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  • 11
    Electronic Resource
    Electronic Resource
    The cycloaddition of the 1,3-butadiene radical cation with acrolein and methyl vinyl ketone (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 24 (1989), S. 637-646 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1,3-butadiene radical cation reacts with acrolein and methyl vinyl ketone to produce ‘stable’ adducts. The nature of the reaction and the structures of the adducts were investigated by collisional activation decomposition (CAD) combined with tandem mass spectrometry (MS/MS), and also by Fourier transform mass spectrometry. The CAD spectra of gas-phase adducts were compared with those of suitable model compounds. On that basis, it was determined that the 1,3-butadiene radical cation undergoes a cycloaddition with these α,β-unsaturated carbonyl compounds. The butadiene radical cation serves as the ‘ene’, and the acrolein and methyl vinyl ketone react as dienes, forming cycloadducts having 2-ethenyl-2,3-dihydropyran radical cation structures.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210240821
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  • 12
    Electronic Resource
    Electronic Resource
    Reactions of propene and cyclopropane radical cations with neutral ethylene (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 185-192 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas-phase reactions of propene and cyclopropane radical cations with neutral ethylene were investigated by using Fourier transform, chemical ionization and tandem mass spectrometries. Both reactions form covalent C5H10 adduct ions. The adduct ions are hypothesized to form initially as distonic radical cations that isomerize via a substituted cyclopropane intermediate and are detected as the most stable C5H10 isomer, the 2-methylbut-2-ene radical cation. The rate constant for each reaction is approximately 20% of the theoretical collision rate, indicating that product ions are formed in one out of every five collisions of the C3H6 radical cations with neutral C2H4.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210280309
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  • 13
    Electronic Resource
    Electronic Resource
    Elimination of acetic acid from protonated 4,5-diacetoxyphenanthrene and 2,2′-diacetoxybiphenyl: An example of an ion chemistry proximity effect (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 1184-1188 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Protonated 4,5-diacetoxyphenanthrene and 2,2′-diacetoxybiphenyl dissociate, owing to the interaction of the two acetoxy groups, by eliminating a molecule of acetic acid. This novel proximity effect, which occurs for a fast atom bombardment-produced closed-shell ion, was examined in detail using tandem mass spectrometric methods. This process, which was first observed in the decompositions of acetylated complex natural products such as stentorin and hypericin, may serve as a general process for determining the proximity of hydroxyl groups in polycyclic aromatic compounds.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210281033
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  • 14
    Electronic Resource
    Electronic Resource
    Synthese von Hydroxyguanidinen aus Chlorformamidinen und OximenTeil der Dissertation M. Gross, Martin-Luther-Universität, Halle 1971. (1974)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 316 (1974), S. 434-442 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N2-Aryl-N1,N1-dialkylchlorformamidine 1 reagieren mit Oximen über hydrolyseempfindliche Zwischenprodukte zu 2-Hydroxy-1-aryl-3,3-dialkylguanidinen 3.Diese Hydroxyguanidine bilden mit Benzoylchlorid O- und O,N-acylierte Verbindungen, mit Chlorameisensäureestern entstehen 3-Dialkylamino-4-aryl-5-oxo-Δ2-1,2,4-oxadiazoline 7. Die Reaktion mit Alkylhalogeniden führt zu 2-Alkoxy-1-aryl-3,3-dialkylguanidinen 8, und die katalytische Hydrierung liefert 1-Aryl-3,3-dialkylguanidine. Bei der Abspaltung der Oximinogruppe im saure Medium in Gegenwart von Oxydationsmitteln entstehen entsprechend substituierte Harnstoffe.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19743160311
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  • 15
    Electronic Resource
    Electronic Resource
    Emulsifier-free polymerization in aqueous media (1955)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 16 (1955), S. 549-576 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polymerization in solution of a variety of water-soluble monomers with a variety of water-soluble redox initiators is described and a detailed study is reported on the polymerization, in aqueous solution, of methyl vinyl ketone and of methyl methacrylate under the influence of potassium sulfate-silver nitrate. Keeping the persulfate concentration constant and varying the silver nitrate or, conversely, keeping the silver nitrate constant and varying the persulfate, it is found that, except at very high concentration of catalyst, both the rate of polymerization and the molecular weight of the polymer bear a linear relation to the square root of the catalyst concentration, in harmony with the general theory of catalyzed bulk and emulsion polymerization. The molecular weight of the polymer formed diminishes with increase in the temperature of polymerization. The study of redox polymerization in water, without emulsifier, has been extended to the case of a mixture of a water-soluble and a water-insoluble monomer, and it has been found that copolymerization proceeds at a reasonable rate and frequently forms a stable latex. The copolymerization of styrene and 5 or 10 per cent of its weight of methacrylonitrile in water under the influence of a water-soluble persulfate-bisulfite redox pair has been examined with some closeness. Polymerization is apparently initiated in the aqueous solution, since, contrary to the state of affairs in emulsion polymerization, water-soluble retarders are more effective than oil-soluble ones, when the retarder is added at the outset. If the retarder is added at a later stage of polymerization, oil-soluble reagents are more effective than water-soluble ones. The water-soluble monomer enters into the polymer at a greater rate than the water-insoluble one, but it appears that, even at the earliest stage at which it is practicable to take samples co-polymerization occurs. The influence of catalyst concentration on the rate of polymerization, the molecular weight of the polymer, and the latex particle size was examined.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1955.120168239
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  • 16
    Electronic Resource
    Electronic Resource
    Amalgam electrodes: Direct electrochemical generation of cadmium macrocyclic complexes (1992)
    Weinheim : Wiley-Blackwell
    Electroanalysis 4 (1992), S. 19-26 
    Details
    ISSN: 1040-0397
    Keywords: Amalgam electrode ; cadmium ; macrocyclic complexes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrochemical oxidation of cadmium amalgam was studied in the nonaqueous solvents CH2Cl2, 1,2-C2H4Cl2 and propylene carbonate. Significant coordination effects were observed between the electrogenerated Cd(II) ions and 18-membered macromonocyclic ligands, each containing six Lewis bases heteroatoms: 18-O6, 18-S6, 18-N2O4, and 18-N6. The stoichiometries and the stabilities of the resulting complexes were determined. These stabilities increase from 18-O6 or 18-S6 to 18-N6.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140040106
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  • 17
    Electronic Resource
    Electronic Resource
    Determination of the appearance potentials of [C3H7]+ ions by a computerized electron distribution difference procedure (1974)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1974), S. 1217-1222 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple computerized electron distribution difference method has been developed using a conventional mass spectrometer and an on-line computer. Using the system, ionization potentials for various propyl halides were measured and found to agree well with photoionization data. The appearance potentials for [C3H7]+ agreed well with literature values, except for 1-propyl bromide and 1- propyliodide which gave values approximately 0.7 eV lower than previous reports. The results are interpreted to indicate threshold formation of the sec-propyl ion from all propul halides.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210091211
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  • 18
    Electronic Resource
    Electronic Resource
    The internal energy of product ions formed in mass spectral reactionsMetastable Ion Characteristics, XXIII. Part XXII, F. W. McLafferty, P. F. Bente, III, R. Kornfeld, S.-C. Tsai and I. Howe, J. Amer. Chem. Soc. 95, 2120 (1973). (1974)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1974), S. 525-535 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Major factors which determine the distribution of internal energy of a primary product ion A+, P(E)A+, at formation are delineated in terms of the quasi-equilibrium theory and a variety of experimental evidence is offered to support these conclusions. These major factors include: the P(E) of the molecular ion, the rate constants as a function of energy, κ(E), for M+·→A+ + N0 and for competing reactions of M+·, and the partitioning of excess internal energy between A+ and N0. The ‘fluctuation effect’ on this partitioning makes P(E)A+ relatively insensitive to many structural and energy changes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210090510
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  • 19
    Electronic Resource
    Electronic Resource
    The Chemistry of C6H6O radical cations: A study of rearrangement reactions of halogen substituted ethyl phenyl ethers (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 474-481 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New experimental data on the rearrangement reaction of various phenoxyethyl halides to give [C6H6O]+· are presented and compared with previous studies so that a coherent picture of this process can be developed. By examining the metastable kinetic energy release for low energy decomposing molecular ions of the phenoxyethyl halides, it has been concluded that formation of [C6H6O] occurs by competitive 1,2 and 1,3 hydrogen shifts from the alkyl carbons to oxygen followed by a rate determining C—O bond cleavage. This is substantiated by the absence of a primary hydrogen isotope effect. For more highly activated molecular ions, a new mechanism comes into play as evidenced by the appearance of a small hydrogen isotope effect. It is postulated that this third mechanism involves transfer of the alkyl hydrogen to the ortho position of the ring by a rate determining 1,5 shift, followed by a 1,3 hydrogen shift from the ortho methylene group to oxygen and rapid C—O bond cleavage. This 1,3 hydrogen shift to oxygen appears to be ‘catalysed’ by the halogen atoms yielding phenol ions. No indications have been found for the formation of tautomeric 2,4-cyclohexadienone ions. Furthermore, highly activated molecular ions produce [C6H6O]+· which can undergo metastable decomposition to lose carbon monoxide. Kinetic energy release measurements for the latter reaction show that the majority of these [C6H6O]+·ions have been formed as phenol ions as well. These arguments are supported by energetic measurements and by comparisons with previous ion cyclotron resonance and collisional activation studies.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210140904
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  • 20
    Electronic Resource
    Electronic Resource
    Elemental compositions from daughter ion spectra of m1+ and [m1 + 1]+: Some applications of the method (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 23 (1988), S. 712-718 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The elemental compositions of ions can be determined in tandem mass spectrometry by comparing the daughter ion spectra of the m1+ and [m1 + 1]+ ions. The method is demonstrated for mass-analyzed ion kinetic energy spectra but is applicable to all types of daughter ion spectra, including complex collisionally activated dissociation spectra. In this work, the method is applied to compounds that produce daughter ions of known elemental compositions, and the errors and limitations are evaluated. Following that test, the procedure is applied to a compound that may produce daughters of more than one possible elemental composition. The method is sometimes useful even if the formula of the parent is not known; that is, the formulae of unknown parent and daughter ions may be found. Locating a specific atom in an isotopically labeled molecule is another capability of the method. The basic equation of the method was generalized and incorporated into a computer program for performing the calculations.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210231007
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