- Steric factors in liquid-phase oxidation of olefins with iso structure
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Products of liquid-phase oxidation of 2-methyl-2-butene and 2-methyl-2-pentene were studied by NMR and IR spectroscopy. Steric hindrances in liquid-phase oxidation of olefins with iso structure were shown to arise from branching of the alkyl group at the
- Voronenkov,Simonov,Yablonskii,Koshel',Voronenkov
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p. 318 - 320
(2007/10/03)
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- Radical-Stabilization-Energy - the MMEVBH Force Field
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Making use of the VB method of Malrieu et al. a force field has been developed, which allows to calculate heats of formation of hydrocarbons (conjugated and non-conjugated olefins, radicals and diradicals) with high accuracy.With this method radical stabilization energies (RSE) for a great number of delocalized radicals are calculated and compared with experimental values, derived from shock-tube measurements of dissociation energies or from rotational barriers of substituted olefins.A detailed analysis of the RSE with respect to structure, substituents, strain, and aromaticity is presented. - Key Words: Resonance energy / Heats of formation / Single pulse shock tube / Intrisic rotational barrier
- Roth, Wolfgang R.,Staemmler, Volker,Neumann, Martin,Schmuck, Carsten
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p. 1061 - 1118
(2007/10/02)
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- Time-Resolved Observation of Sequential Bond Cleavage in a Gas-Phase Azoalkane
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The gas-phase photodissociation of an unsymmetrical azoalkane, 3-(methylazo)-3-methyl-1-butene, was studied with time-resolved coherent anti-Stokes Raman spectroscopy (CARS) to probe for product formation.Appearance kinetics were measured for all three primary photoproducts.The results indicate a two-step dissociation mechanism in which the 1,1-dimethylallyl fragment is formed within 2 ns of excitation, whereas the methyl radical and N2 are formed through decay of reaction intermediate having a lifetime of 12 +/- 2 ns.These findings mark the first direct demonstration of a stepwise homolysis mechanism for an azoalkane.
- Adams, J. Stephen,Burton, Katherine A.,Andrews, B. Kim,Weisman, R. Bruce,Engel, Paul S.
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p. 7935 - 7938
(2007/10/02)
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- The Reactions of t-Butoxyl with Unsaturated Hydrocarbons: Structure and Reactivity of Allylic Radicals
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A radical trapping technique employing 1,1,3,3-tetramethylisoindolin-2-yloxyl (1) as scavenger has been used to study the reactions of t-butoxy radicals with propene, 2-methylpropene, but-1-ene, (E)- and (Z)-but-2-ene, 3-methylbut-1-ene, buta-1,3-diene and 2-methylbuta-1,3-diene.Relative rates of double bond addition and of allylic hydrogen abstraction have been measured and are discussed, as are the relative stabilities of the products formed.The allylic radicals generated in these systems react with (1) mainly by coupling at the more substituted terminus of the radical ? system.Substituent effects on this regioselectivity may be explained in terms of the electrophilicity of (1).
- Cuthbertson, Matthew J.,Rizzardo, Ezio,Solomon, David H.
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p. 1957 - 1973
(2007/10/02)
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