M NaNC>3 as an eluant. Within the degree of cross linkage of 2 to 10 per cent investigated, there is a linear correlation of the elementary separation effect of the chlorine isotopes with the selectivity coefficient between the ions NO3"" and Cl -. The results show that the electrolyte behavior of anionic isotope exchange reactions is comparable with that of cations. The 35 C1/ 37 C1 isotope ratio is determined using thermal ionization mass spectrometry. Untersuchungen von Isotopieeffekten bei hetero-genen Ionenaustauschreaktionen sind bereits bei einigen Kationen durchgeführt w T orden, wie z.B. 
  Reference    Z. Naturforsch. 34b, 406—411 (1979); eingegangen am 4. Dezember 1978 
  Published    1979 
  Keywords    Isotope Separation, Chlorine, Ion Exchange Chromatography, Mass Spectrometry 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-0406.pdf 
 Identifier    ZNB-1979-34b-0406 
 Volume    34 
4Author    KlausK. Mayer, Ilona Matolović, Erich Fischer, Carl DjerassiRequires cookie*
 Title    Mass Spectrometric Investigations on Unsaturated Hydrocarbons: Halogen Migration in the Molecular Ions of Acetylenes and Alkenes  
  Reference    Z. Naturforsch. 34b, 1612—1614 (1979); eingegangen am 13. Juni 1979 
  Published    1979 
  Keywords    Mass Spectrometry, Halogen Migration, Simple Alkenes, Alkynes 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-1612_n.pdf 
 Identifier    ZNB-1979-34b-1612_n 
 Volume    34 
5Author    Eberhard Hohaus, Wolfgang Riepe, Klaus Wessendorf, LaRequires cookie*
 Title    Massenspektrometrische Untersuchungen an Borchelaten, V [1] Fragmentierung borhaltiger aromatischer Azoverbindungen Mass Spectrometric Investigation of Boron Chelates, V [1] Fragmentation of Aromatic Azo Compounds Containing Boron M+ M+-R M+-RH A M+-C6H5N2 C6H5N2+ C6H5 +  
 Abstract    Differing fragmentation of boron chelates of aromatic azo compounds confirms the structural formulae la-7c, presented in [2]. More significant differences are caused by the substituent of the boron R (F instead of C6H5). Although certain rules can be deduced by the substitution of F for CeHs with regard to the change in intensity of the ions M+, M+-R (and others), in some cases the stable aromatic azo system causes a significant change in the fragmentation as compared with that of azomethine chelates. The chelates 7 eliminate "RH" and show no molecular ion. Apparently a second chelate ring is closed before further fragmentation can start. Fragmentation of 7 a and b is analogous to 5. Einführung Die Massenspektrometrie nimmt bei der analyti-schen Überprüfung und der Konstitutionsaufklä-rung von Borchelaten eine besondere Stellung ein, weil umfangreiches Material mit verschiedensten Komplexbildnern vorliegt. Deshalb werden die Er-gebnisse der Azochelate [2] mit denen der früher dargestellten verglichen. Die Numerierung der Che-late erfolgt nach dem Formelschema in [2]. Vergleich der Fragmentierungen Chelate 1 und 2: Das Massenspektrum von la zeigt nur eine geringe relative Intensität für das Tab. I. Nr. 
  Reference    Z. Naturforsch. 35b, 316—318 (1980); eingegangen am 8. Oktober 1979 
  Published    1980 
  Keywords    Mass Spectrometry, Boron Azo Chelates, Fragmentation 
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 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-0316.pdf 
 Identifier    ZNB-1980-35b-0316 
 Volume    35 
6Author    Hartmut Klein, Wittko Francke, WilfriedA. KönigRequires cookie*
 Title    Studien über Wespengift, I Niedermolekulare Bestandteile des Giftblasenextraktes von Paravespula vulgaris Studies on Wasp Venom, I Low Molecular Weight Constituents of Venom Sac Extracts from Paravespula vulgaris  
 Abstract    Low molecular weight constituents of 3400 venom sacs of Paravespula vulgaris were extracted with water, diluted acetic acid, and methanol. After conversion to volatile derivatives carbohydrates, amino acids, fatty acids, other constituents of phospho lipids, and biogenic amines were identified by gas chromatography and mass spectrometry. Quantitative analysis was achieved for amino acids by amino acid analysis and for glucose by an enzymatic assay. Results are discussed with regard to biosynthesis of wasp toxins and phylogenetic aspects of hymenopteran venoms. 
  Reference    Z. Naturforsch. 36b, 757—762 (1981); eingegangen am 11. Februar 1981 
  Published    1981 
  Keywords    Wasp Venom, Gas Chromatography, Mass Spectrometry 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-0757.pdf 
 Identifier    ZNB-1981-36b-0757 
 Volume    36 
7Author    Bernhard Ciommer, Helmut Schwarz, Azzedine Maaroufi, ManfredT. Reetz, Karsten LevsenRequires cookie*
 Title    Silyl-Assistierte Etherspaltung bei Radikalkationen von Hydroxylaminderivaten [1] Silyl-Assisted Ether Cleavage in Radical Cations of Hydroxylamine Derivatives [1]  
 Abstract    It is demonstrad by means of various mass spectrometric techniques that the dissociative ionization of N.N-bis-silylated hydroxylamine derivatives (5 a) and (5 b), giving rise to the cleavage of the (O-C) bond, is anchimerically assisted by migration of the trimethylsilyl group to the ether oxygen, thus generating ion (7). 
  Reference    Z. Naturforsch. 36b, 771—773 (1981); eingegangen am 11. März 1981 
  Published    1981 
  Keywords    Mass Spectrometry, Collisional Activation, Anchimeric Assistance, Silyl Ether 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-0771_n.pdf 
 Identifier    ZNB-1981-36b-0771_n 
 Volume    36 
8Author    Helmut Schwarz, Friedeich Borchers, Karsten LevsenRequires cookie*
 Title    Stoßaktivierungsmassenspektrometrie von Monoterpenen und Isomerisierung von C7H9 + -Ionen in der Gasphase Collisional Activation Mass Spectrometry of Monoterpenes and Isomerisation of Gaseous C7H9 + Ions  
  Reference    (Z. Naturforsch. 31b, 935—940 [1976]; eingegangen am 29. März 1976) 
  Published    1976 
  Keywords    Collisional Activation Spectra, Ion Structure, Isomerisation, Mass Spectrometry, Terpenes 
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 TEI-XML for    default:Reihe_B/31/ZNB-1976-31b-0935.pdf 
 Identifier    ZNB-1976-31b-0935 
 Volume    31 
9Author    Rupert Herrmann, Helmut SchwarzRequires cookie*
 Title    On the Isomerisation and Fragmentation of Butenoic Acid Methyl Esters under Electron Impact  
 Abstract    Ion On the contrary to the photochemical behavior the title compounds do not isomerise to a common intermediate prior to or during electron impact induced fragmentation. The unusual methyl elimination from the trans (2)-butenoic acid methyl ester probably is ac-companied by a concerted [1.3] methoxy rearrangement from the ester function on to the ß carbon atom. 
  Reference    (Z. Naturforsch. 31b, 1013—1014 [1976]; eingegangen am 22. März 1976) 
  Published    1976 
  Keywords    Structure, Neighbouring Group Participation, Alkoxy Rearrangement, Mass Spectrometry, Unsaturated Esters 
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 TEI-XML for    default:Reihe_B/31/ZNB-1976-31b-1013_n.pdf 
 Identifier    ZNB-1976-31b-1013_n 
 Volume    31 
10Author    Rupert Herrmann, Helmut SchwarzRequires cookie*
 Title    On the Mechanism of Substituent Interaction During bhe Electron Impact Induced Ether Cleavage from para-Substituted Methoxymethvl Benzenes  
 Abstract    The unusual methyl elimination from para-substituted methoxy-methyl benzenes has been elucidated. It can be shown that two entirely different mechanisms contribute to the reaction: i) intramolecular hydrogen transfer onto the benzene ring (7r-complex formation) and ii) substituent migration via ring expansion. Alternative mechanisms as for instance transanular protonation of the ester function or substituent migration via valence bond isomers are not involved in the formation of the [M-methyl]+-ions. 
  Reference    (Z. Naturforsch. 31b, 1667—1672 [1976]; eingegangen am 24. September 1976) 
  Published    1976 
  Keywords    Mass Spectrometry, Intramolecular Protonation, t-Complex, Rearrangement, Ring Expansion 
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 TEI-XML for    default:Reihe_B/31/ZNB-1976-31b-1667.pdf 
 Identifier    ZNB-1976-31b-1667 
 Volume    31 
11Author    I. Lüderwald, M. Przybylski, H. Ringsdorf, D. Silberhorn, H. Kaibacher, W. VoelterRequires cookie*
 Title    Untersuchung yon isomeren Tripeptiden und Derivaten des Thyrotropin-,Releasing" Hormons durch Elektronenstoß- und Felddesorptions-Massenspektrometrie Investigation of Isomeric Tripeptides and Thyrotropin-Releasing Hormone Derivatives by Electron Impact and Field Desorption Mass Spectrometry  
 Abstract    The complementary informations from field desorption and electron impact mass spectra of free tripeptides and thyrotropine releasing hormone derivatives can be used to determine primary structure and molecular weight. Characteristic and diagnostic frag-mentation pathways, the formation of diketopiperazines and the temperature-dependent tendency to form amine fragments and diketopiperazines will be discussed. 
  Reference    Z. Naturforsch. 33b, 809—817 (1978); eingegangen am 20. Januar 1978 
  Published    1978 
  Keywords    Mass Spectrometry, Sequence Determination, Isomeric Tripeptides, Thyrotropin-Releasing Hormone 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-0809.pdf 
 Identifier    ZNB-1978-33b-0809 
 Volume    33 
12Author    Helmut Schwarz, Chrysostomos Wesdemiotis, Thomas Weiske, Klaus-Peter Zeller, Roland MüllerRequires cookie*
 Title    H. Schwarz et al. * Methyl-Eliminierung aus dem metastabilen Homoadamantan-Radikalkation 219 Methyl Loss from Metastable Homoadamantane Cation Radical  
 Abstract    It is demonstrated that methyl loss from ionized homoadamantane (1) yields exclusively the 1-adamantyl cation (4); there is no experimental evidence for the formation of the secondary adamantyl cation (5). From both model calculations and the investigation of [4-13 C]-homoadamantane (la) and l(13 C-methyl)adamantane (2a) it is concluded, that 24% of the metastable homoadamantane cation radicals dissociate after one isomerization (1 2); the remaining 76% are able to undergo at least a second (degenerate) isomerization cycle (2->l->2) prior to methyl loss. 78% of metastable 1-methyl-adamantane cation radical, obtained upon direct ionization of the corresponding neutral hydrocarbon, dissociate directly, whereas the loss of methyl from the remaining 22% is preceded by an isomerization 2 ->1 ->2. 
  Reference    Z. Naturforsch. 35b, 207—211 (1980); eingegangen am 23. Oktober 1979 
  Published    1980 
  Keywords    Ion Structures, Carbocation Rearrangements, Hydrocarbon Chemistry, Mass Spectrometry, Collisional Activation 
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 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-0207.pdf 
 Identifier    ZNB-1980-35b-0207 
 Volume    35 
13Author    Heinz Egge, Uwe Murawski, Wirapong Chatranon, Fritz ZillikenRequires cookie*
 Title    eine gaschromatographisch-massenspektrometrische Analyse The Branched Chain Fatty Acids of Staphylococcus aureus, a Gas Chromato- graphic-Mass Spectrometric Analysis  
 Abstract    The fatty acid methylesters prepared by transesterification of the total lipid extract of Staphylo-coccus aureus Wood 46 were analysed by gas chromatography on thin film capillaries coated with polyphenylether (OS 138), siliconerubber (SE 30) and S.C.O.T. columns coated with Diethylene-glycoladipatepolyester (DEGA) in combination with mass spectrometry. Among the branched chain fatty acids ranging from Clt — C21, the iso-and anteiso-C15 acids are predominant. In the group of the C^ and C17 acids branching in position 9 and 10 was also found. No unsaturated branched chain fatty acids could be detected. Retention data and mass spectra of the branched chain fatty acids are presented. Die Neutrallipide, Phospholipide und Glycero-glykolipide der Staphylococcen enthalten einen gro-ßen Anteil verzweigter Fettsäuren, bei denen wo-und a/itewo-Fettsäuren vorherrschen 2 . Die quan-titative Verteilung der Lipide und der Fettsäuren ist 
  Reference    (Z. Naturforsch. 26b, 893—901 [1971]; eingegangen am 6. März 1971 revidiert am 18. Mai 1971) 
  Published    1971 
  Keywords    Staphylococcus aureus, Branched chain fatty acids, Gas chromatography, Capillary columns, Mass spectrometry 
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 TEI-XML for    default:Reihe_B/26/ZNB-1971-26b-0893.pdf 
 Identifier    ZNB-1971-26b-0893 
 Volume    26 
14Author    Gerald Zon, YoungH. ChangRequires cookie*
 Title      
 Abstract    Kinetic energy release measurements dem-onstrate that the loss of neutral HN, Et0C(0)N from the compounds investigated seems to occur by a symmetry allowed (1,1) elimination. lionized nitrenes are produced with only very low intensity. 
  Reference    (Z. Naturforsch. 33b, 129—130 [1978]; eingegangen am 10. Oktober 1977) 
  Published    1978 
  Keywords    Mass Spectrometry, Kinetic Energy Release, Orbital Symmetry, Cheletropic Reactions, Silyl Ether 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-0129_n.pdf 
 Identifier    ZNB-1978-33b-0129_n 
 Volume    33 
15Author    Bernd Richter, Helmut SchwarzRequires cookie*
 Title    Zur McLafferty-Umlagerung bei Radikalkationen von Phenylpyridylalkanonen [1] On the McLafferty Rearrangement of Ionized Phenyl Pyridyl Alkanones [1]  
 Abstract    A detailed investigation concerning the genesis of McLafferty rearrangement products from molecular ions of phenyl pyridyl alkanones reveals the following features: 1) The various products are not formed by competitive dissociations of the molecular ion. Most of the relevant fragment ions are generated from the primary McLafferty product of a hydrogen transfer to the ionized carbonyl group (M +> ->m/z 163, ion k). The ion k plays a decisive role for the generation of the abundant product ions at m/z 93 (ion g) and m/z 106 (ion s) both of which are formed by further dissociation of k. Details of the mechanisms for the decomposition of k are obtained by investigating [D]-labelled isotopomers, the analysis of low and high resolution data, the application of MIKE and CA spectra. The problem of keto/enol tautomerism between some ions, relevant in this context, is discussed and it is shown that these isomerization processes are not involved. A detaüed description is given for the syntheses of various [D]-labelled phenyl pyridyl alkanones. 
  Reference    Z. Naturforsch. 36b, 865—877 (1981); eingegangen am 16. Dezember 1980 
  Published    1981 
  Keywords    Mass Spectrometry, Hydrogen Rearrangement, Keto Enol Tautomerism, Metastable Ions, Collisional Activation 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-0865.pdf 
 Identifier    ZNB-1981-36b-0865 
 Volume    36 
16Author    Wilfried Franke, Helmut Schwarz, Chrysostomos WesdemiotisRequires cookie*
 Title    Elf stabile C5H9+-Kationen in der Gasphase. Zur dissoziativen Ionisierung von 31 isomeren C6H9Br-Verbindungen Eleven Stable CsHo 4 " Cations in the Gas Phase. On the Dissociative Ionization of 31 Isomeric CsHgBr Compounds  
 Abstract    Collisional activation mass spectrometry (CA) reveals the existence of 11 stable CsH9+ cations in the gas phase, e. g. the substituted allyl cations a, b, c, d,and e, the sub-stituted vinyl cations f, g, h, and i, the methyl cyclobutyl cation j and the cyclopentyl cation k, respectively. The ethyl substituted allyl cation a is formed via dissociative ionization of the isomeric precursors 1, 3, 4, 5, 18, 19, 20, 22, and 28 by means of various mechanistic processes, whereas the 1,3-dimethylallyl cation b is generated from both 2 (by allylic cleavage) and in part from the stereoisomeric cyclopropan derivatives 25, 26 and 27. 6"l + -gives a mixture of the vinyl cations 1 and g. From 13 and 14 the main product generated is the 1,2-dimethylallyl cation d, which is formed directly from 11 and also by quite complicated processes from 13, 14 and to a certain extent from 25, 26 and 27. The dissociative ionization of 9, 15, 16, 21, 24 and (in part) 23 give rise to the formation of the substituted vinyl cation h. Decomposition of 23"!+ • results not only in formation of h but generates also the 1,1-dimethylallyl cation e. From 291+-and 30~l +-both the methylcyclo-butyl cation j and cyclopentyl cation k are produced, whereas the isomeric precursor 28 gives mainly the substituted allyl cation a and a second, as yet, unidentified CsH^ cation. In general, it can be stated that the gas phase chemistry of cation radicals of substituted cyclopropanes is characterised by multistep-reactions, commencing with spontaneous ring opening. The so formed intermediates undergo various rearrangements (including hydrogen and alkyl shifts) prior to expulsion of Br\ Direct elimination of Br' from intact cyclopropan-like structures, followed by ring opening of the intermediate cyclopropyl cation, cannot compete with the above-mentioned multistep-sequences. 
  Reference    Z. Naturforsch. 36b, 1315—1323 (1981); eingegangen am 2. Juni 1981 
  Published    1981 
  Keywords    Isolated Carbocations, Ion Structures, Gas Phase Ion Chemistry, Mass Spectrometry, Collisional Activation 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-1315.pdf 
 Identifier    ZNB-1981-36b-1315 
 Volume    36 
17Author    Henryk Zegota++, Clemens Von SonntagRequires cookie*
 Title    Radical-Induced Dephosphorylation of Fructose Phosphates in Aqueous Solution +  
 Abstract    Oxygen free N20-saturated aqueous solutions of D-fructose-1-phosphate and D-fructose-6-phosphate were y-irradiated. Inorganic phosphate and phosphate free sugars (containing four to six carbon atoms) were identified and their G-values measured. D-Fructose-1-phosphate yields (G-values in parentheses) inorganic phosphate (1.6), hexos-2-ulose (0.12), 6-deoxy-2,5-hexodiulose (0.16), tetrulose (0.05) and 3-deoxytetrulose (0.15). D-Fructose-6-phosphate yields inorganic phosphate (1.7), hexos-5-ulose (0.1), 6-deoxy-2,5-hexodiulose (0.36), 3-deoxy-2,5-hexodiulose and 2-deoxyhexos-5-ulose (together 0.18). On treatment with alkaline phosphatase further deoxy sugars were re-cognized and in fructose-1-phosphate G(6-deoxy-2,5-hexodiulose) was increased to a G-value of 0.4. Dephosphorylation is considered to occur mainly after OH attack at C-5 and C-l in fructose-1-phosphate and at C-5 and C-6 in fructose-6-phosphate. Reaction mechanisms are discussed. 
  Reference    Z. Naturforsch. 36b, 1331—1337 (1981); received May 29 1981 
  Published    1981 
  Keywords    D-Fructo8e-l-phosphate, D-Fructose-6-phosphate, y-Irradiation, Radical Reactions, Mass Spectrometry 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-1331.pdf 
 Identifier    ZNB-1981-36b-1331 
 Volume    36 
18Author    Gemot Frenking, Jochen Schmidt, Helmut SchwarzRequires cookie*
 Title    Quantenmechanische Berechnungen zu pseudo-einstufigen (C-C)-Spaltungen bei Radikalkationen von Carbonsäuren Quantum Mechanical Calculations on Pseudo-One-Step Cleavages of Carbonic Acid Cation Radicals  
 Abstract    Extensive quantum mechanical calculations on the unrestricted MINDO/3 level reveal that for some ionised carbonic acids the energetically most feasible pathway for uni-molecular C-C cleavage cannot be described as being a one-step process. In complete agreement with experimental results the computational data are consistent with an inter-pretation of the reaction as being a two-step process, in which the reaction commences with a hydrogen migration from a CH-bond onto the ionised C = 0 group. The dissociation is completed with a radical induced C-C cleavage thus generating quite stable protonated unsaturated carbonic acids. Whereas the MINDO/3 results clearly show that the two-step process is energetically favoured over the direct C-C cleavage, this computational method fails badly in explaining the experimentally established fact that in the two-step sequence the hydrogen migration is the rate-determining step. This failure is due to the MINDO/3 inherent weakness of overestimating the stability of cyclic ions, e.g. cyclic transition states as they are formed in the course of the hydrogen migration step. Single point ab initio calculations carried out on the 4-31G level substantiate this interpretation in that the transition state for the hydrogen migration is calculated to lie substantially higher than that for the actual C-C dissociation step, but is still much lower than that calculated for a direct simple bond cleavage process of the respective cation radical. 
  Reference    Z. Naturforsch. 37b, 355—360 (1982); eingegangen am 23. Oktober 1981 
  Published    1982 
  Keywords    Potential Energy Surfaces, Carbonic Acids, Hydrogen Rearrangement, C-C Cleavage, Mass Spectrometry 
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 TEI-XML for    default:Reihe_B/37/ZNB-1982-37b-0355.pdf 
 Identifier    ZNB-1982-37b-0355 
 Volume    37 
19Author    Bernhard Ciommer, Helmut SchwarzRequires cookie*
 Title    Zur intermediären Existenz von Ethylenfluoronium-Ionen in der Gasphase On the Intermediary Existence of Gaseous Ethylen Fluoronium Ions  
 Abstract    The long-sought ethylen fluoronium ion (2) is generated as an intermediate in the dissociative ionization of l-fluoro-2-(^-methyl)phenoxy ethane (4). However, prior to collisionally induced dissociation 2 undergoes ring-opening, associated with hydrogen migration, to form 1-fluoroethyl cation (3). Other decomposition pathways of the molecular ions of 4 involve (i) direct formation of 3 via a combination of C-O-cleavage (loss of ArO -) and [1,2] hydrogen migration (18%) and (ii) complete positional loss of the a-and ß-methylene hydrogen atoms (34%). The remaining 48% of the molecular ions of 4 dissociate via anchimeric assistance of the fluorine in the elimination of ArO -, thus giving rise to the formation of 2. 
  Reference    Z. Naturforsch. 38b, 635—638 (1983); eingegangen am 23. Dezember 1982 
  Published    1983 
  Keywords    Fluoronium Ions, Neighbouring Group Participation, Gaseous Ions, Collisional Activation, Mass Spectrometry 
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 TEI-XML for    default:Reihe_B/38/ZNB-1983-38b-0635.pdf 
 Identifier    ZNB-1983-38b-0635 
 Volume    38