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  • Chemistry  (10)
  • 65F35
  • 1975-1979  (10)
  • 1
    Electronic Resource
    Electronic Resource
    Mechanismen massenspektrometrischer Fragmentierungsreaktionen, XV. Sterische und konformative Effekte in den Massenspektren von 5-tert-Butyl-1,3-cyclohexandiolen und ihren Methyläthern (1975)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 2080-2096 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mechanism of Mass Spectrometric Fragmentations, XV. Steric and Conformational Effects in the Mass Spectra of 5-tert-Butyl-1,3-cyclohexandiol and its Methyl EthersThe mass spectra of the three stereoisomers 5 - 7 of 5-tert-butyl-1,3-cyclohexanediol, of the monomethyl ethers 8 - 11, and of the dimethyl ethers 12 - 14 can be distinguished by steric controlled eliminations of H2O, CH2O and CH3OH which are typically for 1,3-cyclohexandiols. Further-more an elimination of the tert-butyl substituent as C4H8 is observed specifically in the mass spectra of 7 and its derivatives 11 and 14. - An analysis of the mass spectrometric fragmentation of deuterated derivatives shows, that the molecular ions of 5 and 6 and of their derivatives fragment exclusively from the ground conformation, while the molecular ions of 7 and its derivatives change their conformations before fragmentation. This difference in the behaviour of the molecular ions is explained on the basis of concurrent stereospecific fragmentation and changes in the conformation.
    Notes: Die Massenspektren der drei Stereoisomeren 5-7 des 5-tert-Butyl-1,3-cyclohexandiols, der Monomethyläther 8-11 und der Dimethyläther 12-14 unterscheiden sich durch die für Derivate des 1,3-Cyclohexandiols charakteristischen, sterisch kontrollierten Eliminierungsreaktionen von H2O, CH2O und CH3OH. Für 7 und seine Derivate 11 und 14 wird außerdem spezifisch die Abspaltung des tert-Butylsubstituenten als C4H8 beobachtet. - Die Analyse der massenspektrometrischen Fragmentierungen mit Hilfe deuterierter Derivate zeigt, daß die Molekül-Ionen von 5 und 6 sowie deren Derivate ausschließlich in der Grundkonformation fragmentieren, während die Molekül-Ionen von 7 und seinen Derivaten vor der Fragmentierung Konformationsänderungen erleiden. Dieses unterschiedliche Verhalten wird durch eine Konkurrenz zwischen schneller sterisch kontrollierter Fragmentierung und Konformationsänderung der Molekül-Ionen erklärt.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19751080626
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  • 2
    Electronic Resource
    Electronic Resource
    Untersuchungen zur synchronen oder zweistufigen Fragmentierung der Molekül-Ionen von 3-substituierten Tropanen (1978)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 111 (1978), S. 1962-1977 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigation of a Synchronous or Two Step Fragmention of Molecular Ions of 3-Substituted TropanesThe fragmentation of molecular ions of stereoisomeric tropanes with different substituents at position 3 has been studied. It is shown by comparison of MIKE-spectra and A(ion)-measurements, that the ions a are formed independently from the configuration at C(3). No indications of a synchronous cleavage of the bonds C(1) - C(2) and C(3) - X are obtained, but the ions a arise from a two step process, starting with α-cleavage of the molecular ions. This fragmentation is not governed by stereoelectronic requirements, thus the intensities of ions a cannot be used for a mass spectrometric identification of 3α- and 3β-tropane derivatives.
    Notes: Die Fragmentierung der Molekül-Ionen von stereoisomeren Tropanen mit verschiedenen Substituenten in Position 3 (1-11) zu den Ionen m/e = 124 durch Abspaltung des Substituenten wird untersucht. Durch Vergleich der MIKE-Spektren und durch A(Ion)-Messungen wird gezeigt, daß unabhängig von der Konfiguration an C(3) die Ionen a entstehen. Es werden keine Hinweise für eine synchrone Spaltung der C(1) - C(2)- und der C(3) - X-Bindung entsprechend einer Fragmentierung nach Grab erhalten, sondern die Ionen a entstehen in einem zweistufigen Prozeß, beginnend mit einer α-Spaltung der Molekül-Ionen. Der Zerfall unterliegt keinen stereoelektronischen Bedingungen; die Intensität der Ionen a kann daher nicht zu einer einfachen massenspektrometrischen Identifizierung von 3α- und 3β-Tropanderivaten benutzt werden.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19781110530
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  • 3
    Electronic Resource
    Electronic Resource
    Hydrogen rearrangement in molecular ions of alkyl benzenes: Mechanism and time dependence of hydrogen migrations in molecular ions of 1, 3-diphenylpropane and deuterated analoguesMechanisms of Mass Spectrometric Fragmentation Reactions XIX. Part XVIII. D. Kuck and H. F. Grützmacher, Org. Mass Spectrom. 13, 000 (1978). (1978)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1978), S. 90-102 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrogen migrations in the molecular ions of 1,3-diphenylpropane, preceding the fragmentations to [C7H7]+ and [C7H8]+ ions, have been investigated by use of deuterated derivatives. By comparing the distribution of deuterium labels in the [C7(H, D)8]+ products from metastable molecular ions with the distribution patterns calculated for various exchange models, it is shown that the H migrations occur by two processes linked by a common intermediate: (i) exchange between hydrogen isotopes at the γ-methylene group and at the ortho positions of the phenyl group: (ii) exchange between hydrogen isotopes at the ortho and orthó positions in the intermediate. In these mechanisms the eight hydrogen isotopes at both benzylic positions and both the ortho and orthó positions of 1,3-diphenylpropane participate in a mutual exchange. A statistical equipartition of the hydrogen isotopes at these eight positions is not reached in metastable molecular ions, however. The distribution pattern of [C7(H, D)8]+ ions from the deuterium labelled compounds as a function of the mean number n of exchange cycles has been calculated according to this reaction model and compared with experimental results for unstable molecular ions, generated by 70 eV and 12 eV electrons, respectively, and metastable molecular ions. Good agreement is obtained for all compounds and n = 0.4-0.8 for unstable molecular ions and n = 5-8 for metastable ions. Therefore, the hydrogen exchange in the molecular ion of 1,3-diphenylpropane is a rather slow process. These results firmly establish the isomerization reaction involving the conversion of the molecular ion of 1,3-diphenylmethane to the intermediate and hence to the molecular ion of 7-(2-phenylethyl)-5-methylene cyclohexa-1,3-diene and preceding the fragmentations. The postulated intermediate is a true one which corresponds to a s̰-complex type ion and which fragments to [C7H8]+ ions. Surprisingly, no isomerizations of the intermediate by hydrogen shifts within the protonated aromatic system (‘ring walks’) are observed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210130206
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  • 4
    Electronic Resource
    Electronic Resource
    Zum Mechanismus Massenspektrometrischer Fragmentierungsreaktionen. XVIXV. Mitteilung: siehe Lit. 1. - hydrid-Wanderungen bei der Fragmentierung von αω-Dimethoxyalkyl-Ionen (1976)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1976), S. 1168-1180 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The isomerization and fragmentation of α,ω-dimethoxyalkyl ions a (CH3OCH2(CH2)n- CH+OCH3, n = 1-6) has been investigated by deuterium labelling. It is shown that a isomerizes to ion a' by hydride transfer from the ω-CH2 group to the positive charge at the α-C-atom before elimination of methanol. Both methoxy groups are lost as methanol. The amount of isomerization can be deduced from alkene elimination from [a — CH3OH]+ ions in deuterated derivatives of a. On average at 70 eV three rearrangement steps involving hydride transfer are observed.
    Notes: Das Isomeisierungs-und Fragmentierungsverhalten von α,w-dimethoxyalkylionen a (CH3OCH2(CH2)n CH+OCH3, n = 1-6) wird mit Hilfe von Deuteriummarkierungen untersucht. Es wird gezeigt, daß vor eine Methanol-Eliminierung a durch einen Hydrid-Übertragung von der w-ständigen CH2-Gruppe auf das positive Ladungszentrum am α-C-Atom zu a' isomerisiert und bide Methoxygruppen als Methanol abgespalten werden können. An Hand der Alken-Eliminierung aus [a -CH3OH]+-Ionen in deuterierten Derivaten von A word auf den Isomerisierungsgrad geschlossen. Bei 70 eV treten danach im Mittel bis zu drei Umlagerungsschritte auf, bei denen ejweils eine Hydrid-Übertragung stattfindet.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210111108
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  • 5
    Electronic Resource
    Electronic Resource
    Substituent effects in the mass spectra of benzoyl hetarenesSee Ref. 1. (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 567-570 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of several benzoyl hetarenes, of 2-benzoyl pyridines substituted at the phenyl and pyridyl group, respectively, and of phenyl substituted 2-benzoyl pyrroles, have been studied with respect to the formation of benzoyl and hetaroyl ions. A correlation between the intensity of benzoyl ions, relative to molecular ion intensity, and the π-electron density at the substituted carbon atom of the hetarene has been observed for benzoyl hetarenes. The relative intensities of (substituted) benzoyl ions of substituted 2-benzoyl pyridines and 2-benzoyl pyrroles are not easily related to substituent constants of Hammett equations. The relative ionization energies of phenyl substituted 2-benzoyl pyridines, however, and the relative appearance energies of substituted benzoyl ions derived therefrom follow the σIP+-constant of Bentley and Johnstone and the σ+-constants of Brown, respectively.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210141011
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  • 6
    Electronic Resource
    Electronic Resource
    The activation energy of the skeletal isomerization in the radical cations of toluene and cycloheptatriene by mass spectrometry of their 2-phenylethyl derivatives (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 86-97 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Unimolecular mass spectrometric fragmentations of the molecular ions of 1,3-diphenylpropane, 1-(7-cycloheptatrienyl)-2-phenylethane and the 1-phenyl-2-tolylethanes and their [d5]phenyl analogues have been investigated by metastable ion techniques and measurements of ionization and appearance energies. By comparing the formation of [C7H7]+, [C7H8]+⋅, [C8H8]+⋅ and [C8H9]+ it is shown that the molecular ions of the four diaryl isomers do not undergo ring expansion reactions of the aromatic nuclei prior to these fragmentations. Conversely, the molecular ions of the cycloheptatrienyl isomer suffer in part a contraction of the 7-membered ring. From these results and from the measured ionization and appearance energies lower limits to the activation energies of these skeletal isomerizations have been estimated yielding Eisom+ 〉 33±5 kcal mol-1 formonoalkylbenzene, Eisom+ 〉 20 2±5 kc mol-1 for 7-alkylcycloheptatriene and Eisom+ 〉 40±5 kcal mol-1 for dialkylvbenzene positive radical ions. Upper limits can be deduced from literature evidence yielding Eisom+ 〈 45 kcal mol-1 for monoalkylbenzene and Eisom+ 〈 53 kcal 4mol-1 for dialkylbenzene positive radical ions. The activation energy thus estimated for monoalkylbenzene is in excellent agreement with the recently calculated value(s) for the toluene ion.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210140206
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  • 7
    Electronic Resource
    Electronic Resource
    Hydrogen rearrangement in molecular ions of alkyl benzenes: Appearance potentials and substituent effects on the formation of [C7H8]+ ionsMechanisms of Mass Spectrometric Fragmentation Reactions XVIII. Part XVII: H.-Fr. Grützmacher and G. Tolkien, Tetrahedron 33, 221 (1977). (1978)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1978), S. 81-89 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism of the formation of [C7H8]+ ions by hydrogen rearrangement in the molecular ions of 1-phenylpropane and 1,3-diphenylpropane has been investigated by looking at the effects of CH3O and CF3 substituents in the meta and para positions on the relative abundances of the corresponding ions and on the appearance energies. The formation of [C7H8]+ ions from 1,3-diphenylpropane is much enhanced at the expense of the formation of [C7H7]+ ions by benzylic cleavage, due to the localized activation of the migrating hydrogen atom by the γ phenyl group. A methoxy substituent in the 1,3-diphenylpropane, exerts a site-specific influence on the hydrogen rearrangement, which is much more distinct than in 1-phenylpropane and related 1-phenylalkanes, the rearrangement reaction being favoured by a meta methoxy group. The mass spectrum of 1-(3-methoxyphenyl)-3-(4-trideuteromethoxyphenyl)-propane shows that this effect is even stronger than the effect of para methoxy groups on the benzylic cleavage. From measurements of appearance potentials it is concluded that the substituent effect is not due to a stabilization of the [C7H7X]+ product ions. Whereas the [C7H7]+ ions are formed directly from molecular ions of 1-phenylpropane and 1,3-diphenylpropane, the [C7H8]+ ions arise by a two-step mechanism in which the s̰ complex type ion intermediate can either return to the molecular ion or fragment to [C7H8]+ by allylic bond cleavage. Obviously the formation of this s̰ complex type ion, is influenced by electron donating substituents in specific positions at the phenyl group. This is borne out by a calculation of the ΔHf values of the various species by thermochemical data. Thus, the relative abundances of the fragment ions are determined by an isomerization equilibrium of the molecular ions, preceding the fragmentation reaction.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210130205
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  • 8
    Electronic Resource
    Electronic Resource
    Dialkylphosphinsäureazide II (1979)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 451 (1979), S. 158-174 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dialkylphosphinic Azides. IIThe title compounds with X = O, Se, Se and R = Phenyl, Ethyl, and Methyl[2H3] were prepared and recorded by mass, vibrational and n.m.r. spectroscopy. The spectra are discussed in relation to the parent compounds [(CH3)2PS]2 and R2PXCl, which are also recorded.
    Notes: Die Dialkylphosphinsäureazide des Typs R2PXN3 wurden mit X = O, S, Se bzw. R = Phenyl, Ethyl und Methyl[2H3] dargestellt. Die Eigenschaften, Massenspektren, Schwingungsspektren und NMR-Daten werden mitgeteilt und diskutiert. Zusätzlich wurden die entsprechenden Ausgangsverbindungen [(CH3)2PS]2 und R2PXCl aufgenommen.
    Additional Material: 11 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19794510123
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  • 9
    Electronic Resource
    Electronic Resource
    DialkylphosphinsäureazideProfessor Carl Mahr zum 75. Geburtstage am 22. Dezember 1975 gewidmet. (1975)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 418 (1975), S. 247-258 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: DialkylphosphinsäureazideThe phosphonylazides of the type R2P(X)N3 with R = Me, Et and X = O, S form colourless to light yellow, not explosive, monomeric compounds. The vibrational and NMR spectra are discussed. So the bond order of the P—S bond is nearly one in opposition to the P=O double bond. Only the mass spectra of the oxo-compounds show the capture of an alkyl group.
    Notes: Die Phosphinsäureazide des Typs R2P(X)N3 mit R = Me und Et und X = O und S bilden farblose bis schwach gelbe, nicht explosive, monomere Verbindungen. Aus der Diskussion der Schwingungs- und NMR-Spektren folgt bei den Thiophosphinsäureaziden eine P—S Einfachbindung, während bei den Oxoverbindungen eine P=O Doppelbindung angenommen werden kann. Aus den Massenspektren geht hervor, daß nur die Oxoverbindungen eine Alkylgruppe einfangen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19754180308
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  • 10
    Electronic Resource
    Electronic Resource
    Darstellung und spektroskopische Untersuchungen einiger 15N-markierter Phosphorazide (1979)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 450 (1979), S. 149-164 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Spectroscopic Properties of 15N-labelled Phosphorus AzidesThe phosphorus(V)azides R2P(X)N3 and [NP(N3)2]3 were prepared using 15N-labelled alkali metal azides. From both, the vibrational and 15N-N.M.R. spectra were recorded and discussed in respect to those of the unlabelled compounds.
    Notes: Einige Phosphor(V)-azide des Typs R2P(X)N3 und [NP(N3)2]3 wurden 15N-markiert dargestellt. Die Schwingungs- und 15N-NMR-Spektren dieser Verbindungen wie auch die der Alkalimetallazide, die zur Herstellung dienten, werden mitgeteilt und mit denen der entsprechenden unmarkierten Azide verglichen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19794500119
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