Thesis (Ph. D.)--University of Delaware, 2006. / Principal faculty advisor: Klaus H. Theopold, Dept. of Chemistry and Biochemistry. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (November 14, 2006) Vita. Includes bibliographical references.

Thesis (Ph. D.)--Georgia State University, 2005. / Title from title screen. Al Baumstark, committee chair; Paul Franklin, David Boykin, Markus Germann, committee members. Electronic text (136 p. : charts (some col.)) : digital, PDF file. Description based on contents viewed June 7, 2007. Includes bibliographical references (p. 130-136).

No description available.

The reactions of acrylic and vinylacetic acids with Ph2PCl and Et3N give Ph2PO2CCH=CH2 (AAA) and Ph2PO2CCH2CH=CH2 (VAA) respectively. Both are found to undergo a facile rearrangment to give Ph2PP(O)Ph2 and AAA is also found to react with PPh3 to give Ph3P+-CH2CH2CO2-. Their reaction (1 mole ligand to 1 mole Rh) with [(RhCl(1,5 COD))2], gives complexes of the form [(RhCl(L)2], where L is AAA or VAA, in which the mixed anhydride ligands are bound via the phosphorus atom and the double bond. With AAA in a 1:2 mole reaction with [(RhCl(1,5 COD))2] or a 1:1 mole reaction with [(RhCl(C2H4)2)2l, the major products are [(RhCl(AAA))2 (Ph2POPPh2)] and [RhCl(AAA)2], in which the mixed anhydride is bound as described above and the Ph2POPPh2 is a bridging ligand. Reaction (1:1) of AAA with [RhCl(PPh3)3] led to the formation of [RhCl(AAA)(PPh3)]; anhydride coordination is as above and the phosphorus atoms are mutually trans. This complex is, however, found to revert back to [RhCl(PPh3)3] on standing. The (1:1) reaction with VAA produces [RhC1(PPh3) (Ph2PO2CCH = CHMe)] (Ph2PO2CCH=CHMe = CAA), an example of a metal promoted double bond migration. Subsequent study shows that at ambient pressure and temperature this complex (with 3 butenoic, oleic and hexa-4-enoic acids) is involved in stoichiometric and not catalytic reactions. [RhCl(CAA)(PPh3)] exhibits fluxionality at room temperature, 31p and 1H n.m.r, studies on this complex (223-263K) and on [Rh(CAA)(O2CCH=CHMe)(PPh3)] (298K) has determined the fluxionality to be a fast exchange between the cis and trans forms and led to the calculation of the thermodynamic parameters for this process . The 1:2 mole reaction of [RhCl(PPh3)3] and AAA gives lRhCl(PPh3)(Ph2POPPh2)], which contains a chelate tetraphenyl diphosphoxane ligand (tpdp) formed via a metal promoted rearrangement of the AAA ligand. Subsequent reaction of this complex with TIPF6 results in [Rh(PPh3)2(tpdp)][PF6]. However if the [RhCl(PPh3)(tpdp)] complex is not isolated, then the major product is [Rh(PPh3)3(Ph3PCH2CH2CO2)][PF6]. Further tpdp complexes have been formed by refluxing Ph2PP(O)Ph2 with [RhCl(PPh3)3], [RuCl2(PPh3)4] and [OsCl2(PPh3)4] in THF. However the reaction of [RhCl(PPh3)3] with excess Ph2PP(O)Ph2 gives several products, one of which, namely [RhCl2((PPh2O)2)H(PPh2O)][HNEt3], has been crystallographically characterised. The reaction (1:1) of [RuCl2(PPh3)4] with Ph2PO2CCHCMe2 (DAA) produces [RuCl2(PPh3)2(DAA)], in which the mixed anhydride is bound via the phosphorus atom and the oxygen atom of the carbonyl group. The 1:1 mole reactions of CAA and AAA give similar complexes as minor products whilst the structure of the major product is, however, not known at this point in time. The 1:2 mole reaction was found to produce [RuCl2(tpdp)(AAA)(PPh3)] in which the mixed anhydride is bound via the phosphorus atom alone.

The first part of the Thesis describes the work carried out in a study of the thermal decomposition of n-propyl and n-fluoropropyl radicals. n-Propyl radicals were generated by the high temperature chlorination of propane. The chlorine atoms produced in this reaction can abstract a hydrogen atom from the primary position in the propane. The n-propyl radical thus formed can either react with molecular chlorine present in the system or, at the temperature used, decompose to form ethylene and a methyl radical. Approximate values for the rate parameters of this reaction were obtained. A competitive technique for obtaining the rate parameters for the thermal decomposition of n-fluoropropyl radicals relative to the decomposition of the n-propyl radical was developed. Unfortunately due to the rapid decomposition of the starting material: 2,2-difluoropropane it was not possible to carry out these experiments. During the course of this study kinetic data was obtained from the photolytic chlorination of propane, the thermal decomposition of n-propyl chloride and sec-propyl chloride and the competitive photolytic chlorination of propane and 2,2-difluoropropane. The second part of the thesis describes a study of the comparison of the gas phase hydrogen abstraction reactions of trifluoromethyl and methyl radicals in the gas phase with n-butane, n-butyl fluoride and 1,1,1-trifluoropentane. Trifluoromethyl radicals were generated by the photolysis of trifluoromethyl iodide. The relative selectivities of the radicals were obtained by the quantitative measurement of the iodides formed from the reaction of the alkyl radicals with trifluoromethyl iodide. Methyl radicals were generated by the photolysis of azomethane. The radicals thus formed abstracted hydrogen atoms from one of the four reaction sites within the substituted butanes. The reactions were carried out in the presence of methyl iodide which acted as a chain propagator, the alkyl radicals formed abstracting iodine from the methyl iodide. The quantitative measurement of the alkyl iodides thus formed enabled the relative selectivities of the methyl radicals to be established. The results obtained showed the effect of the substituents on the relative selectivities of the two radicals for the different reaction sites within the alkanes.

M.Sc. (Chemistry) / The isomerization of short chain olefins on a catalyst containing a H-X zeolite (HZ-1) produces mainly branched olefins at 400°C. At SASOL the catalyst is also used to reduce organic acids present in the feed. Amarked increase in the acid concentration over a period of time has been reported. Other impurities in the reactor feed include short chain alcohols, aldehydes and ketones. This study consisted of kinetic experiments which concentrated on the formation of acids from ketones and aldehydes during the isomerization of 1-hexene on 60/80 mesh HZ-1. The formation of acetic and propionic acid from methyl ethyl ketone was observed. It was also shown that n-butyrealdehyde forms formic acet ic, propionic and n-butyric acid at 400°C. The presence of n-buthanol during the reaction of methyl ethyl ketone enhanced the formation of acid. A supplementary study showed the formation of only acetic acid from acetone. The study of the formation of acids from a 5% methyl ethyl ketone/5% n-buthanol at 400, 300, 250, 200 and 150°C showed an overall decrease in the acid concentration with a lowering in temperature. These results showed the development of a definite maximum in the acid production. The formation of formic acid was also observed at 200 and 150°C. Amechanism for the formation of acids from ketones is proposed and discussed. Other than existing mechanisms this explains the formation of formic, acetic and propionic acid from methyl ethyl ketone. The mechanism includes Bronsted and Lewis acid sites. During this study a method was developed for the analysis of trace quantities of organic acids present in the reaction product. Ion exclusion chromatography was used for the quantitative determination of the different types of acids. Surface studies with nitrogen adsorptics showed a drastic decrease in the surface area during the reactions. Pore volume studies showed remarkably the loss of macropores' with a pore diameter bigger than 3,6 nm. Pikinometry showed the existance of micropores which were unaffected by the reactions. Aneutron activation analysis of HZ-l showed the presence of a great variety of transition elements mainly Scandium, Cobalt and Iron.

Current interest in metal-metal bonded systems has been largely confined to the synthesis of such compounds, and little is known of the chemical behaviour of the metal-metal bonds. One of the simplest systems to study was the tin-tin bond, and thus the additions of fluoro-olefins to hexamethylditin were examined. Such additions were found to occur readily under ultraviolet irradiation which suggests that the formation of (CH₃)₃Sn radicals is an important feature of the reaction mechanism. The formation of adducts such as (CH₃)₃Sn(CF₂CF₂)nSn(CH₃)₃ (n = 1 or 2) , (CH₃)₃SnCF₂CF(CF₃)Sn(CH₃)₃, (CH₃)₃Sn(CFHCF₂)nSn(CH₃) ₃ (n = 1 or 2), and (CH₃) ₃Sn(CH₂CF₂)nSn(CH₃)₃(n = 1 or 2) , as well as the occurrence of secondary reactions leading to products of the type (CH₃)₃Sn(CF₂CF₂)nH (n = 1,2, or 3), (CH₃) ₃SnCF₂CF(CF₃)H, and other analogous compounds are discussed. The (CH₃)₃Sn radical was found to have nucleophilic character, and to attack exclusively on the group marked with an asterisk in the following olefins: [ Formulas omitted ]. The factors responsible for the orientation of such unsymmetric olefins with respect to the (CH₃)₃Sn radical are considered. The compound (CH₃)₃Sn-Mn(CO)₅, containing a mixed metal-metal bond, was also shown to be very reactive, but to behave differently toward a variety of olefins. A two-carbon insertion into the tin-manganese bond was readily achieved by the reaction with tetrafluoroethylene at 50° under ultraviolet irradiation, which again might suggest that a free-radical mechanism is involved. Two interesting dimers, i.e., the "boat and chair" forms of [CF₂=CFMn(CO) ₄] ₂, containing both σ- and π-bonds were formed, presumably through the decomposition of the adduct (CH₃)₃SnCF₂CF₂Mn(CO)₅. With trifluoroethylene, neither adduct nor dimer is obtained but the novel fluorovinyl-transition metal compounds cis- and trans-(CFH=CF)Mn(CO)₅ were formed. When reacted with trifluorochloroethylene, CF₂=CFCOMn(CO)₅ was predominantly obtained, as well as cis- and trans-(CFCl=CF)Mn(CO)₅ in small yields. The reaction with ethylene caused the cleavage of the manganese-carbonyl bond rather than the tin-manganese bond, forming (CH₃) ₃Sn-Mn(CO) ₄(π-C₂H₄) . The catalytic activity of (CH₃) ₃Sn-Mn(CO) ₅ in the hydrogenation of ethylene was also examined. Detailed spectroscopic studies were made for the products obtained in the pure state. / Science, Faculty of / Chemistry, Department of / Graduate

Chemical reaction fouling is one of several categories of fouling of heat exchangers. It is encountered mostly in petroleum, petrochemical, and food processing industries, where it results in severe economic penalties. Olefins have been associated with fouling during heating of organic mixtures, and gum formation during storage and use of hydrocarbon fuels. In this work, thermal fouling studies are reported for a number of olefins, present at 10 % wt. in kerosene, undergoing sensible heating in the liquid phase at relatively high heat fluxes. Experimental work was done on an available fouling rig consisting of an annular probe and a coiled wire probe mounted in parallel. The annular probe with its heated central core operated in turbulent flow whilst the coiled wire, with flow normal to it, was in the laminar flow regime. Runs were conducted both under oxygenated (air-saturated) and deoxygenated conditions. The range of bulk temperatures was from 70 - 85 ℃, the initial wall temperatures were 180 - 205 °C, with a system pressure of 410 kPa (abs.). The range of heat fluxes was 150 - 350 kW/m². Only minor differences were noted between the extent or rate of fouling on the two different probes. Runs at heat fluxes below 180 kW/m² and bulk temperatures below 80 °C generally showed no measurable fouling with any of the olefins tested. Linear and falling rate fouling curves were observed at more severe conditions over 45 hours of typical runs. Under air saturated conditions, straight chain terminal olefins of C₈ - C₉ showed little or no measurable fouling. The longer chain length hexadecane-1, showed a significant increase in fouling. Moderate fouling was observed for 4-vinylcyclohexene. The cyclic olefins, dicyclopentadiene and indene, yielded the greatest R[formula omitted] values, being about 30 - 50 times those of the straight chain terminal olefins. Under deoxygenated conditions, typical R[formula omitted] values were a factor of about 30 below the corresponding values for air saturated conditions. R[formula omitted] generally increased with increasing heat flux. Where the antioxidant initially present in the olefin was not removed before use, very little fouling occurred. The effects of deoxygenation, heat flux and species effects are discussed and a probable fouling mechanism involving formation of polymeric peroxides by autoxidation of the olefins suggested. The fouling rates over the linear portions of the fouling curves have been calculated and the deposit thermal conductivity based on the maximum fouling resistance and deposit thickness have been estimated. Analyses of selected deposits have been presented and compared with both theoretical calculations for the expected polymeric peroxides and values in the literature. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Heterocycles are privileged structural motifs found in many natural products and biologically active compounds. Given the prevalence of this structural unit, there has been considerable interest and challenge in developing methods for construction optically pure heterocycles in organic synthesis and pharmaceutical chemistry. The skeleton of hydronaphthalene and indole are pervasive structural motifs in the pharmaceutical drugs that exhibit various bioactivities. This dissertation is mainly focused on the development of transition-metal-catalyzed asymmetric functionalization of alkenes, including the hydroselenation and hydroamination of various oxa/azabicyclic olefins for the synthesis of bioactive compounds and structural modification of oleanolic acid. An efficient rhodium catalytic system consisting of Rh(COD)2OTf/(S)-xyl-Binap, and n-Bu4NI was developed for the asymmetric hydroselenation of various oxa/azabicyclic olefins with diaryl diselenides instead of the unstable, malodorous selenol compounds. Under these reaction conditions, a wide range of heterobicyclic alkenes produced selenol containing hydronaphthalene derivatives in high yields (up to 96%) along with excellent enantioselectivities (up to 97%), overcoming the self- promoted racemic hydroselenation. The exo-configuration of the exclusive addition product was confirmed by X-ray crystal structure analysis. The strategy has also been applied to the kinetic resolution of unsymmetric oxabenzonorbornadiene. Further, these selenium compounds can catalyze the oxidative coupling reaction of 2-naphthols. Then, for the synthesis of trans 1-indolyl dihydronaphthalenols, a highly enantioselective Rh/Pd dual-metal sequentially catalytic system was revealed through intermolecular and intramolecular cascade hydroamination in the reaction of oxabenzonorbornadienes with 2-alkynylanilines. The exclusive trans-configuration of 1-(2-phenyl)indolyl dihydronaphthalenol was identified by X-ray crystal analysis. Various substituents, such as aryl, heteroaryl, alkyl, and silyl groups on alkynyl starting material can be used as compatible nucleophiles in the reaction to give excellent iii enantiomeric excesses (up to 99%) with good yields (up to 88%) under mild conditions. The reaction can be performed on a gram scale, while the indole derivatives could be transformed at the hydroxyl and indolyl funtionalities. The in silico and in vitro screening showed that the novel 1-indolyl dihydronaphthalenol products can serve as potential lead compounds for treating inflammation disease. At last, a series of functional groups, including carboxyl, phosphate, sulfone, triazole, tertiary amine, and glycosyl have been incorporated into oleanolic acid to improve its water solubility. A wide range of their derivatives have been obtained, and it was found that carboxyl salt, phosphate salt, and sulfonate salt contribute to the increase of the solubilities in water; up to 8 g/L was gained for carboxylate salt, which also provides the possibility to improve the bioavailability of these compounds