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Showing 1 to 20 of 42 for “"kinetic isotope effect"”.
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Intermolecular Carbon-13 Kinetic Isotope Effect in the Thermal Structuralisomerization of Cyclopropane
Made available in DSpace on 2014-12-09T17:35:48Z (GMT). No. of bitstreams: 1 6711922.pdf: 6434035 bytes, checksum: 0833c7069c2960fd1a7276501a99f19b (MD5) Previous issue date: 1967
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Deuterium Enrichment and the Kinetic Isotope Effect during Ruthenium Catalyzed Fischer-Tropsch Synthesis
… is about 1.4, indicating a normal isotope effect. However, the ratio of [1-alkene]H/[1-alkene]D was around 0.9, indicating a different pathway for production than 2-olefins. We attempt to explain these experimental facts by the modified alkylidene mechanism. </p>
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Kinetic Isotope Effect of the Oxidative Addition Reaction of Hydrogen to Vaska's Compound
… temperature range 0-50(DEGREES)C in toluene. The kinetic isotope effect, i.e., the ratio of the rate constants k(,H(,2))/k(,D(,2)), was determined over this temperature range. The kinetic isotope effect varies substantially with temperature, being inverse (k(,H(,2))/k(,D(,2)) = 0.848 at …
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Carbon-13 Kinetic Isotope Effect Studies in the Oxidation of Formic Acid/formate Ion by Thallium (Iii) and Cobalt (Iii) Ions
Made available in DSpace on 2014-12-13T20:10:34Z (GMT). No. of bitstreams: 1 7913601.pdf: 4483498 bytes, checksum: 71e0b0b1fe95a3525439f6e683632e50 (MD5) Previous issue date: 1978
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Palladium-Catalyzed Alkenylsilanol Cross -Coupling Reactions: Method Development and Mechanistic Analysis
… examined through the natural abundance 13C NMR kinetic isotope effect (KIE) studies. This provided evidence for either palladium-olefin complexation or a Heck-type carbometalation as the turnover-limiting step for these cross-coupling reactions.
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Lewis Base Catalyzed Enantioselective Aldol Additions: Preparative and Mechanistic Studies
Kinetic studies using ReactIR and rapid injection NMR (RINMR) spectroscopy have confirmed the existence of dual mechanistic pathways involving either one or two phosphoramides. Determination of Arrhenius activation parameters revealed that aldol addition occurs through the reversible albeit …
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Mechanistic Studies of the Chemical Vapor Deposition of Ceramic and Metal Films From Organometallic Precursors
… to titanium carbide under CVD conditions. A kinetic isotope effect $(k\sb{\rm\alpha (H)}/k\sb{\rm\alpha (D)} = 5.2 \pm 0.4)$ upon deuterating the alkyl groups at the $\alpha$ positions provides clear evidence that the initial step in the thermolysis is an $\alpha$-hydrogen elimination …
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Synthesis of a Series of Secondary Peresters: An Investigation of Their Thermolyses and Chemiluminescence
… carboxylic acid. The study of the reaction kinetics and kinetic isotope effect indicate that the unimolecular thermolysis proceeds by homolysis of the oxygen-oxygen bond. Electronically excited states are formed in the thermolyses of these peroxyesters. These are detected by their …
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Control of regioselectivity:oxidation and deprotection
… side-on complex of either an agostic or 4-type. Kinetic studies show no evidence of an agostic interaction, and thus an 4-complex is more likely. Attempts at achieving catalytic activity in the formation of aldehydes are unsuccessful with small-molecule reoxidants. However, the use of …
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Mechanochemistry: Redefining the Paradigm of Organic Chemistry
… reaction mechanism studies such as kinetic isotope effect (KIE) and Hammett analysis, combinedly verified the importance of mechanochemistry for green organic synthesis.
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SHAPING ORGANIC SYNTHESIS WITH LIGHT-DRIVEN PROCESSES
… I focused on developing a method to analyze the kinetic isotope effect (KIE) through Raman spectroscopy in flow conditions.
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Development of Earth Abundant Metal-Catalyzed Reactions to Construct Heterocycles
… to efficiently construct N-arylpyrroles. Kinetic studies revealed a first-order rate dependence in catalyst, oxazine, and silane concentrations, and an inverse kinetic order in acetate was observed. Kinetic isotope effect measurements, and Eyring analysis provided mechanistic insight to …
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The development and application of metal-catalyzed processes for organic synthesis
… bearing a variety of functional groups can be effectively coupled to diethyl malonate in high yields using inexpensive and widely available reagents, making this a superior method to those previously described that employ copper reagents or catalysts. The functional group tolerance of the …
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Isotope ratios in source determination of formaldehyde emissions
… It is possible to distinguish the 13C/12C isotope ratio of UF resins from the isotope ratio of plant biomass. Conditions during and after composite hot-pressing promote reactions that generate formaldehyde from wood and UF resin, and the kinetic isotope effect continuously lowers the …
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The Chemistry of Methanol On Gold and Gold Based Bimetallic Clusters On TiO2 (110) Single Crystal
… intermediates occurred more efficiently. This effect transposed into a shift to lower production temperatures and increased activity for the proposed disproportionation of two methoxy intermediates to produce methanol and formaldehyde at 580K. It was also discovered through the substitution of …
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Synthesis of N-Heterocycles and Thiocines via Electrophilic Divalent Reactive Intermediates
… acid to promote the formation of benzimidazoles. Kinetic isotope effect mechanistic studies suggested that benzimidazole formation occurs through oxidation of the piperidine nitrogen followed by an intramolecular product-determining E2 elimination. The emergence of electrochemistry as a novel way …
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EXPLORATION AND MECHANISTIC STUDY OF WEAKLY COORDINATING ANIONS UNDER THERMAL AND PHOTOCHEMICAL CONDITIONS FOR SELECTIVE TRANSFORMATIONS OF C-C MULTIPLE BONDS
… focus of this work has been to acknowledge the effects of anions in transition metal-based systems. In this respect, a novel family of weakly coordinating anions (imadazolylphenyl or IMP anions) in addition to traditional anions were compared under both thermal and photochemical conditions. A …
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Towards new model systems for the study of proton-coupled electron transfer
… bulk solvent or to the phosphate buffer. A minor kinetic isotope effect for the rate of charge separation was found with kH/kD = 1.8 + 0.1 ps. Preliminary synthetic attempts of coupling the ET event to the PT event was accomplished by appending xanthene "Hangman" scaffolds to the 4' position of …
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Rational Design of Supported Metal Catalysts for Carbonyl Reduction During Biomass Upgrading
… outcomes include the detailed macro- and micro-kinetic analysis of hydrogenation of acetone. The apparent reaction orders of hydrogen and acetone, apparent activation energies, and observed kinetic isotope effects over a large range of temperatures and concentrations (compound partial pressures) …
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