Massenspektrometrische Untersuchungen an Azoverbindungen. II—Ermittlung thermodynamischer Größen

The Appearance potentials of azo compounds and their characteristic fragments have been measured. Using these values and the calculated values for the heat of formation of the molecules the heats of formation of molecular ions and fragment ions and the ionization potentials of the latter have been determined. From the dissociation energies it has been concluded that the azo compounds decompose via a two-step pathway.     

Massenspektrometrische Untersuchungen an 1.1-Difluorcyclopropanen

Mass spectra and fragmentation patterns of several substituted 1,1-difluorocyclopropanes have been investigated. Trends in fragmentation probabilities of different difluorocyclopropanes seem to be related qualitatively to well known empirical substituent effects.     

Massenspektrometrische Untersuchungen an einigen Übergangsmetallcarbonyl-cyclopentadieniden

Photographically recorded high-resolution mass-spectra of the dimeric cyclopentadienyl metal carbonyls of Fe, Ni and Mo and of the trinuclear (C₅H₅)₃Ni₃(CO)₂ show distinct ion-molecule associates and fragments of associates. Several of the carbonyl containing fragment ions exhibit structural dependence to some degree. Due to experimental limitations, ionisation efficiency curves allow only a rough estimation of the appearance-potentials.     

Massenspektrometrische Untersuchungen an Oxidhalogeniden des zweiwertigen Germaniums

Mass Spectrometric Investigations of the Oxidehalides of Divalent Germanium Mass spectrometric investigations have shown the existence of gaseous oxidehalides of divalent germanium Ge₂OX₂ (X = F, Cl, Br) in the vapor phase above a solid Ge_s/GeO_2,s (1:1 Moles) + NaX_s (excess). The heats of formation of these compounds have been determined.     

Massenspektrometrische Untersuchungen von Terpenen

Zusammenfassung Die Massenspektren von 9 Monoterpen-aldehyden und -ketonen (Isomenthon, cis- und trans-Caranon-(3), Isopiperitenon, Carvon, Eucarvon, Verbenon, Perilla-aldehyd und Myrtenal) wurden ausgewertet und für die Zwecke der qualitativen Terpenanalyse durch Zahlenwerte der Intensitäten der jeweils 10 häufigsten Ionen charakterisiert. Sie unterscheiden sich alle deutlich voneinander; selbst die stereoisomeren Caranone-(3) lassen sich aufgrund von Intensitätsverhältnissen charakteristischer Fragment-Ionen eindeutig identifizieren. Aus der Untersuchung der metastabilen Ionen ergaben sich Hinweise auf den Mechanismus der lonenfragmentierung. Die Verwendung von Ionisierungs- und Auftrittspotentialdaten für die Strukturaufklärung wird diskutiert.

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Summary The mass spectra of 9 monoterpene-aldehydes and -ketones (isomenthone, eis- and trans-caranone-(3), isopiperitenone, carvone, eucarvone, verbenone, perillaldehyde and myrtenal) are evaluated and for purposes of qualitative terpene analysis each is characterized by numerical values of the intensities of the 10 most abundant ions. All mass spectra exhibit significant differences: even the stereoisomeric caranones-(3) can be identified unambiguously by the abundance ratios of characteristic fragment ions. Features of the ion fragmentation mechanisms could be derived from metastable ion analysis. The use of ionization- and appearancepotential data for structure elucidation is discussed.

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Herrn Prof. Dr. G. O. Schenck danken wir für die wohlwollende Förderung dieser Arbeit und für einige wichtige Hinweise. Den Herren Dr. G. Schaden und Dr. G. Steffan danken wir für anregende Diskussionen.     

Massenspektrometrische Untersuchungen von Terpenen

Zusammenfassung Die Massenspektren von acht Caranolen (trans-Caran-trans-2-ol, cis-Caran-trans-2-ol, trans-Caran-trans-3-ol, cis-Caran-trans-3-ol, trans-Caran-cis-3-ol, cis-Caran-cis-3-ol, Caran-trans-4-ol und Caran-cis-4-ol) wurden untersucht. Aus der Zuordnung der metastabilen Ionen ergaben sich Hinweise auf den Mechanismus der Fragmentierung von Caranol-Ionen. Ein Vergleich der Massenspektren zeigte, da\ die quantitativen Unterschiede in den relativen IntensitÄten sowohl eine qualitative Identifizierung als auch eine quantitative Analyse von Caranolgemischen erlauben.

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Summary The mass spectra of eight caranols (trans-carane-trans-2-ol, cis-carane-trans-2-ol, trans-carane-trans-3-ol, cis-carane-trans-3-ol, trans-carane-cis-3-ol, cis-carane-cis-3-ol, carane-trans-4-ol, and carane-cis-4-ol) were investigated. Certain aspects of the caranol ion fragmentation mechanism could be derived from an analysis of metastable ions. It is concluded that identification of caranols as well as quantitative analysis of caranol mixtures can be based solely on quantitative evaluation of abundance ratios.

     

Massenspektrometrische Untersuchungen von Terpenen

The mass spectra of 5 groups of altogether 27 monoterpenes (2 caranes, 5 carenes, 4 menthanes, 8 menthenes, and 8 menthadienes) were studied and individual spectra were found in most cases to be sufficiently distinct for purposes of identification. Only the mass spectra of the 4 menthanes (the cisand trans-p- and m-menthanes) differed so little from each other as to make mass-spectral identification cumbersome. From an investigation of metastable transitions breakdown patterns were derived for each group of compounds.     

Massenspektrometrische Untersuchungen an Phosphins?ureestern von Monohydroxysteroiden

Ohne Zusammenfassung

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Mass spectrometric investigations on phosphinic esters of monohydroxy steroids

     

Massenspektrometrische Untersuchungen zu Dyotropen Umlagerungen

The electron impact induced cleavage of the oxygen-carbon (or oxygen-silicon) bond is accompanied by an intramolecular migration of the silyl function onto the oxygen. Details of the mechanism formally correspond with a dyotropic rearrangement.     

Massenspektrometrische Untersuchungen an Heterocyclen—V Fragmentierungsverhalten Einiger Purine

The mass spectra of 9 purines are discussed. The xanthine purines eliminate HNCO and CO consecutively, whereas 3-methylhypoxanthine loses HCN and CO. In the case of 3-methylxanthine an ion is formed whose stabilization by rearrangement is discussed. The fragmentation pattern of 3-methyl-2-thioxanthine and 3-methyl-thiohypoxanthine is different from that of the corresponding oxygen analogues. 6-Methyl-mercaptopurine and 6-methoxypurine eliminate HCS· or HCO· respectively. For the latter reaction a mechanism is suggested.     

Massenspektrometrische Untersuchungen einiger Catenane und Makrocyclen

The mass spectra of the catenanes functionalized in one ring by β-phenylethylaza-, aza-, acetylaza-, trideuteroacetylaza- and trifluoroacetylaza groups respectively, are compared with the spectra of correspondingly substituted macrocyclic and long chain compounds. The mass spectra of most of the catenanes investigated are distinguished by a dominant fragmentation process, which isinitiated by the interannular transfer of ahydrogen atom to the functional group. Fragmentations caused by initial rupture of one of the macrocycles are much less favoured. Apart from H-transfer, no interannular reactions could be detected. In the presence of a β-phenylethylaza substituent, the loss of the benzyl radical is so fast, however, that no fragmentation initiated by H-transfer can be detected. The comparison of the spectra of the open chain compounds with the macrocyclic and catenane compounds suggests that significant solvation of these functional groups by long aliphatic chains does not exist.     

Massenspektrometrische Untersuchungen einfacher und gemischter Phosphortrihalogenide

Zusammenfassung Die Massenspektren von Gemischen aus PCl₃, PBr₃ und PJ₃ zeigen die Molekülionen aller durch Halogenaustausch möglichen Phosphortrihalogenide. Auftrittspotentialmessungen lieferten die Bildungsenthalpien H _B (PCl₂Br) _g =–274±10kJ/mol und H _B (PClBr₂) _g =–212±10kJ/mol. Die Ionisierungsenergien der Phosphortrihalogenide, die Cl, Br, J enthalten, stehen in enger Beziehung zur durchschnittlichen Elektronegativität der Halogenatome. Wie stoßinduzierte Zerfälle ergaben, ist in den Phosphorhalogenidionen die P–Br-Bindung schwächer als die P–Cl-Bindung.

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Mass spectrometric investigations of phosphorus trihalides and mixed phosphorus trihalides

The mass spectra of mixtures of PCl₃, PBr₃, and PI₃ contain molecular ions of all phosphorus trihalides, which are possible by halogen exchange. Appearance potential measurements gave the heats of formation H _B (PCl₂Br) _g =–274±10kJ/mol and H _B (PClBr₂) _g =–212±10kJ/mol. The ionization energies of Cl, Br, I containing phosphorus trihalides are closely related to the average electronegativity of the halogen atoms. Collision induced fragmentations showed for ions, that P–Br bonding is weaker than P–Cl bonding.

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Teil der DissertationK. Varmuza, Massenspektrometrische Untersuchungen an einigen Phosphortrihalogeniden, Techn. Hochschule Wien, 1970.     

Massenspektrometrische Untersuchungen von Naturprodukten; Cardenolide

The mass spectrometry of cardenolides is briefly reviewed. Recent developments in the characterization of the cardiac glycosides by a combination of electron impact and field ionization methods are discussed, with emphasis on the information obtained regarding the sequence of monosaccharide residues in the case of oligosaccharide glycosides. Recent efforts to understand the detailed fragmentation behaviour of cardenolide aglycones in terms of their structure and substitution pattern are also discussed.     

Massenspektrometrische Untersuchungen an einigen Halogeniden der 5. Haupt- und Nebengruppe

The mass spectra of fifth group halids and some of their substitution products have been studied. Fragmentation processes, charge distributions as well as relative stabilities of fragment ions and double-charged ions are discussed. Appearance potentials have been measured and discussed, with reference to decomposition reactions and abundance considerations of fragment ions. In some cases polymeric ions were found in mass spectra.     

Massenspektrometrische Untersuchungen an Heterocyclen—IV: Zur Wasserstoffabspaltung aus Xanthen und Thioxanthen

The structure of the [M — 1] ions of thioxanthene (I) and xanthene (II) is investigated by means of the 9,9-dideuteroderivatives (Ia and Ia). The formation of an [M — 1]ion from Ia and IIa shows that beside a simple dissociation reaction a rearrangement to a tropylium ion is involved. A further rearrangements of this type occurs in the frgmentation of thioxanthene-S,S-dioxide (III).     

Massenspektrometrische Untersuchungen von PhthalocyaninenPc—MeX n

PhthalocyaninesPc?Me(III)X andPc?Me(V)X ₃ were obtained by reacting anhydrous metal halides with phthalodinitrile and di-lithium-phthalocyanine, resp. A phthalocyanine containing niobium(V) was prepared for the first time. Mass spectrometric investigation of the products formed show the molecular ion in the case of chloro-aluminum-, chloro-indium- and tribromo-niobium-phthalocyanine. The mass spectra of chloro-scandium-, chloro-yttrium- and tribromo-tantalum-phthalocyanine showed neither peaks of the molecular mass nor metal containing fragments of the phthalocyanine structure. Mass spectrometric results seem to depend critically on the purity of the compounds employed.     

Massenspektrometrische Untersuchungen von Isomeren Stickstoffverbindungen des Dibenzofurans

The mass spectra and the fragmentation patterns of amino-, acetamino- and nitrodibenzo-furan isomers have been investigated. Significant differences between the particular isomers are observed which are partly due to intramolecular hydrogen bond bridges, ortho effect or resonance stabilisation.     

Massenspektrometrische Untersuchungen an Silberhalogeniden. 3. Mitt. AgBr und AgJ

Ohne Zusammenfassung