No / A fast, complete and clean conversion of thioglycosides into glycosyl sulfones under mild acidic conditions is described, using the HOF·CH3CN complex at room temperature. This methodology affords glycosyl sulfones in high yields and in excellent purity.

Industrial catalysts used in commercial processes for the production of maleic anhydride are mainly Vanadium Phosphorous Oxide (VPO) catalysts. The VPO catalyst used is Vanadyl Pyrophosphate (VO)2P207 made from its precursor Vanadium Phosphorous Hemi-Hydrate VOHP04.O.5H20 in an non-aqueous medium. In order for the VPO catalyst to perform optimally, a metal promoter, Ru, was selected as the doping agent in this study. Four catalysts of different metal doping concentrations (undoped, 0.2%, 0.6% and 1%) were subjected to the oxidation of n-butane. Promoters are added to facilitate the oxidation of n-butane to maleic anhydride. n-Butane gas is now being used in many industrial processes, in fixed bed reactors to convert the gas to maleic anhydride. Catalysts were calcined under high temperatures under a nitrogen atmosphere. It was found that with an increase in reaction temperature, there was an increase in conversion of n-butane to maleic anhydride. Selectivity of the product also showed an increase with an increase in temperature at a Gas Hourly Space Velocity (GHSV) of 1960-2170hr-1. Catalysts were characterized using different techniques such as Electron Dispersive X-Ray Spectroscopy, Inductively Coupled Plasma-Atomic Emission Spectroscopy, Fourier Transform - Infra Red, Average Oxidation State, Brunauer Emmett and Teller (surface area), X-Ray Diffraction and Scanning Electron Microscopy. The 0.6% Ru promoted VPO catalyst showed to be most effective in terms of conversion, selectivity and yield, at a temperature of 450°C as compared to the other catalysts studied. The catalysts degenerated after being subjected to higher temperatures. The selectivity obtained by this catalyst was at 70.2% and the yield obtained was 37%. This study showed that with an increase in Ru up to a certain concentration (0.6%), an increase in selectivity and yield was observed, thereafter, with additional Ru doping, a decrease in selectivity and yield was obtained. / Thesis (M.Sc.)-University of Natal, 2003.

Thesis (Master of Engineering in Chemical Engineering)--Cape Peninsula University of Technology, 2019. / A shortage of water has resulted in the need to enhance the quality of wastewater that is released into the environment. The advanced oxidation process (AOP) using heterogeneous catalysis is a promising treatment process for the management of wastewater containing recalcitrant pollutants as compared to conventional processes. As AOP is a reliable wastewater treatment process, it is expected to be a sustainable answer to the shortage of clean water. AOP using heterogeneous catalysis based on Co3O4 particles and PMS, in particular has been found to be a powerful procedure for the degradation and mineralization of recalcitrant organic contaminants. In addition, due to the growing application of Co3O4 in lithium batteries, large quantities of these particles will be recovered as waste from spent lithium batteries, so there is a need to find a use for them. Although this method has received some promising feedback, challenges still need to be addressed, such as the toxicity of cobalt particles, the poor chemical and thermal stability and particle aggregation, and the prompting of lower catalytic efficiency in long haul application. Furthermore, the removal of the catalyst after the treatment of pollutants is also an issue. In order to be applicable, a novel catalyst must be produced requiring the combination of Co3O4 with a support material in order to inhibit cobalt leaching and generate better particle stability. From the available literature, TiO2 was found to be the best support material because it not only provides a large surface area for well dispersed Co3O4, but it also forms strong Co-O-Ti bonds which greatly reduced cobalt leaching as compared to other support materials. Moreover, it also greatly encourages the formation of surface Co–OH complexes, which is considered a crucial step for PMS activation. Therefore, the issues cited above could be avoided by producing a Co3O4/TiO2 heterojunction catalyst.

Kwong Tsz Yan Alex. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 77-84). / Abstracts in English and Chinese. / Abstract --- p.i / Declaration --- p.iii / Acknowledgement --- p.iv / Table of contents --- p.v / List of tables --- p.ix / List of figures --- p.x / Chapter Chapter One : --- Introduction --- p.1 / Chapter 1.1 --- The outbreak of SARS --- p.1 / Chapter 1.2 --- Characteristics of triclosan --- p.2 / Chapter 1.3 --- Environmental fate of triclosan --- p.3 / Chapter 1.4 --- Treatment methods for triclosan --- p.5 / Chapter 1.5 --- Ti02 photocatalysis --- p.6 / Chapter 1.6 --- Addition of hydrogen peroxide to the photocatalytic system --- p.9 / Chapter 1.7 --- Gas chromatography/ ion trap mass spectrometry analysis --- p.10 / Chapter 1.8 --- Scope of work --- p.11 / Chapter Chapter Two : --- Experimental --- p.13 / Chapter 2.1 --- Chemical reagents --- p.13 / Chapter 2.2 --- Photocatalytic experiments --- p.14 / Chapter 2.3 --- "Analysis of 2,8-DCDD and triclosan by GC/ITMS" --- p.15 / Chapter 2.4 --- Optimization of GC/ITMS conditions --- p.17 / Chapter 2.5 --- Analysis of other reaction intermediates by GC/MS (full scan mode) --- p.18 / Chapter 2.6 --- "Analysis of 2,4-dichlorophenol and triclosan by GC/MS (SIM mode)" --- p.20 / Chapter 2.7 --- Effect of hydrogen peroxide concentration on triclosan degradation --- p.20 / Chapter 2.8 --- Determination of total organic carbon (TOC) removal --- p.21 / Chapter 2.9 --- UV-Visible spectrometry --- p.21 / Chapter Chapter Three : --- Results --- p.22 / Chapter 3.1 --- Selection of precursor ions for GC/ITMS analysis --- p.22 / Chapter 3.2 --- Optimization of GC/ITMS conditions --- p.25 / Chapter 3.3 --- "Analysis of 2,8-DCDD and triclosan by GC/ITMS" --- p.27 / Chapter 3.4 --- "Analysis of 2,4-dichlorophenol and triclosan by GC/MS (SIM mode)" --- p.29 / Chapter 3.5 --- "Quantitative measurement of 2,8-DCDD in UV irradiated samples" --- p.31 / Chapter 3.6 --- Photocatalytic oxidation of triclosan by UV at 365nm --- p.33 / Chapter 3.7 --- TOC removal in triclosan degradation --- p.35 / Chapter 3.8 --- Identification of intermediates in photocatalytic oxidation of triclosan --- p.36 / Chapter 3.9 --- Quantitative measurement of the intermediates in photocatalytic oxidation of triclosan --- p.41 / Chapter 3.10 --- Effect of hydrogen peroxide concentration on triclosan degradation --- p.43 / Chapter 3.11 --- Effect of hydrogen peroxide concentration on TOC removal --- p.46 / Chapter 3.12 --- "Effect of hydrogen peroxide concentration on 2,4-dichlorophenol generation during triclosan degradation" --- p.47 / Chapter 3.13 --- "Photocatalytic degradation of 2,4-dichlorophenol" --- p.49 / Chapter 3.14 --- "Identification of intermediates in photocatalytic oxidation of 2,4-dichlorophenol" --- p.50 / Chapter 3.15 --- "Quantitative measurement of the intermediates in photocatalytic oxidation of 2,4-dichlorophenol" --- p.54 / Chapter Chapter Four : --- Discussions --- p.56 / Chapter 4.1 --- "Photochemical conversion of triclosan to 2,8-DCDD" --- p.56 / Chapter 4.2 --- Proposed mechanism of triclosan degradation --- p.57 / Chapter 4.3 --- "Proposed mechanism of 2,4-dichlorophenol degradation" --- p.63 / Chapter 4.4 --- TOC removal in triclosan degradation --- p.65 / Chapter 4.5 --- Effect of hydrogen peroxide concentration on photocatalytic oxidation of triclosan --- p.65 / Chapter 4.6 --- "Adverse environmental and human health effects of 2,8-DCDD" --- p.69 / Chapter 4.7 --- "Adverse environmental and human health effects of 2,4-dichlorophenol" --- p.71 / Chapter 4.8 --- "Discharge limitations for 2,4-dichlorophenol" --- p.73 / Chapter Chapter Five : --- Conclusions --- p.75 / References --- p.77

The physiologically important free radicals, nitrogen monoxide and superoxide, can combine to form the reactive intermediate peroxynitrite. Peroxynitrite can react with proteins and their constituent amino acids, such as tyrosine, resulting in protein peroxidation, oxidation and nitration. The nitration of proteins, assessed by the analysis of 3-nitrotyrosine, is a proposed index of pathophysiological activity of peroxynitrite. The aim of the work was to investigate the reaction products between peroxynitrite and protein, develop an assay for 3-nitrotyrosine and measure its levels in biological samples. To study the amino acid products arising from the reaction of peroxynitrite and protein, both liquid chromatography (LC) and gas chromatography (GC) combined with mass spectrometry (MS) were adopted. Approaches to 3-nitrotyrosine assay development were first, to take advantage of the intrinsic sensitivity of electron capture negative ionization GC-MS. Secondly, to avoid possible artefactual problems associated with the derivatisation step in GC-MS, an assay for 3-nitrotyrosine based on combined LC-MS-MS was developed. When a selection of peptides was exposed to peroxynitrite under physiological conditions in vitro, the hydrolysis products showed that 3-nitrotyrosine was the major product. Detectable minor products were 3,5-dinitrotyrosine and DOPA. The GC-MS assay was found to be fraught with difficulty due to artefactual formation of 3-nitrotyrosine. In order to quantify and correct for artefact formation, this complication was approached by incorporating a second isotopomer. This method, however, was confounded by large errors that reduced the overall sensitivity. Either negative or zero levels of endogenous 3-nitrotyrosine were found in tested samples after correction for artefact formation. The LC-MS-MS assay was then used to analyse 3-nitrotyrosine levels in a range of biological samples, including human plasma from healthy volunteers, synovial fluid samples from arthritis patients and tissue extracts from a mouse model of amyotropic lateral sclerosis. In contrast to published data, 3-nitrotyrosine levels were found to be below the limit of detection (1 pg/????L, 10 pg o/c) for all samples - a result somewhat consistent with the negative GC-MS data. It is suggested that the high 3-nitrotyrosine levels previously reported in the literature might reflect artefactual generation of 3-nitrotyrosine and that other approaches to assessing pathophysiological nitration should be sought in future.

In this thesis, a combination of laboratory experimentation under well defined conditions coupled with a kinetic modelling approach is used to verify the existence and respective kinetic rates of previously unconfirmed or postulated mechanisms that drive and limit dark Fenton (Fe(II)/H2O2) - mediated As(III) oxidation at pH 3 and 8 and dark Cu(II) - H2O2 - mediated As(III) oxidation at pH 8. Dark Fenton - mediated oxidation of As(III) at pH 3 is first examined and the effects of the variation in the concentration of reactants (As(III), Fe(II) and H2O2), oxygen, phosphate and organics (2 - propanol, formate, and citrate) are reported and analysed. The kinetic models developed for these systems show high applicability to full scale water treatment application and key mechanistic findings include the significance of the cycling of Fe(II) / Fe(III) via HO2 ???/O2 ??????, the effects of As(IV) termination reactions in the absence of oxygen and the retarding effects of phosphate due to the postulated formation of a Fe(III) - phosphate complex (at a derived rate constant of 2.2 x 106 M-1s-1, that also appears to have negligible kinetic activity in terms of reduction to Fe(II) by HO2 ???/O2 ??????). The work also demonstrates the significance of the free radical by products of formate and citrate oxidation by ???OH (HCOO???/CO2 ?????? and 3HGA???2???). The examination of the dark Cu(II) - H2O2 - mediated oxidation of As(III) at pH 8 with variation in the concentration of reactants (As(III), Fe(II) and H2O2), carbonate and organics (2 - propanol, formate and citrate) demonstrated for the first time the high applicability of this system to the pre - oxidation of As(III) in water treatment and mechanistically that ???OH and CO3 ?????? are the dominant As(III) oxidants in this system. The As(III) oxidant CO3 ??????, is suggested to be generated by the interaction of ???OH and O2 ?????? with the carbonate matrix, at the respective rate constants of 4.9 x 107 M-1s-1 and 5.5 x 106 M-1s-1. Examination of the dark Fenton - mediated oxidation of As(III) at pH 8 and the effects of variation in the concentration of reactants (As(III), Fe(II) and H2O2), carbonate, organics (2 - propanol, formate and citrate) and Cu(II) demonstrates the varied potential mechanistic pathways in relation to the generation of As(III) oxidants from the Fenton reaction, Fe(II) + H2O2 such as Fe(IV) and CO3 ?????? and the previously dismissed ???OH, due to the presence of Fe(II) - citrate complexes. This work also demonstrates and models the enhancement of As(III) oxidation in the presence of an additional transitional metal ion, Cu(II).

C3H6 oxidation over a Pt/Al2O3 catalyst with or without NOx present was investigated. In particular, its reaction mechanism was studied using diffuse reflectance infrared spectroscopy (DRIFTS), a reactor system designed for monolith-supported catalysts and a micro-reactor system designed for powder catalysts referred to as CATLAB. These experiments reveal that C3H6 oxidation is inhibited by the presence of NO, NO oxidation is inhibited by the presence of CeH6, and that adsorbed NOx can react with gas phase C3H6. DRIFTS and CATLAB results confirm the reaction between C3H6 and nitrates, which are formed during NOx adsorption, with linear nitrites observed as reaction products. Therefore, a reaction route is proposed for C3H6 oxidation in the presence of NOx, namely, nitrates acting as oxidants. Using NO2 instead of NO, or using a high NOx/C3H6 ratio, which is beneficial for nitrate formation, favors this reaction pathway. Data also showed that Pt is required for this reaction, which suggests the nitrates in proximity to the Pt particles are affected/relevant. Reaction kinetics studies of C3H6 oxidation over Pt/Al2O3 and Pt/SiO2 catalysts were performed in CATLAB using a temperature-programmed oxidation method with different oxidants: O2, NO2 and nitrates. The reaction kinetics of these possible reactions were compared in order to determine which reaction is more important. NOx adsorption does not occur on the SiO2 surface so the reaction between C3H6 and NO2 could be isolated and the effect of nitrates could be observed as well when compared to the results from Pt/Al2O3. The Pt dispersions were determined using H2 chemisorption and were 1.3 and 1.6% for Pt/Al2O3 and Pt/SiO2, respectively. C3H6 oxidation starts at a lower temperature with O2 than with NO2 but the activation energy was lower with NO2. This gives indication that hydrocarbons must be activated first for NO2 to be favored in hydrocarbon oxidation. When the experiment was done with C3H6 and nitrates, the reaction did not occur until NOx started to desorb from the catalyst at higher temperatures, when nitrates become unstable and decompose. Therefore, O2 was added to the system and the reaction began at even lower temperature than with just C3H6 and O2. This proved that hydrocarbons need to be activated in order for surface nitrates to affect C3H6 oxidation and this reaction also resulted in a lower activation energy than with just C3H6 and O2. Nitrate consumption was also observed as less NOx desorbed from the catalyst at the later stage of the temperature ramp compared to the amount desorbed when the catalyst was not exposed to C3H6.

Nitroxide radical groups grafted on silica have been synthesized. The catalytic oxidation of alcohols to aldehydes and ketones using the nitroxide radical groups as a catalyst was also investigated. The results of scanning electron microscopy, infrared spectroscopy, and X-ray photoelectron spectroscopy confirmed that the nitroxide radical groups are successfully grafted onto silica. The yield of the catalytic oxidation using the catalysts is higher than 99%. The catalysts are easily recovered. Furthermore, the reused catalysts still keep high performance in the catalytic oxidation.

Selective oxidations are important for the functionalization of compounds in organic synthesis and chemical industry. Using O2 as a terminal e- acceptor would be ideal because it is cheap and environmentally friendly, but aerobic oxidations are often prone to unselective free radical autoxidation. Recently developed palladium catalysts use O2 as a selective multi-electron oxidant for various organic transformations. Although these methods are powerful and sophisticated, the lower cost of base metals makes them attractive as potential alternatives. The challenge is to develop methods for effecting multi-electron transformations at metals that typically prefer one electron changes. To this end, the development of manganese(III) complexes containing redox-active ligands as catalysts for selective oxidase-type oxidation of organic substrates was pursued. Bis(tetrabromocatecholato) manganese(III) complexes were shown to aerobically oxidize catechols to form quinones and H2O2. This reactivity was extended to other alcohol and amine substrates. In these reactions, the non-innocent tetrabromocatecholate ligands may impart a multi-electron character to the metal. To directly probe the intermediacy of ligand-centered radicals in catalytic turnover, a series of structurally similar manganese(III) complexes with aminophenol-derived ligands were prepared and characterized. The capacity of these ligands to undergo low-energy redox changes, allowed for isolation of an electron transfer series spanning two redox states without a change in oxidation state at the metal center. The ligand-centered redox events were a key feature in aerobic homocoupling of Grignard reagents.

C3H6 oxidation over a Pt/Al2O3 catalyst with or without NOx present was investigated. In particular, its reaction mechanism was studied using diffuse reflectance infrared spectroscopy (DRIFTS), a reactor system designed for monolith-supported catalysts and a micro-reactor system designed for powder catalysts referred to as CATLAB. These experiments reveal that C3H6 oxidation is inhibited by the presence of NO, NO oxidation is inhibited by the presence of CeH6, and that adsorbed NOx can react with gas phase C3H6. DRIFTS and CATLAB results confirm the reaction between C3H6 and nitrates, which are formed during NOx adsorption, with linear nitrites observed as reaction products. Therefore, a reaction route is proposed for C3H6 oxidation in the presence of NOx, namely, nitrates acting as oxidants. Using NO2 instead of NO, or using a high NOx/C3H6 ratio, which is beneficial for nitrate formation, favors this reaction pathway. Data also showed that Pt is required for this reaction, which suggests the nitrates in proximity to the Pt particles are affected/relevant. Reaction kinetics studies of C3H6 oxidation over Pt/Al2O3 and Pt/SiO2 catalysts were performed in CATLAB using a temperature-programmed oxidation method with different oxidants: O2, NO2 and nitrates. The reaction kinetics of these possible reactions were compared in order to determine which reaction is more important. NOx adsorption does not occur on the SiO2 surface so the reaction between C3H6 and NO2 could be isolated and the effect of nitrates could be observed as well when compared to the results from Pt/Al2O3. The Pt dispersions were determined using H2 chemisorption and were 1.3 and 1.6% for Pt/Al2O3 and Pt/SiO2, respectively. C3H6 oxidation starts at a lower temperature with O2 than with NO2 but the activation energy was lower with NO2. This gives indication that hydrocarbons must be activated first for NO2 to be favored in hydrocarbon oxidation. When the experiment was done with C3H6 and nitrates, the reaction did not occur until NOx started to desorb from the catalyst at higher temperatures, when nitrates become unstable and decompose. Therefore, O2 was added to the system and the reaction began at even lower temperature than with just C3H6 and O2. This proved that hydrocarbons need to be activated in order for surface nitrates to affect C3H6 oxidation and this reaction also resulted in a lower activation energy than with just C3H6 and O2. Nitrate consumption was also observed as less NOx desorbed from the catalyst at the later stage of the temperature ramp compared to the amount desorbed when the catalyst was not exposed to C3H6.