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.

This thesis is concerned with the reactions of sulfur-centred radicals and alkynes. The first objective of this work was to extend the scope of “self-terminating radical cyclisations” to sulfur-centred radicals, such as thiyl radicals. Preliminary experiments revealed that the reaction of thiyl radicals with alkynes was sensitive to residual oxygen. In the absence of oxygen, the reactions of photochemically generated phenylthiyl radicals with cyclodecyne (1) resulted in three isomeric sulfides, which were identified through a combination of techniques. (1S,6S)-2-phenylthiobicyclo[4.4.0]decane (trans-49a, unknown stereochemistry at C2) was identified by synthesis of an authentic sample, while the structure of (1S,2R,6S)-2-phenylthiobicyclo[4.4.0]decane (cis-49a1) was determined by X-ray analysis of the corresponding crystalline sulfone, cis-69. The third sulfide, (1S,2S,6S)-2-phenylthio-bicyclo[4.4.0]decane (cis-49a2), was assigned based on computational studies. / In addition, the reactions of benzylthiyl, tert-butylthiyl and allylthiyl radicals with cyclodecyne (1) were investigated. Various sources of thiyl radical generation were utilized, such as the photolysis of disulfides and thiols, hydrogen atom abstraction of thiols using radical initiators, as well as thiol autoxidation in the presence of oxygen. The radical cascade initiated by the addition of thiyl radicals to alkyne 1 was typically terminated by either reduction or disproportionation, whereas “self-termination” was only observed in one particular instance where the tert-butylthiyl radical was generated by autoxidation. However, this was only a minor pathway. / The second objective of this work was to investigate the reactions of thiyl radicals with alkynes in the presence of oxygen. For this purpose, phenylthiyl radicals were generated in the presence of diphenylacetylene (89) and molecular oxygen. Benzil (91), an α-diketone, and 1,2-diphenyl-2-(phenylthio)ethanone (93), an α-ketosulfide, were formed. The novel thiyl radical-mediated oxidation of diphenylacetylene to benzil mediated proceeds under mild and metal-free conditions, using various methods of thiyl radical generation. The product ratio of diketone to ketosulfide varied with the reaction conditions. Under photochemical conditions, benzil was formed but its photodegradation was also observed. Using autoxidation, moderate to good yields of both diketone 91 and ketosulfide 93 were obtained, although the product ratios varied with solvent and reaction conditions. Diketone 91 was the major product when the thiyl radical was generated electrochemically. Following investigation of the reaction mechanism using experimental and computational studies, the phenylthiyl peroxyl radical was identified as the key reactive intermediate. This represents the first synthetic application of thiyl peroxyl radicals. / Using autoxidation conditions, the oxidation was explored using substituted aromatic thiyl radicals, e.g. 2,6-dimethylbenzene, 2,4,6-tri-tert-butylbenzene, 4-methoxybenzene and 4-nitrobenzene thiyl radicals. Except for the case of 4-methoxybenzene thiyl radicals, where generation of the thiyl radicals was inefficient, diketone 91 was formed as the dominant product. This oxidation of alkynes to ketones, via thiyl radical-mediated activation of oxygen, was then applied to cyclodecyne (1). Bicyclic ketones 7/8 were found as the major products under photochemical conditions, while sulfides 152/trans-49a were the dominant products under autoxidation conditions. Bicyclic ketones 7/8 were formed due to the intramolecular radical processes directed by the transannular strain of the ten-membered carbon framework. Only trace amounts of the cyclic α-diketone 151 were detected under autoxidation conditions.

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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.

Thesis (Ph. D.)--Worcester Polytechnic Institute. / Keywords: hydrodechlorination; reaction kinetics; reaction steps; chlorinated compounds; Palladium catalysts. Includes bibliographical references.

Nuclear magnetic resonance (NMR) yields remarkably detailed structural information about virtually any molecule. However, its application to non-equilibrium systems is hampered by a lack of sensitivity. To increase the amount of signal that can be obtained from a NMR experiment, various hyperpolarization schemes have been previously introduced. One such technique is dynamic nuclear polarization (DNP), which can enhance NMR sensitivity by several orders of magnitude. The work detailed here focuses on the development of methods utilizing DNP to study non-equilibrium systems such as chemical and biochemical reactions in real-time. To work with hyperpolarized samples, we have designed and constructed a rapid injection and mixing system. This system allows samples to be transported between superconducting magnets used for polarization and for NMR spectroscopy in less than two seconds. Rapid transport is essential for successful use of samples with short spin-lattice relaxation times. For the study of reactions under non-equilibrium conditions, the system provides the additional capability for samples to be mixed with a second, unpolarized reagent. A chromogenic trypsin catalyzed ester hydrolysis reaction was used to validate the DNP-NMR technique as a tool for kinetic analysis. It is shown that the DNP-NMR method agrees with the conventional UV method within the uncertainty of the measurement. Hyperpolarization in this modality presents both challenges and opportunities, each of which motivate the development of new NMR techniques. In addition to the determination of kinetics, DNP-NMR is amenable to mechanistic analysis of a reaction. We have developed a technique based on selective inversion of spin-polarization, which allows for mapping of atoms between reactant and product of a reaction. This scheme was applied to a Grignard reaction, demonstrating applicability to organic reactions. Signal averaging, as it is applied for conventional multi-dimensional correlation spectroscopy cannot always be applied easily when using hyperpolarized sample. For the rapid measurement of heteronuclear correlation spectra, we have developed a technique utilizing the differential scaling of scalar coupling under off-resonance irradiation. Although DNP-NMR yields spectra of outstanding quality even with small quantities of sample, peak intensities are not quantitative. It is nevertheless possible to compare peak multiplets obtained from fractionally isotope labeled samples. Using biosynthetically labeled lipids from E. Coli cells, we showed that the resulting labeling patterns reflect their biosynthetic pathways. As a final case-study employing several of these newly developed methods, the uronate isomerase catalyzed isomerization of glucuronate into fructuronate was studied. The ability to follow the reaction in real-time while directly observing all anomeric forms of the reactant and product permits the independent determination of kinetics for each anomeric form of substrate and product. This study revealed the anomeric specificity of the enzyme.