Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 50 for “"hydrogen abstraction"”.
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Hydrogen Abstraction by the Nighttime Atmospheric Detergent NO3·: Fundamental Principles
… of much work. Despite this, studies on NO3· hydrogen atom transfer reactions have been somewhat neglected in favor of its more reactive oxidative pathways. The first section of the dissertation will highlight the role of substrate structure, solvent effects, and the presence of a polar …
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Tantalum and niobium alkylidene complexes via ligand induced alpha-hydrogen abstraction.
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1979.
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Investigation of Acrylated Alkyds
… alkyd model systems, evidence of grafting by hydrogen abstraction from glyceride unit was found. It was surmised that the acrylic macroradical combines with the glyceride radical to form the alkyd-acrylic copolymer. For the oleic alkyd model systems, the grafting site was primarily located at …
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Computational study on the selectivity of iron-containing hydroxylase
… and the distances between Fe=O oxo and the hydrogen atom to be abstracted. These findings would provide valuable guidance for predicting the reactivity of P450BM3 and other similar reactions where hydrogen abstraction is the rate-limiting step. The second part of the project is the study on …
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Photochemical Crosslinking Reactions in Polymers
… using group contribution techniques. A hydrogen abstraction induced radical crosslinking mechanism is explored in depth in Chapter 4. Benzophenone-derived additives are used to study photocrosslinking in thin films while varying multiple parameters: the irradiation time, additive to …
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Autocatalytic mechanism and functional consequences of covalent heme attachment in CYP4B1
… in the mammalian peroxidases, namely initial hydrogen abstraction from the carboxylate of Glu310 to form a carboxyl radical, hydrogen abstraction from the heme methyl, intramolecular electron transfer to generate a heme methyl carbocation, and finally, quenching of the carbocation with the …
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Steady State and Theoretical Investigations of Peptidylglycine α-Amidating Monooxygenase (PAM)
… perdeuterated cinnamic acid, one cannot rule out hydrogen abstraction from the Cα as this step may not be rate limiting for inactivation. This suggests that the activated oxygen species generated at CuM may be sufficiently reactive to abstract a hydrogen from an alkene to generate a vinyl radical. …
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Photochemistry of dibenzobarrelenes and [alpha]-adamantyl acetophenones in both the solution and crystalline state
… to the proposed ideal geometric requirements for hydrogen abstraction. Chiral crystals of carboxylic acid-amine salts were synthesized for solid state asymmetric induction studies. Some of these chiral salts were made from a prochiral, carboxylic acid group-containing a-adamantyl acetophenone …
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Computational thermochemistry of hydrocarbons, oxygenates, cyclic alkanes, and furans
… Kinetic rate parameters are calculated for hydrogen abstraction and chemical activation reactions. Recommended [Delta]H _{f 298} and carbon-hydrogen (C--H) BDEs for several normal and branched alkanes and ketones including corresponding radicals from loss of hydrogen atoms show strong …
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Theoretical studies of the dynamics of gas-phase and gas/surface atom+alkane reactions and of the structure and dynamics of water confined between hydrophobic surfaces
… Our results on the dynamics of atom+alkane hydrogen-abstraction reactions have shown good agreement with experimental metrics that are as diverse as product velocity distributions, excitation functions, angular distributions and rovibrational state distributions for diatomic products of the …
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The Reaction Kinetics of Neutral Free Radicals and Radical Ions Studied by Laser Flash Photolysis
… radical has been used as a chemical model for hydrogen abstractions in many enzymatic and biological systems. However, the question has arisen as to how well this reactive intermediate mimics these systems. In addressing this concern, absolute rate constants and Arrhenius parameters for …
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Internal pressure's role in the selectivity of the bromine radical
… SH2 ring opening of cyclopropylbenzene (kC) vs hydrogen abstraction from toluene (kH) by bromine atom was found to vary by nearly a factor of twenty as a function of solvent. The observed rate constant ratios correlate with the cohesive energy density of the solvent, which is approximately equal …
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Electron Transfer and Other Reactions Using Atomic Metal Anions
… to the neutral gas phase reactants. In addition, hydrogen abstraction and fluorine abstraction forming a neutral metal hydride or fluoride as well as the formation of multiply substituted metal-oxide/fluoride anions was also observed. Metal-complex anions observed from the gas phase reactions …
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In situ laser Raman studies of the mechanism of ethanol oxidation over supported molybdenum oxide
… by either of two rate-determining steps, α-hydrogen abstraction from the ethoxide intermediates to form acetaldehyde or β-hydrogen abstraction to form ethylene. The activation energy was found to be the same for the different supports at the similar loading levels. The link to reducibility …
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Ultrahigh Vacuum Studies of the Reaction Kinetics and Mechanisms of Nitrate Radical with Model Organic Surfaces
… direct addition to the vinyl group rather than hydrogen abstraction. Upon nitrate radical collisions with the surface, the initial reaction probability for consumption of carbon-carbon double bonds was determined to be (2.3 ± 0.5) -- 10-3. Studies of reactions of HO-SAM with the effusive source …
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Observation of the first titanium alkyl/alkyl complexes: The key intermediate in the Ziegler-Natta mechanism for the polymerization of alkenes
… of two coordinated ethylenes followed by $\beta$-hydrogen abstraction and reductive elimination. Interestingly, there is no insertion of ethylene into the Ti-CH$\sb3$ bonds. This behavior is probably a general feature of d$\sp2$ metal centers.
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Fundamental Studies of Reactions between NO3 Radicals and Organic Surfaces
… in situ with RAIRS. In the CH3-SAM studies, hydrogen abstraction was observed during NO3 exposure. The results presented in this thesis should help develop an understanding of the fundamental interfacial reaction dynamics of NO₃ radicals with organic surfaces.
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The use of chirped pulse millimeter-wave spectroscopy in chemical dynamics and kinetics
… which produces DNO products and bimolecular hydrogen abstraction reaction of NO with acetaldehyde resulting in HNO products. These reactions demonstrate the potential use of nitric oxide radical as a gas-phase catalyst to perform cracking of hydrocarbons and sugars.
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The partial oxidation of propene to acrolein over single-crystal Cu₂O
… is surface allyloxy (CH₂=CH-CH₂0-) which dehydrogenates to acrolein via hydride elimination on the carbon α to the oxygen. Thus, oxygen insertion precedes the final hydrogen abstraction in the partial oxidation pathway. Propene is also observed during allyl alcohol decomposition indicating …
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Transient frequency modulation absorption spectroscopy as a probe of gas-liquid scattering
… reactive hydrocarbon, most probably to hydrogen abstraction to form HCN. Subsequently, an entirely new TFMAS probe, with the capabilities to observe this unseen channel, was built to access the mid-infrared (MIR) region. Difference frequency generation (DFG) of tuneable NIR and …
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