Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains x, 225 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 113-119).

Thesis (Ph. D.)--University of Florida, 2004. / Title from title page of source document. Document formatted into pages; contains 79 pages. Includes vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1992. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.Sc. Chemistry)--University of Waikato, 2008. / Title from PDF cover (viewed September 18, 2008) Includes bibliographical references (p. 70-80)

No description available.

The competition between substitution (SN2) and elimination (E2) in nucleophilic reactions of alkyl halides has had a profound influence on the development of physical organic chemistry and remains an important testing ground for identifying reactivity patterns in gas-phase organic chemistry. Here, the competition between substitution and elimination, as well as the regioselectivity of E2 reactions have been examined in the gas phase. By doing so, the intrinsic reactivity patterns can be probed in the absence of solvation effects. The SN2 and E2 reactions of a large set of alkyl bromides with varying substitution patterns at the α- and β-carbons were studied in the gas phase using naphthoate and phenoxide-based dianion nucleophiles. The experiments were performed in a quadrupole ion trap mass spectrometer equipped with electrospray ionization. The experimental work was supported by calculations at the MP2/6-31+G(d,p)//MP2/6-31+G(d) level. The naphthoate is a weaker base and leads to more products from the SN2 pathway. In accord with generalizations from condensed-phase results, primary bromides generally prefer substitution pathways and secondary bromides prefer eliminations. In the gas phase, polarizability is more important, and the highest SN2 reactivity is observed when the β-carbon is 2° - steric crowding from β-substituents is not as significant for un-solvated nucleophiles. In addition, the data confirms that alkyl substituents at the β-carbon have a greater accelerating effect on E2 reactions than those at the α-carbon. Finally, computed data based on lowest enthalpy pathways provide poor descriptions of the reactions of the larger alkyl bromides and are skewed toward crowded systems that offer stabilizing, nonbonded interactions at the expense of conformational freedom. An investigation of regiochemical preferences of E2 reactions was also explored by synthesizing and analyzing the product distributions of a set of deuterium-labeled compounds capable of Saytzeff and Hofmann elimination. Gas-phase reactions of these substrates with dianion nucleophiles indicate that as expected, there is a preference for the Saytzeff product, which is also preferred in solution. This is the first study of E2 regioselectivity in the gas phase for a simple alkyl system.

Persistent organic pollutants are a well-known threat to the environment. Substances such as polycyclic aromatic hydrocarbons and chlorinated organic compounds in contaminated soil and groundwater can have severe and long-lasting effects on health in animals and humans. There is an urgent need for the development of safe technologies for their effective removal. Originally developed for mineral processing, mechanical treatment by ball milling is an extremely versatile technique for the degradation of toxic compounds. Reactive milling can rapidly destroy organic compounds without producing hazardous wastes. Complete breakdown of the organic molecules is achieved after relatively short milling times. Successful tests were conducted on polychlorobiphenyls (PCBs), DDT, DDD, DDE, Dieldrin and hexachlorobenzene with a conversion yield in the of greater than 99% (Hall et al., 1996; Monagheddu et al., 2000; Zhang et al., 2001; Zhang et al., 2002; Tanaka and Zhang, 2003; Pizzigallo et al., 2004; Nomura et al., 2005; Bellingham, 2006).In this study reactive ball milling was used to investigate the destruction of two classes of persistent organic pollutants environmental contaminants. The compounds studied are either known environmental pollutants or simple analogues. These were chosen as being representative of pollutants to investigate the pathway using ball milling destruction and in most cases were relatively small molecules so that the intermediates could be more easily identified. The first class of compounds was polycyclic aromatic compounds. Some smaller members of this class such as naphthalene, anthracene were investigated. The second class of compounds were some analogues of environmentally hazardous hydroxylated and halogenated compounds such as chloronaphthalene, bromonaphthalene, 1- naphthol, 2-naphthol and pentachlorophenol under reactive milling using GCMS analysis of the degradation pathway. Destruction efficiencies greater than 99% have been achieved for a number of organic compounds. Several different intermediates have been identified during the milling degradation. There was also some evidence from this study that halogens could be transferred between compounds during milling. The final products of the milling destruction of these compounds are an amorphous carbon residue and inorganic chloride or bromides. It was proposed that large amounts of halogens could be found however the results showed that small amounts detected. At early stages of milling a number of intermediate breakdown products were detected which were destroyed on extended milling. The core objective of this research was to clarify the reaction mechanisms pathways used of more complex polycyclic aromatic hydrocarbons and aromatic organ halogen compounds. This study is a part of a long-term research project on the destruction of toxic organic compounds by reactive milling.

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 165-172). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 165-172). Also available on the Internet.

Persistent organic pollutants are a well-known threat to the environment. Substances such as polycyclic aromatic hydrocarbons and chlorinated organic compounds in contaminated soil and groundwater can have severe and long-lasting effects on health in animals and humans. There is an urgent need for the development of safe technologies for their effective removal. Originally developed for mineral processing, mechanical treatment by ball milling is an extremely versatile technique for the degradation of toxic compounds. Reactive milling can rapidly destroy organic compounds without producing hazardous wastes. Complete breakdown of the organic molecules is achieved after relatively short milling times. Successful tests were conducted on polychlorobiphenyls (PCBs), DDT, DDD, DDE, Dieldrin and hexachlorobenzene with a conversion yield in the of greater than 99% (Hall et al., 1996; Monagheddu et al., 2000; Zhang et al., 2001; Zhang et al., 2002; Tanaka and Zhang, 2003; Pizzigallo et al., 2004; Nomura et al., 2005; Bellingham, 2006).In this study reactive ball milling was used to investigate the destruction of two classes of persistent organic pollutants environmental contaminants. The compounds studied are either known environmental pollutants or simple analogues. These were chosen as being representative of pollutants to investigate the pathway using ball milling destruction and in most cases were relatively small molecules so that the intermediates could be more easily identified. The first class of compounds was polycyclic aromatic compounds. Some smaller members of this class such as naphthalene, anthracene were investigated. The second class of compounds were some analogues of environmentally hazardous hydroxylated and halogenated compounds such as chloronaphthalene, bromonaphthalene, 1- naphthol, 2-naphthol and pentachlorophenol under reactive milling using GCMS analysis of the degradation pathway. Destruction efficiencies greater than 99% have been achieved for a number of organic compounds. Several different intermediates have been identified during the milling degradation. There was also some evidence from this study that halogens could be transferred between compounds during milling. The final products of the milling destruction of these compounds are an amorphous carbon residue and inorganic chloride or bromides. It was proposed that large amounts of halogens could be found however the results showed that small amounts detected. At early stages of milling a number of intermediate breakdown products were detected which were destroyed on extended milling. The core objective of this research was to clarify the reaction mechanisms pathways used of more complex polycyclic aromatic hydrocarbons and aromatic organ halogen compounds. This study is a part of a long-term research project on the destruction of toxic organic compounds by reactive milling.