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  • 1990-1994  (7)
  • 1975-1979  (1)
  • 1915-1919
  • Chemistry  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 19 (1990), S. 613-618 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several aminophenanthrenes have been examined with electron impact mass spectrometry. The trifluoroacetic anhydride (TFAA) and perfluoropropionic anhydride (PFPA) derivatives of 4-aminophenanthrene have been studied with electron impact as well as both positive and negative ion chemical ionization mass spectrometry utilizing methane as a reagent gas. The resulting mass spectra indicate a loss of water from the derivatives and a mechanism is proposed to account for this loss. The spectra also indicate unique fragmentation patterns associated with the position of the substituent, particularly the four position which is in the region of the molecule termed the bay region. Another interesting aspect is the spectral differences observed for the TFAA and PFPA derivatives of 4-aminophenanthrene. The positive ion chemical ionization mass spectrum of the TFAA derivative indicates an ion [M + H — H2O]+; however, the mass spectrum of the PFPA derivative of 4-aminophenanthrene indicates no water loss from the [M + H]+ ion. The negative ion chemical ionization mass spectra of the two derivatives are also very different. The mass spectrum of the TFAA derivative shows an [M — 18]- ion and the PFPA derivative shows successive losses of HF with no apparent loss of water.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 19 (1990), S. 520-522 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Since the methylation of acids with diazomethane is widely used in trace analysis, it is extremely important for those using this technique to be alert to the analysis of compounds containing other functional groups which might become methylated with high concentrations of diazomethane. We have shown that by adding an excess of diazomethane to dansylated amino acids, not only is the methyl ester formed, but the products can be further methylated. The only remaining acidic hydrogen in the molecule is the hydrogen attached to the sulfonamide nitrogen, and the mass spectrometry results indicate that the methyl ester is formed first, and the N-methylated derivative is formed with excess diazomethane.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 1 (1990), S. 109-115 
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (R,R)-Butanediol (dichloromethyl)boronate (1) with 1 equiv. allylmagnesium halide yields (R,R)-2,3-butanediol (1S)-(1-chloro-3-butenyl)boronate (3) together with the diallylated product (R,R)-2,3-butanediol (1-allyl-3-butenyl)boronate (4). The formation of 4 is unprecedented in reactions of α-chloroboronic esters with Grignard reagents. With methylmagnesium bromide 3 yielded (R,R)-2,3-butanediol (1S)-(1-methyl-3-butenyl)boronate (5), which failed to hydrolyze with water. Hydrolysis of 3 yielded impure α-chloroboronic acid, which was esterified with pinacol and treated with methylmagnesium bromide to form 6, which with (dichloromethyl)lithium followed by methylmagnesium bromide yielded diastereomeric boronic esters 7 and 8. Oxidation by hydrogen peroxide yielded (2S,3S)- and (2R,3S)-3-methyl-5-hexen-2-ol (9 and 10, ees unknown). Treatment of (s)-pinanediol allylboronate (11) with (dichloromethyl)lithium at -100°C followed by zinc chloride at up to 25°C has proceeded in the normal way to form (s)-pinanediol (1S)-(1-chloro-3-butenyl)-boronate (12), which has been elaborated via 13, 14, and 15 to (2S,3S)-3-methyl-5-hexen-2-ol (9) in 95% de.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 22 (1976), S. 1050-1055 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1056-1062 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Reactive extrusion of functionalized polymers provides a convenient, commercially attractive route for the preparation of copolymers useful in compatibilization of polymer blends. In the current study, the grafting chemistry of maleic anhydride to poly(phenylene oxide) in the absence of a radical initiator is contrasted to that of efficient quinone-methide trapping agents such as maleimides. In the case of maleic anhydride, functionalization is shown to occur randomly along the polymer backbone whereas maleimides react to give both main chain and end-group derivatives. Use of this anhydride-functionalized polyfphenylene oxide and an end-group functionalized analog in blends with polyamide-6,6 affords high levels of graft and diblock copolymers respectively, sufficient for the preparation of highly ductile materials. The properties of these polyamide blends are found to depend on the amount of copolymer formed during extrusion with final copolymer levels being in turn returned to the degree of anhydride functionalization. The properties and morphology of blends containing graft or diblock copolymers derived from main-chain and end-group functionality respectively, are rationalized in terms of the relative effectiveness of different copolymer structures in blend compatibilization.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 20 (1991), S. 191-197 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Accurate tail-to-peak intensity ratios are extracted from the spectra produced in a Si(Li) detector by x-rays of energies 2-10 keV. The widely used model of a surface layer of incomplete charge collection fails to explain the energy dependence of these data. The model is augmented to include loss of photoelectrons travelling back into the ICC layer from an interaction in the active silicon region; this gives excellent agreement with experiment. It is shown that the detection efficiency in the region of low x-ray energy may be deduced from the tail-to-peak ratios, together with measurement of the thicknesses of the beryllium window and the metal contact; a potential source of error in measuring the latter by the popular fluorescence technique is demonstrated.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 21 (1992), S. 223-227 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: If the lineshape response of a Si(Li) detector is measured using monoenergetic x-rays provided by a monochromator, it must be convoluted by a Lorentzian of appropriate width in order to represent the lineshape encountered in directly measured x-ray spectra. It is shown that the Lorentzian component is responsible for a significant fraction of low-energy peak tailing, a phenomenon usually attributed to detector imperfections.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Journal of Vinyl and Additive Technology 14 (1992), S. 123-124 
    ISSN: 0193-7197
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Blends of intrinsically conductive polymers (ICPs) with conventional thermo-plastics exhibit conductivities approaching those of neat ICPs and can be processed using conventional thermoplastic processing equipment. They display good environmental stability and mechanical properties suitable for commercial applications.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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