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  • 1
    Electronic Resource
    Electronic Resource
    Characterisation of organoboron ligands by electrospray mass spectrometry using anhydrous solvent application (1994)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 29 (1994), S. 806-807 
    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.1210291212
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  • 2
    Electronic Resource
    Electronic Resource
    Collision-induced dissociation and charge-reversal processes of isomeric C6H4X- (X = F, Cl and Br) anions (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 749-756 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The NH2- ion reacts with fluoro- and chlorobenzene in the cell of a Fourier-transform ion cyclotron resonance instrument only by proton abstraction, whereas the reaction with bromobenzene also yields Br- ions. The deprotonation of these halogen-substituted benzenes occurs the 2-, 3- or 4-positions as revealed by deuterium labelling in combination with high kinetic energy (8keV) collision-induced dissociation (CID) experiments performed with a double-focusing quadrupole hybrid mass spectrometer. The 2-fluoro- and 3- fluorophenyl anions eliminate HF following collision with an oxygen molecule. By contrast, the collisions between 4-fluorophenyl anions and O2 do not yield detectable amounts of negatively charged fragment ions owing to the exclusive occurrence of electrom detachment. Electron detachment is also the only process observed in the 8 keV CID experiments with chlorophenyl anions and 3- and 4-bromophenyl anions, whereas the ion formed by proton abstraction from the 2-position in bromobenzene dissociates to Br- and 1,2-dehydrobenzene. The 8 keV collision-induced charge-reversal spectra of the anions formed by proton abstraction from the 2-, 3- or 4-positions in a given halogen-substituted benzene are virtually identical, indicating that this method does not provide insight into the position of the charge with respect to the halogen atom in the substituted phenyl anions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290070814
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  • 3
    Electronic Resource
    Electronic Resource
    Unimolecular reaction of the (H3CO)3C+ cation (1995)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 1185-1188 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: From metastable ion studies, Fourier transform ion cyclotron resonance experiments and semi-empirical calculations, the unimolecular reaction of the (H3CO)3C+ cation 1 is discussed. The first step of the reaction is an irreversible, 1,3-CH3+ transfer giving the H3COC(O)O(CH3)2+ ion, 2. This ion either cleaves or isomerizes into the ion-neutral complex [H3COCO+, CH3OCH3], 3. Since the H3COCO+ cation is a very good CH3+ donor, a CH+3 transfgr then occurs within the complex, 3, to yield the predominant fragment (CH3)3O+.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290091220
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  • 4
    Electronic Resource
    Electronic Resource
    A regiospecific cycloaddition: Successive reactions of ·CH2CH2OH+2 with CH2OContribution from the 2nd European FTMS Workshop, Antwerp, Belgium, September 1993. (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 53-55 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Four dominant reactions can be observed when the β-distonic ion ·CH2CH2OH+2 reacts in the cell of a Fourier-transform ion cyclotron resonance spectrometer with a number of neutral molecules: protonation of the neutral molecule, ethylene radical-cation transfer, hydride abstraction from the neutral molecule, and charge exchange. Among the ethylene transfer reactions, which can lead to a variety of other distonic ions, we have throroughly studied the reaction with formaldehyde. The reaction of a first molecule of CH2O yields ·CH2CH2OCH+2. The addition of a second one leads to 1,3-dioxane which stabilizes by H· loss. This latter reaction is regiospecific.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080110
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  • 5
    Electronic Resource
    Electronic Resource
    Isomerization reaction of [C6H6 C4H9+] π complexes (1991)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 5 (1991), S. 415-420 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Metastable protonated butylbenzenes have been studied by extensive labelling and kinetic energy release measurements. Protonated s-butylbenzene isomerizes by 1-2 hydrogen shift to the π complex [C6H6 S—C4H9+], and the S—C4H9+ cation rearranges to t-C4H9+. The interconversion between [C6H6 S—C4H9+] and [C6H7+ C4H8] ion/neutral complexes is demonstrated. Protonated t-butylbenzene reacts without hydrogen exchange to give t-C4H9+, while protonated n-butylbenzene isomerizes to s-butylbenzene prior to dissociation. Protonated iso-butylbenzene isomerizes to protonated t-butylbenzene and to protonated s-butylbenzene. In the 2nd field-free region, the dissociation of this last form predominates.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290050908
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  • 6
    Electronic Resource
    Electronic Resource
    Quantitative analysis of cytokinins by electrospray tandem mass spectrometry (1995)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 948-953 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A methodology was developed for the analysis of cytokinins from plant tissue using electrospray tandem mass spectrometry in combination with HPLC. A detection limit of 1 pmol zeatin-riboside injected on-column was achieved under multiple reaction monitoring conditions. Linearity was observed within a concentration range of 1-100 pmol injected on-column. In view of the analysis of a considerable amount of samples, the chromatographic conditions were selected which were a compromise between speed of analysis and resolution. This approach, in combination with multiple reaction monitoring, allowed the analysis of up to 150 samples a day, and quantitation of 16 different cytokinins per sample.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290091016
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  • 7
    Electronic Resource
    Electronic Resource
    Stéréochimie en série aziridine: VIPartie V: Réf. 1. - Etude en Résonance Magnétique Nucléaire d'alcools aziridiniques primaires (configuration à l'azote, isoméries de rotation) (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 35-42 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The PMR spectra of six primary aziridinyl carbinols are studied over a temperature range of -30°C to +100°C. Nitrogen configuration is determined. When the inversion process is effective, kinetic parameters are evaluated. Rotational isomerism about the ‘ring—CH2OH’ bond is studied from vicinal coupling constants associated with the two diastereotopic protons on the —CH2OH group. From the J(HOCH) coupling constant (in CCL4) rotamer populations of the hydroxyl group are determined in some cases and the overall conformational distribution can be established.
    Notes: Six alcools primaires aziridiniques diversement substitués sont étudiés en résonance magnétique nucléaire, à différentes températures. La configuration à l'azote est établie; lorsque l'inversion est effectivement observée, les paramètres cinétiques associés au phénomène sont déterminés. L'isomérie de rotation autour de la liaison cycle-carbone porteur de l'hydroxyle est étudiée à partir des deux constantes de couplage vicinales correspondant aux deux protons diastéréotopiques du groupement hydroxyméthyle. La rotation de l'hydroxyle est également abordée au moyen du couplage J(HOCH) déterminé dans CCl4 pour certains termes. Une description globale des conformations peut être alors établie.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270060110
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  • 8
    Electronic Resource
    Electronic Resource
    Recherches par resonance magnetique nucleaire sur les rotations empechees - IV: Determination des parametres d'activation associes a l'interconversion des isomeres de rotation autour de la liaison —C—C— dans la serie des composes carbonyles vinyliques β-amines (1970)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 2 (1970), S. 539-542 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Restricted rotation around the C—C bond in the O=C—C=C—N system is responsible of the s-cis and s-trans conformers as shown by the NMR spectra of vinylogous amides (CH3)2N—CH=CH—CO—R. Substituent effect (nature of R) is discussed in terms of conformational equilibrium. Theoretical line shapes have been computed and fit reasonably well with the experimental spectra; activation functions were also derived.
    Notes: L'effet de la nature du substituant R sur l'équilibre conformationnel s-cis-s-trans est examiné dans la série (CH3)2N—CH=CH—CO—R. L'utilisation d'un programme de calcul des courbes théoriques de l'échange permet la détermination des paramètres d'activation ΔH* et ΔS*.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270020603
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  • 9
    Electronic Resource
    Electronic Resource
    Stereochimie en Serie Aziridine - IIIMémoires précédents: Réf. 1. Etude de l'Isomérie de Rotation d'un Aldéhyde Aziridinique (1972)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. 703-707 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: From the ASIS effect on chemical shifts and from solvent and temperature dependence of the vicinal spin-spin coupling constant of 1-tertiobutyl 2-formyl aziridine, the following conclusion is reached: the less polar rotamer is the s-trans rotamer, which is of lower energy than the s-cis rotamer.
    Notes: L'étude de l'isomérie de rotation de la tertiobutyl-1 formyl-2 aziridine est abordée en RMN par examen de l'effet ASIS sur les déplacements chimiques, par examen de l'effet de solvant sur la constante de couplage du proton aldéhydique, enfin par étude de l'effet de la température sur ce couplage. L'isomère s-trans qui est le moins polaire est largement privilégié.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270040510
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  • 10
    Electronic Resource
    Electronic Resource
    Spectrometrie de Masse des Epoxydes Phenyles - IIIère partie voir Réf. 1. (1974)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 8 (1974), S. 201-216 
    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 fragmentation of aromatic epoxides proceeds either directly through loss of one molecule of aldehyde or ketone which leads to a symmetrical ion, or through rearrangement of the molecular ion into the isomeric carbonyl radical ion. Substituents on the aromatic ring have a marked influence on the fragmentation.
    Notes: Les époxydes aromatiques se fragmentent soit directement par élimination d'une molécule d'aldéhyde ou de cétone pour donner un ion symétrique soit aprés réarrangements de l'ion moléculaire en composés carbonylés. Les substituants du noyau ont une trés grande influence sur les fragmenta-tions.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210080123
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