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  • 1
    Electronic Resource
    Electronic Resource
    The structure of radicals produced by the radiolysis of glassy cyclohexanol (1985)
    Springer
    Journal of radioanalytical and nuclear chemistry 93 (1985), S. 153-161 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The stabilization of electrons and radicals resulted from hydrogen atom loss in the 2-, 3- and 4-positions of the cyclohexane ring and 1-hydroxycyclohexyl radicals in γ-irradiated glassy cyclohexanol was shown with the ESR technique. The stabilization of electrons and alkyl-type radicals was observed for the first time. The total yield of radicals and electrons is equal to 3.7±0.5 units per 100 eV of absorbed energy. Upon heating the irradiated cyclohexanol, the alkyl-type radicals interact with the alcohol producing 1-hydroxycyclohexyl radicals /within the −155 °C÷115 °C temperature range/. Using the spin trap C-phenyl-N-tert-butylnitrone, it has been shown that this reaction is not acompanied by the diffusion of radicals into the matrix but occurs due to the cage abstraction of hydrogen atom from an alcohol molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02164362
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  • 2
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Spin-Trapping-Kinetik in Systemen von Radikalen unterschiedlicher Reaktivität. Die Photolyse von α-Phenylbenzoin in Gegenwart von Benzyliden-tert.-butylamin-N-oxid (1985)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 749-758 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations on Spin-Trapping Kineties in Radical Systems with Different Reactivity. Photolyses of α-Phenylbenzoine in the Presence of Benzylideneter. -butylamine N-oxideAs a model system to study the spin-trapping kinetics of systems forming two radicals of different reactivity α-phenylbenzoine (PhB) was chosen. The photolysis of PhB forms benzoyl (B·) and diphenylketylradikals (K·), respectively, which can be trapped by benzylidene-tert-butyl-amine N-oxide (PBN), as a spin trap. The rate constants of radical addition to PBN and their reactions with the spin adducts were determined by means of flash photolysis and kinetic calculations of the PBN concentration dependence. For B· and K· addtion rate constants to PBN of k1 = 8,1 × 105 M-1s-1, and k2 = 5,8 · 104 M-1s-1, respectively, were found. The rate constants for the reactions of B· and K· with the spin adducts are in the order of 109…1010 M-1s-1.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19853270507
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  • 3
    Electronic Resource
    Electronic Resource
    X- and gamma-radiolysis of phosphate esters. Electron spin resonance study by the spin trap technique (1988)
    Springer
    Journal of radioanalytical and nuclear chemistry 127 (1988), S. 177-192 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Radicals formed at X- and γ-radiolysis of glass and liquid tri-n-butylphosphate /TBP/, di-n-butylphosphate /DBP/, di/2-ethylhexyl/phosphoric acid /DEHPA/, tri-p-tolylphosphate /TTP/ and di-n-butyl-n-butyl phopsphonate /DBBPN/ were studied using the technique of spin trap using C-phenyl-N-tert. butylnitrone /PBN/ and 2-methyl-2-nitrosopropane /MNP/ as spin trap agents. When using PBN, nitroxyl radicals generated by the spin trap of hydrogen atoms and labile radicals of phosphates or phosphonate were identified after irradiation in vacuum. Radiation-chemical yield of spin adducts was observed, as well as their thermal stability at 293 K, rate constants and half-time of decay and free activation energy of the decay of spin adducts. Mechanism of generation and decay of nitroxyl radicals is discussed. The spin adducts with MNP have a relatively low stability and superposition of some adducts spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02164863
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  • 4
    Electronic Resource
    Electronic Resource
    ESR spectra of radicals at a low-temperature X-radiolysis of phosphates (1988)
    Springer
    Journal of radioanalytical and nuclear chemistry 127 (1988), S. 37-49 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract ESR spectroscopy at 77 K has been used for the investigation of radicals formed in the low-temperature X-radiolysis of tri-n-butylphosphate /TBP/, di-n-butylphosphate /DBP/, di /2-ethylhexyl/phosphoric acid /DEHPA/, tri-p-tolylphosphate /TTP/, di-n-butyl-n-butylphosphonate /DBBPN/. Besides the phosphate radicals also hydrogen atom stabilization in the matrix has been observed. In the presence of oxygen peroxy radicals occur as well. The structure of the radicals and reaction mechanisms are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02165504
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  • 5
    Electronic Resource
    Electronic Resource
    Regiospecific oxidation of alkanesulfonamides to 3-oxoalkanesulfonamides (1988)
    Springer
    Russian chemical bulletin 37 (1988), S. 1401-1405 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. N-nonsubstituted alkanesulfonamides under the action of Na2S2O8-AgNO3-CuSO4 are transformed into 3-oxoalkanesulfonamides by regiospecific γ-oxidation with yields of 90–100% based on consumed substrate. 2. The reaction mechanism includes generation of nitrogen-centered sulfonylamidyl radicals and rearrangement with 1,5-hydrogen migration to carbon centered radicals as recorded by EPR. The regiospecificity of the 1,5-hydrogen migration is determined probably by complex formation of the sulfonylamidyl radicals with silver ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00962750
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  • 6
    Electronic Resource
    Electronic Resource
    Photoinitiierte Polymerisation mit Dialkoxythiocarbonyldisulfiden - eine Polymerisationsreaktion mit PrimärradikalabbruchLichtinitiierte Polymer- und Polymerisationsreaktionen 37. Mitt.; 36. Mitt.: U. Müller, H.-J. Timpe, K.-G. Häussler, K. Peters, R. Wagner: Acta Polym. 41 (1990) 54. (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 1013-1028 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoinitiated Polymerization with Dialkoxy Thiocarbonyl Disulfides - a Polymerization Reaction with Primary Radical TerminationThe photoinduced free radical polymerization of methyl methacrylate (MMA) and some other vinyl monomers using dialkoxy thiocarbonyl disulfides (1-4) as photoinitiators was studied. The photolysis of these initiators leads to cleavage of the S—S bond, which was determined by spin trapping experiments with phenyl tert-butyl nitrone. No evidence was found for a further thermal decomposition of the primary alkoxy thiocarbonyl sulfide radicals (R·) at room temperature. In the absence of scavengers the primary radicals react back exclusively to the initial compounds, due to a strong cage effect. By means of UV spectroscopic measurements and in the presence of MMA the quantum yields of the initiator decomposition were detected to be 0.8. The polymerization of acrylic and methacrylic derivatives can be initiated by the R·, contrary to the situation with fumarates and maleates. The mechanism of MMA polymerization depends on the light intensity absorbed by the initiators. At high intensities the combination of primary and polymer radicals terminates the chain reaction. This follows from the measured monomer exponent of α = 2, the light intensity exponent of β = 0,2 and the number of thiocarbonyl end groups of 2 in the polymers isolated. Contrary to this, in the low intensity region the experimental data obey the ideal kinetic equation. Kinetic modelling gives evidence for an interaction of the monomer with the cage radicals.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320619
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