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  • 11
    Electronic Resource
    Electronic Resource
    Spectres de Masse de Derives de l'Atractyloside. Determination du Nombre de Substituants par Combinaison d'Acetylation et de Silylation (1974)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 8 (1974), S. 89-94 
    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: Different transformations of the functions fixed on a heterocyclic molecule were made. It is thus possible to quickly determine the number of functions of each type present in the molecule: e.g. (i) all the functions are silylated and (ii) the alcohols are acetylated whilst the sulfates and acids are silylated. Mass spectra of atractylate, apoatractylate and gummiferine have been studied and the substituents are counted and enumerated.
    Notes: En créant des dérivés différents suivant la fonction que l'on transforme, il est possible de dénombrer rapidement chacune de ces fonctions sur une molécule complexe du type hétéroside. Silylation de toutes les fonctions dans un premier temps suivie de l'acétylation des fonctions alcools et de la silylation des sulfates et acides dans un second temps. Des molécules d'atractylate, d'apoa-tractylate et de gummiférine ont été étudiées de cette façon.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210080112
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  • 12
    Electronic Resource
    Electronic Resource
    Spectres de masse des anomeres pyranniques et furanniques de la thymidine, de leurs acetates et des bromohydrines correspondantes (1973)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1973), S. 543-554 
    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 mass spectra of furanic and pyranic anomers of thymidine as well as those of acetates and bromohydrines of these four molecules are studied and compared. The stability of molecular ions is correlated with the chemical stability of these copmpounds. Molecular ions of β forms are more stable than those of α forms. The instability of the bromohydrines molecular ions is such that they are only observed for β furanic anomers.The eliminmation of the ·CH2OH or ·CH2OAc radical is noterd only for the furanic compound. The cleavage of CH2O in the β furanic substances is correleated with the steric vicinity of the base and the sugar 5′ hydroxide. The ions[BH — Ch=CH2]+ and those resulting from this rearrangement and cleavage of sugar moiety, are enhanced in the case of furanic forms.After rupture of the N-glycosidic bon, the [B + H]+· and [B + 2H]+ ions resulting from the base and [S]+ are related to the molecular stereochemistry. The eliminationof one water molecular(or acetic acid) is easier in a sixs membered ring(pyranic). The concerted elimination of two water molecules (or acetic acid), more important in the furanic form, enables us to establish a ring cleavage mechanism which gives an ion with a conjugated aliphaticf structure; the pyranic form gives an aromatic cyclic ion in two steps.
    Notes: L'étude du spectre de masse des anomères pyranniques et furanniques de la thymidine, de leurs acétates et des bromohyrines correspondantes apporte des informations, intéressantes pour l'analyse de al configuration anomérique de ce type de composés, décisives pour la dimension de l'hétérocycle oxygéné.La stabilité des ions molécularies va de pair avec la stabilité chimique de ces molécules: les ions moléculaires des formes β sont plus ceux des formes α. L'instabilité des ions moléculaires des bromohydrines est telle qu'ils ne sont détectables que pour la forme β furannique.L'elimination du radical CH2OH ou CH2OAc est caractéristique de la forme furannique. L'élimination de CH2O dans la forme β furannique est due à la proximité stérique de la base et de l'hydroxyle en 5′ du sucre. Les ions de rearrangement [BH — CH—CH2]+ et dérivés proviennent d'und rupture du sucre favorisée dans la forme furannique.Après cassure de la liaison glycosidique, les ions [B + H]+· et [B + 2H]+ formés sur la base, et [S]+ sont sensibles à la stéréochimie de la molécule. L'´elimination d'une molécule d'eau (ou d'acide ac´etique) est mormalement plus facile dans un cycle à 6 chaînons (pyrannique).L'élimination simultance de 2 molécules d'eau ou d'acide acétique, prépondérante dans la forme furannique, nous a conduit à conduit à admettre und rupture du cycle pour former un ion à sttructure aliphatique conjuguée; la forme pyrannique donne un ion cyclique aromatique, en 2 étapes.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210070505
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  • 13
    Electronic Resource
    Electronic Resource
    Fragmentation de Quelques Hydrazines, Tétrahydrocinnolines et Pyrazolidines sous I'Impact Electronique (1977)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1977), S. 717-723 
    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 mass spectra of various hydrazines, tetrahydrocinnolines and pyrazolidines, prepared by the condensation of a diazenium cation or its conjugated base with olefins, are discussed. The main fragmentation mode of trisubstituted hydrazines corresponds to a retroaddition process which produces the diazenium cation and the olefin. Another fragmentation mode involves breaking of the N—N bond which is due to a charge localization in the phenyl ring the latter being substituted on a nitrogen atom in all the hydrazines studied. This N—N bond split is dominant in the fragmentation of tetrahydrocinnolies. On the other hand, its does not appear in the spectra of pyrazolidines. The latter mainly undergo a dipolar-1, 3 retroaddition-like process giving the protonated form of the azomethine imine used in thier synthesis.
    Notes: Les spectres de masse de diverses hydrazines, tétrahydrocinnolines et pyrazolidines, issues de la condensation d'une cation diazénium ou de sa base conjguée sur des oléfines sont discutés. Le mode de fragmentation principal des hydrazines trisubstituées correspond à un processus de rétroaddition libérant le cation diazénium et l'oléfine. On Observe aussi une rupture de la liaison N—N qui peut s'expliquer par une délocalisation de la charge de l'ion moléculaire sur les noyaux phényles que toutes les hydrazines considérées protent sur l'un de leurs atomes d'azote. Cette rupture de la liaison N—N est la fragmentation dominante dans le cas des tétrahydrocinnolines. Par contre, elle n'est pas observable chez les pyrazolidines. Ces dernières subissent principalement une fragmentation voisine d'une rétroaddition de type dipolaire-1,3. Celle-ci libère le cation diazénium dont la base conjuguée qui est une imine d'azométhine a été utilisée dans la synthèse.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210121202
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  • 14
    Electronic Resource
    Electronic Resource
    Fast atom bombardment mass spectra of protected deoxyribodinucleotides (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 19 (1984), S. 585-588 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210191113
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  • 15
    Electronic Resource
    Electronic Resource
    Matrix effects in fast atom bombardment mass spectrometry of cationic iridium(III) and rhodium(III) coordination complexes (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1985), S. 463-466 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast atom bombardment mass spectra of cationic iridium(III) and rhodium(III) coordination complexes (M+Cl2L2, X-; where the ligand L is a dinitrogenous aromatic system) have been obtained with thioglycerol, glycerol or tetraglyme as a matrix. Two kinds of reactions, initiated by particle bombardment, have been discovered between these complexes and the matrix. First, with thioglycerol one or two chlorine atoms are substituted by a thioglycerol radical, more rapidly for rhodium compounds; secondly, when the ligand L possesses a diazo function, this function is hydrogenated depending on the ability of the matrix to generate hydrogen radicals by bombardment.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210200707
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  • 16
    Electronic Resource
    Electronic Resource
    Mass spectra of aliphatic dicarboxylic acids and their dimethyl esters: Cyclic structures for the [M - H2O]+· ions from the diacids and [M - MeOH]+· ions from the dimethyl esters (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 23 (1988), S. 723-728 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl 2-oxocycIoalkane carboxylate structures are proposed lor the [M - MeOH]+· ions from dimethyl adipate, pimelate, suberate and azelate. This proposal is based on a comparison of the metastable ion mass spectra and the kinetic energy releases for the major fragmentation reaction of these species with the same data for the molecular ions of authentic cyclic β-keto esters. The mass spectra of α,α,α′,α′-d4-pimelic acid and its dimethyl ester indicate that the α-hydrogens are involved only to a minor extent in the formation of [M - ROH]+· and [M - 2ROH]+· ions, while these α-hydrogens are involved almost exclusively in the loss of ROH from the [M - RO·]+ ions (R = H or CH3). The molecules XCO(CH2)7COOMe (X = OH, Cl) form abundant ions in their mass spectra with the same structure as the [M - 2MeOH]+· ions from dimethyl azelate.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210231009
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  • 17
    Electronic Resource
    Electronic Resource
    Fragmentations de quelques derives thiophosphores sous l'impact electronique. I - migration de groupes phenyles et methyles dans les derives du diphenylthiophosphorane (1975)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1975), S. 770-780 
    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 localised radical or charge site formalism in substituted diphenylthionophosphoranes Ph2P(S)R (R = phenyl, methyl, benzyl, methylthiomethyl, phenacyl, amino and N-benzylideneamino) allowed the elucidation of their electron-impact-induced fragmentation patterns. The atomic composition of the fragments was determined by precise mass measurements. Fragmentation patterns are proposed which are consistent with the presence of several metastable peaks. These patterns for phenyl, methyl, phenacyl and amino diphenylthionophosphoranes are characterised by a significant migration of the phenyl and methyl group from phosphorus to sulphur. Different patterns are favoured in benzyl, methylthiomethyl and N-benzylideneamino diphenylthionophosphoranes by elimination of very stable species.
    Notes: La localisation de la charge d'ionisation dans les diphénylthiophosphoranes substituspar des groupes phényle, méthyle, benzyle, méthylthiométhyle, phénacyle, amino et N-benzylidèneé amino a permis d'élucider leurs réctions de fragmentation sous l'impact électronique. La composition atomique des divers fragments été déterminée par la mesure précise de leur masse. Ces mécanismes de fragmentation sont confirmés par la présence de nombreux pics d'ions métastables. Les principales fragmentations des composés par la présence de nombreux pics d'ions métastables. Les principales fragmentations des composés phénacyl et aminodiphénylthiophosphoranes s'expliquent par la migration importante de groupes phényles et méthyle du phosphore vers le soufre. Dans les composés benzyl, méthylthiométhyl et N-benzylidéneamino, l'élimination d'espéces neutres très stables (respectivement le radical benzyle, le thioformaldéhyde et le benzonitrile) favorise d'autres mécanismes de fragmentation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210100913
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  • 18
    Electronic Resource
    Electronic Resource
    Comparison of EI, FAB and DCI (electron capture mode) mass spectra of hydrolytically labile dihalogenotitanium (IV) porphyrins (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1987), S. 45-48 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210220112
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  • 19
    Electronic Resource
    Electronic Resource
    Fragmentations de quelques Derives thiophosphores sous L'impact electronique. II - Migration de groupes phenyles et d'atomes de soufre dans quelques derives dithiophosphores (1975)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1975), S. 1021-1031 
    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: Some compounds having two diphenylphosphino or diphenylthiophosphoranyl groups give rise by electron-impact-induced fragmentation to varied migrations of phenyl groups or of sulfur atoms. According to the compound, the phenyl moves by migration from one phosphorous to the other, or to the sulfur which is bound to the other phosphorous. Migration of the phenyl from the phosphorous towards the carbon arises when this is strongly electrophilic. The thiophosphorous compounds also give rise to sulfur atom migrations from the phosphorous to the carbon, or to the double bond placed in α of phosphorous atom.
    Notes: Les fragmentations de quelques dérivés contenant soit deux groupes diphénylphoshino, soit deux groupes diphénylthiophosphoranyles donnent lieu à diverses migrations de groupes phényles et d'atomes de soufre. Les phényles migrent, suivant le composé, soit d'un phosphore à l'autre, soit d'un phosphore vers le soufre lié à l'autre phosphore. Des migrations d'un phényle du Phosphore vers le carbone ont lieu lorsque ce dernier est fortement électrophile. Dans les composés thiophosphorés, on observe des migrations d'atomes de soufre du phosphore vers le carbone ou la double liaison situé en α de l'atome de phosphore.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210101112
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  • 20
    Electronic Resource
    Electronic Resource
    Fast atom bombardment mass spectrometry of some alkoxv- and chloro-silanes (1991)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 26 (1991), S. 81-84 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The positive and negative FAB mass spectra of a series of alkoxy- and chloro-silanes Xm(CH3)3-mSi(CH2)nR [m = 1 or 3, n = 3, 10 or 17, X = Cl or OMe or OEt, R = Me, NH2, glycidoxy, COOMe, NHCO(CH2)7COOMe or NHCO(CH2)10CH2OAc] were recorded in NBA and NPOE matrices. The chlorosilanes underwent rapid hydrolysis into silanols which condense to form siloxanes, the process being complete in NBA and partial in NPOE, yielding siloxane-based fragment ions in the positive spectra and silyloxyanions in the negative spectra. The alkoxysilanes were more resistant to hydrolysis, affording abundant [MH - HX]+ ions (X = OMe or OEt) in their positive FAB spectra and moderate to high intensity [M - H]- ions in the negative mode, the latter undergoing characteristic sequential loss of C2H4, EtOH and C2H4. Significant variations were observed in the positive spectra of all the silanes with change of matrix.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210260206
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