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  • 1
    Electronic Resource
    Electronic Resource
    Electron donor-acceptor compounds, XXXVI. Quinones and quinhydrones of the [2.2]- and [3.3]metaparacyclophane series (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 796-813 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Elektron-Donor-Acceptor-Verbindungen, XXXVI Chinone und Chinhydrone der [2.2]- und [3.3]Metaparacyclophan-ReihenDie isomeren Chinhydrone 1 und 2 sowie das Bis(chinon) 6 der [2.2]Metaparacyclophan-Reihe wurden synthetisiert. Vorstufe dieser Verbindungen war das Tetramethoxy[2.2]metaparacyclophan 3, das über 4 und 5 dargestellt wurde. Röntgen-Strukturanalysen von 1, 3 und 6 werden im Hinblick auf die sterische Spannung dieser Moleküle und die Donor-Acceptor-Orientierung in 1 diskutiert. Charge-transfer-Absorptionen von 1 und 2 werden ebenso behandelt wie der Circulardichroismus von 1, das in Enantiomere getrennt werden konnte.  -  Auf analogem Wege wurden die isomeren Chinhydrone 13 und 14 sowie das Bis(chinon) 15 der [3.3]Metaparacyclophan-Reihe dargestellt. Der Unterschied in der sterischen Spannung zwischen den [3.3]- und [2.2]-Metaparacyclophan-Reihen wird auf der Grundlage der Röntgen-Strukturanalyse von 13 diskutiert. Charge-transfer-Absorptionen von 13 und 14 werden angegeben.
    Notes: The isomeric quinhydrones 1 and 2 as well as the bis(quinone) 6 of the [2.2]metaparacyclophane series were synthesized. Precursor of these products was the tetramethoxy[2.2]metaparacyclophane 3 which was prepared via 4 and 5. X-ray structure analyses of 1, 3 and 6 are discussed with regard to the steric strain in these molecules and the donor-acceptor orientation in 1. Charge-transfer absorptions of 1 and 2 are reported as well as circular dichroism of 1 which was separated into enantiomers.  -  Following an analogous route the isomeric quinhydrones 13 and 14 as well as the bis(quinone) 15 of the [3.3]metaparacyclophane series were prepared. The difference in steric strain of the [3.3]- in comparison to the [2.2]metaparacyclophane series is discussed on the basis of an X-ray structure analysis of 13. Charge-transfer absorptions of 13 and 14 are reported.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180238
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  • 2
    Electronic Resource
    Electronic Resource
    Proximity effects in the mass spectra of crowded bis(dialkylamino)arenes. Part IV: A tandem mass spectrometry study of fluorenodiazonine and fluorenodiazecine derivatives (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 27 (1992), S. 521-522 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210270426
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  • 3
    Electronic Resource
    Electronic Resource
    Behaviour of salts of very strong proton-sponge bases in the gas phase: Extended proximity effects and maintenance of the hydrogen bridge under soft ionization. An electron impact and liquid secondary ion mass spectrometric/collision-induced dissociation tandem mass spectrometric studyProximity Effects in the Mass Spectra of Crowded Bis(dialkylamino)arenes, Part VI. (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 490-493 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The liquid secondary ion mass spectrometry and electron impact ionization fragmentation pathways of 1,9-bis(dimethylamino)-2,8-dimethoxy-dibenzofuran (1), a new proton-sponge base with increased steric compression (buttressing) and much higher basicity (pKa = 14.3), and of its monoprotonated (2) and monodeuterated (3) salts were invetigated in a collision-induced dissociation (CID) tandem mass spectrometric study supported by unimolecular linked scans at constant B/E, CID mass-analysed ion kinetic energy spectra and accurate mass measurements. They show an ‘extended’ proximity effect, involving the stepwise participation of all the four functional groups, in addition to the ‘normal’ proximity effect involving loss of Me2NH and H·. The behaviour of 1 appears to differ in some ways from that of its protonated (2) or deuterated (3) salts. The unprecedented observation of the maintenance of the hydrogen (or deuterium) bridge under soft ionization in the salts of very strong proton-sponge bases, which show buttressing effects in solution, is strong experimental support for the conservation of these buttressing effects in the gas phase, where the protonated (or deuterated) cations of salts such as 2 (or 3) are very stable, H+ (or D+) being completely ‘sequestered.’
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210280504
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  • 4
    Electronic Resource
    Electronic Resource
    7H-benz [kl]acridin-7-ylium closed-shell ion produced from 1,8-bis(phenylamino)naphthalenes under electron impact: Tandem mass spectrometric structure elucidationProximity Effects in the Mass Spectra of Crowded N-Phenyl-substituted 1,8-Diaminonaphthalenes Part VII. (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 494-498 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Not only strongly basic aromatic amines such as ‘proton sponges’ show characteristic [M - Me2NH - H]+ peaks corresponding to cyclization to stable heterocyclic ions under electron impact. The fragmentation of the title compounds, which are weak bases, leads to [M - RNH2 - C6H5]+ heteroaromatic ions. These are the 7-phenyl-7H-benz[kl]acridine radical cation and the delocalized stable 7H-benz[kl]acridin-7-ylium ion as shown by unimolecular metastable ion spectra, collision-induced decomposition (CID) tandem mass spectrometry (MS/MS) and accurate mass measurements. The high-collision-energy CID tandem mass spectra of these ions are perfectly superimposable on those of the ions produced by the reference substance, 7-phenyl-7H-benz[kl]acridine obtained as a by-product in the Ullmann phenylation of 1,8-diaminonaphthalene. This combination of MS/MS experiments also provides strong support for the gas-phase reaction mechanism leading to the benz[kl]acridine ions and for the structures of these ions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210280505
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  • 5
    Electronic Resource
    Electronic Resource
    Reactions within and between adjacent dimethylamino groups: Collision-induced dissociation tandem mass spectrometric study of the 1,9-bis(dimethylamino)phenalenium cationProximity Effects in the Mass Spectra of Crowded Bis(dialkylamino)arenes, Part V.Dedicated to Professor Hans-Fr. Grützmacher on the occasion of his 60th birthday. (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 615-618 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron impact (EI) ionization-induced fragmentation pathways of the new 1,9-bis(dimethylamino) phenalenium cation [1]+ were investigated. The peri-dimethylamino substituents of [1]+ are incorporated in a trimethine cyanine substructure and show strong steric interactions. A mechanism is proposed for the unusual elimination of CH3N=CH2, HN(CH3)2 and (CH3)3N from [1]+ and for the accompanying cyclizations to heterocyclic ions: prior to fragmentation, the intact cation [1]+ rearranges, by reciprocal CH3 and H transfers, to new isomeric cations which decompose subsequently in a characteristic way. A wealth of consistent information on dissociation pathways and fragment structures is provided by collision-induced dissociation tandem mass spectra, collision-induced dissociation mass-analysed ion kinetic energy spectra and exact mass measurements of the salt cation and of its primary fragment ions. The liquid secondary ion mass spectrum of [1]+ is very similar to its EI mass spectrum.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210280524
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  • 6
    Electronic Resource
    Electronic Resource
    Zur Hydrid-Übertragung auf 3.4-Dehydro-toluol (1971)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 744 (1971), S. 8-14 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydride Transfer to 3,4-DehydrotolueneThe reaction of p-fluorotoluene with lithiumdiethylamide in ether produces a mixture of α-[m- and p-toluyl]-diethylamine (14m,p) and m- and p-[N,N-diethyl]-toluidine (16m and 16p); toluene is isolated as a by-product. The same reaction in the presence of furan results in the formation of 6-methyl-1,4-dihydro-naphthalene-1,4-endoxide (17). A 3,4-dehydrotoluene intermediate is quite probably involved. - In an analogous reaction with p-iodotoluene which yields toluene as a major product as well as α-[p-toluyl]-diethylamine (14p), a direct halogen substitution and a halogen-metal exchange are much more likely.
    Notes: Die Umsetzung von p-Fluor-toluol mit Lithium-diäthylamid in Äther führt zu einem Gemisch von α-[m- und p-Tolyl]-diäthylamin (14m,p) sowie m- und p-[N.N-Diäthyl]-toluidin (16m bzw. 16p); Toluol wird als Nebenprodukt isoliert. Dieselbe Reaktion ergibt in Gegenwart von Furan 6-Methyl-1.4-dihydro-naphthalin-endoxid-(1.4) (17). Eine 3.4-Dehydro-toluol-Zwischenstufe läßt sich hier mit Sicherheit nachweisen. - Bei der analogen Reaktion mit p-Jodtoluol, die Toluol als Hauptprodukt und außerdem α-[p-Tolyl]-diäthylamin (14p) liefert, lassen sich hingegen eine direkte Halogen-Substitution und ein Halogen/Metall-Austausch wahrscheinlich machen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.19717440103
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  • 7
    Electronic Resource
    Electronic Resource
    Electron impact and chemical ionization mass spectra of bis(methoxycarbonyl) [2.2](2,5)pyridinophanes. Formation of quinolizinium ions under electron impact (1986)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 21 (1986), S. 367-370 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For four isomeric bis(methoxycarbonyl)[2.2](2,5)pyridinophanes differing only in the mutual orientation of the two nicotinic ester units, electron impact mass spectra were measured. The fragmentations observed distinguish surprisingly well between the isomers, depending on the transannular substitution pattern. Of special interest is that for one isomer the otherwise unimportant ion at m/z 298 is found as base peak. This ion is formed by expulsion of HCN from the molecular ion, transannular cycloaddition and aromatization to a stable quinolizinium ion. Fragmentation pathways of the isomers are compared, and chemical ionization and negative ion chemical ionization mass spectra are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210210612
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  • 8
    Electronic Resource
    Electronic Resource
    Proximity effects in the mass spectra of crowded bis(dimethylamino)arenes: Part II - Rearrangements of the molecular radical cations of ‘proton sponges’ by reciprocal methyl/hydrogen transfer (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 24 (1989), S. 367-372 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The EI induced fragmentation pathways of 4,5-bis(dimethylamino)fluorene, 4-(d6-dimethylamino)-5-(dimethylamino)fluorene, 4,5-bis(d6-dimethylamino)fluorene, 4-(dimethylamino)-5-methylaminofluorene, 4,5-bis-(methylamino)fluorene, 4-amino-5-methylaminofluorene, 1,8-bis(dimethylamino)naphthalene, 1,8-bis(d6-dimethyl-amino)-naphthalene and 1,8-bis(dimethylamino)-2,7-dimethoxynaphthalene were investigated. A mechanism is pro-posed for the surprising elimination of CH3—NH2 from the molecular ion, followed by loss of C2H5·, C2H4 and CH3CN and for the accompanying cyclizations to stable heterocyclic ions: prior to fragmentation the molecular radical ion rearranges to new, distonic radical ions by reciprocal H and CH3 transfers between the adjacent dimethylamino groups. Each of these new, isomeric molecular ions decomposes subsequently in a characteristic way.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210240602
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