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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Contributions to the study of heats of adsorption of gases and heats of gaseous reactions on catalyst surfaces ...

Flosdorf, Earl William, January 1930 (has links)
Thesis (Ph. D.)--Princeton University, 1929.
42

Theoretical and synthetic aspects of substituted trimethylenemethane palladium intermediates

Nanninga, Thomas N. January 1985 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1985. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 178-189).
43

Synthesis of pyridine-bis(imine) iron compounds for future polymerization studies

Weber, Ronald J. January 2006 (has links)
Thesis (M.S.)--Villanova University, 2006. / Chemistry Dept. Includes bibliographical references.
44

Biomimetic synthesis of catalytic materials

Varpness, Zachary Bradley. January 2007 (has links) (PDF)
Thesis (Ph.D.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Trevor Douglas. Includes bibliographical references (leaves 208-224).
45

An investigation of the effect of chain length on stereo-regulation with C₂ symmetric metallocene catalysts /

Amer, Ismael January 2006 (has links)
Thesis (MSc)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.
46

Microfibrous entrapped catalysts and sorbents microstructured heterogeneous contacting systems with enhanced efficiency /

Kalluri, Ranjeeth Reddy. January 1900 (has links)
Thesis (Ph.D.)--Auburn University, 2008. / Adviser: Bruce J. Tatarchuk. Includes bibliographical references.
47

The preparation of binuclear and polynuclear methyl complexes of palladium as catalyst precursors in phenylacetylene polymerization

Sibanyoni, Johannes Mlandu January 2007 (has links)
Magister Scientiae - MSc / This study focused on the development of binuclear and multinuclear catalyst for use in vinylic monomer oligomerization and polymerization. The main objective was to develop new homogeneous catalysts systems with hopefully improved activity, selectivity and stability. / South Africa
48

Kinetic studies on catalytic properties of rhodium complexes in solution

Rempel, Garry Llewellyn January 1968 (has links)
Kinetic studies of a number of interesting and significant reactions involving activation of molecular hydrogen, simple olefins and carbon monoxide by solutions of rhodium trichloride trihydrate are described. RhCl₃∙3H₂O in N,N-dimethylacetamide solution is an effective catalyst for the homogeneous hydrogenation of a variety of substituted ethylenes as well as for ethylene itself. The kinetics of the RhCl₃∙3H₂O catalyzed hydrogenation of maleic acid in dimethylacetamide media suggest a mechanism involving an initial hydrogen reduction of rhodium (III) to rhodium (I), which is stabilized in solution by rapid complexing with maleic acid. The rhodium (i) maleic acid complex undergoes a subsequent reaction with hydrogen to produce succinic acid and rhodium (l) again, via an intermediate containing both coordinated maleic acid and hydrogen. In aqueous acid-chloride solution, rhodium (I) olefin complexes also form, but no subsequent homogeneous hydrogenation is apparent. Solutions of RhCl₃∙3H₂O in dimethylacetamide react with ethylene to form a rhodium (I) ethylene complex. Examination of the kinetics of the reaction suggest that the reaction proceeds through an initial dissociation of a chloro rhodium (III) species. A resulting intermediate rhodium (III) ethylene complex is decomposed by water to rhodium (I) which is stabilized by rapid reaction with further ethylene as an olefin complex. The resulting rhodium (I) ethylene complex subsequently acts as a dimerization catalyst for the production of butenes. Ethylene catalyzes at ambient temperatures the production of the [Rh(H₂O)₄Cl₂ ]⁺ cation from aqueous solutions of RhCl₃∙3H₂O; at higher temperatures metallic rhodium is formed. Carbon monoxide reacts with chlororhodate (III) complexes in aqueous HCl solution to form the anionic species [Rh(I)(CO)₂Cl₂]⁻. The observed kinetics indicate that [Rh(I)(CO)₂Cl₂]⁻ is autocatalytically produced; the mechanism postulated involves initial production of some [Rh(I)(CO)₂Cl₂]⁻ through a CO "insertion" reaction with a chlororhodate (III) complex. The [Rh(I)(CO)₂Cl₂]⁻ species Is then involved in a two electron transfer process via a chloride bridged [Rh(I)...Cl…Rh(III) ] intermediate to produce further Rh(I) more efficiently than by the initial direct insertion-reduction process. Carbon monoxide is catalytically activated through coordination to rhodium for subsequent reduction of rhodium (III) resulting from the electron transfer process. An inorganic substrate, ferric chloride, is catalytically reduced by [Rh(I)(CO)₂Cl₂]⁻ in this way. Kinetic studies of direct carbonylation of RhCl₃∙3H₂O in dimethylacetamide solutions have shown the importance of the presence of a water molecule for the production of the [Rh(I)(CO)₂Cl₂]⁻ species from an initially formed Rh(III)(CO) complex. The introduction of carbonyl groups into chlororhodate complexes is found to inhibit catalytic activity for the hydrogenation of olefinic substrates. / Science, Faculty of / Chemistry, Department of / Graduate
49

Syntheses, kinetic and homogeneous hydrogenation studies of ditertiary phosphine rhodium(I) complexes

Fung, Dawning Chui Mun January 1988 (has links)
The original purpose of this work was to investigate the catalytic properties of a series of Rh₂(CO)₄(P-P)₂ complexes (where P-P = ditertiary phosphines of the type PR₂(CH₂)nPR₂, R = alkyl or aryl) for hydroformylation. The preparation of Rh₂(CO)₄(P-P)₂ involves the synthesis of Rh(P-P)₂Cl, followed by reaction with NaBH₄ to give RhH(P-P)₂, which when treated with CO in benzene yields Rh₂(CO)₄(P-P)₂, as reported in the literature. The dimer, Rh₂(CO)₄(dpp)₂, where dpp = PPh₂(CH₂)₃PPh₂, was prepared and examined for its interaction with H₂, and H₂/CO, in order to test its capabilities for catalytic homogeneous hydroformylation. The interaction of Rh₂(CO)₄(dpp)₂ (49) with H₂, and the reaction of CO with RhH(dpp)₂ (52) to yield 49, are summarized as follows: [Formula Omitted] All the species shown, except 59, have been detected by ¹H and ³¹P{¹H} NMR spectroscopy. Formation of the monomeric hydride, 50, from 49, occurs at high [dpp]. The reaction of Rh₂(CO)₄(dpp)₂ and 6 equivalents dpp with synthesis gas (H₂ : CO = 1 : 1) gives initially 50 and R₂(CO)₄(dpp)₂ reforms after 30 minutes of interaction. This is consistent with the previous finding of low turnover rate for hydroformylation of 1-hexene using as catalyst the co-ordinatively saturated Rh₂(CO)₄(dpp)₂. Treatment of 52 in toluene with ~1 atm CO, followed by treatment with ~1 atm H₂, sets up the following equilibria (where dpp* = monodentate dpp): [Formula Omitted] The homogeneous hydrogenation of 1-hexene at 31° C, - 1 atm H₂, catalyzed by "the RhH(dpp)₂/CO/H₂ system" in toluene is ascribed to the formation of an unidentified "RhH" from 50 and/or 51. The H₂-uptake curve displayed an initial ("inductive") period required for the generation of an active species "RhH", a second period of maximum rate, and a final slowing down period. The mechanism suggested for homogeneous hydrogenation of 1-hexene catalyzed by the "RhH(dpp)₂/CO/H₂ system" is presented as follows: [Formula Omitted] The corresponding rate law for the maximum rate, consistent with the kinetic data, is given by: [Formula Omitted] where ["Rh"]t is total concentration of the active "RhH" catalyst. At high [1-hexene], where k₃[1-hexene] >> k₋₃ + k₄[H₂], the rate law is simplified to: Rate = k₄[H₂],["RhH"]t where ["RhH"]t ~ total rhodium concentration in solution. The values of k₃ and k₄ at 31° C were found to be 0.42 M⁻¹ s⁻¹ and 20 M⁻¹ s⁻¹ respectively. The Rh(dcpe)₂ ⁺X⁻ complexes (X = CI, BF₄, PF₆; dcpe PCy₂(CH₂)₂PCy₂) were prepared and found to have no reactions with NaBH₄ or LiAlH₄. Consequently, the dcpe carbonyl dimer could not be prepared. The Rh(p = p)₂ ⁺Cl⁻ complex, where p = p = PPh₂C₂H₂PPh₂, was isolated and characterized; its reaction with NaBH₄ was incomplete, partially generating RhH(p=p)₂. Treatment of the mixture with CO gave partially Rh(CO)(p=p)₂ ⁺Cl⁻ and another uncharacterized carbonyl complex. A single crystal X-ray structure determination of Rh(dcpe)₂ ⁺Cl⁻ showed that the geometry around Rh is distorted square planar. Also, the extremely air-sensitive species [RhCl(dcpe)• solv]n (solv = THF or 0.1 C₆H₆) and RhCl(dcpe)(CH₂Cl₂)•C₆H₆ were isolated. The interaction of Rh(dcpe)₂ ⁺Cl⁻ with small gas molecules was studied in order to test its potential as a catalyst. There is interaction between Rh(dcpe)₂ ⁺Cl⁻ and HCI, Cl₂, and CO, in CH₂C1₂. The reaction with HCI to give cis-RhHCl(dcpe)₂ ⁺Cl⁻ is extremely rapid. The use of stopped-flow kinetics and UV-VIS spectrophotometric techniques at 25° C gave an equilibrium constant of 4.2 x 10⁷ M⁻¹ for the reaction. The forward reaction was first-order in both [Rh(dcpe)₂ ⁺Cl⁻] and [HCI], indicating a concerted oxidative addition reaction. The RhHCl(dcpe)₂⁺ species reacts further with HCI to give RhHCl₂(dcpe) and the diphosphonium salt, dcpe(HCl)₂. The Rh(dcpe)₂ ⁺Cl⁻ complex reacts with Cl₂ to give RhCl₂(dcpe)₂ ⁺Cl⁻, which was also obtained by prolonged treatment of RhHCl(dcpe)₂ ⁺Cl⁻ with CDCl₃ The reaction of Rh(dcpe)₂ ⁺Cl⁻ with CO to give Rh(CO)(dcpe)₂ ⁺Cl⁻ yielded k on and k off values of 2.2 x 10⁻² M⁻¹ s⁻¹ and 5.02 x 10⁻⁴ s⁻¹ respectively at 25° C. The Rh(dcpe)₂ ⁺Cl⁻, complex was inactive as a catalyst for decarbonylation of benzaldehyde, or hydrogenation of 1-hexene. / Science, Faculty of / Chemistry, Department of / Graduate
50

CoMFA Study of Chiral Catalysts

Pradhan, Meeta 01 September 2005 (has links)
Submitted to the faculty of the University Graduate School in partial fulfillment of the requirements for the degree of Master of Science in the School of Informatics Indiana Univeristy / A QSAR using Comparative Molecular Field Analysis (CoMFA) is developed for a set of 23 catalysts containing bis-oxazoline or phosphino-oxazoline ligands that are known to induce asymmetry during the Diels-Alder reaction of N-2-alkenoyl-1, 3-oxazolidine-2-one with cyclopentadiene. It is shown that extemely high q2 statistics can be derived using standard modeling protocols when internal validation alone is done as well as when an external test set is used. From these models it is shown that approximately 70% of the variance in the observed enantiomeric excess can be attributed to the steric field and the remainder of the variance to the electrostatic field. Suggestions about how to improve the performance of inefficient catalysts are given the thesis.

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