Physical Sciences and Mathematics Commons^™

Scope And Mechanistic Studies Of Ruthenium Catalyzed C-N Bond Activation Reactions, Pandula Taepith Kirinde Arachchige

Dissertations (1934 -)

Primary aliphatic amines which are ubiquitous in natural products, traditionally considered as inert to substitution reactions. Recent studies clearly demonstrated that the aliphatic deaminative coupling chemistry can be used to make valuable scaffolds through C–N bond activation on transition metal complexes. The catalytic system generated in situ from the tetranuclear Ru–H complex with a catechol ligand (2-9/2-16) and independently synthesized ruthenium catecholate complex 2-11 was found to be effective for the direct deaminative coupling of primary amines. The catalytic system formed in-situ from the reaction of cationic Ru–H complex 2-10 with 3,4,5,6-tetrachloro-1,2-benzoquinone 2-12 was found to mediate a regioselective deaminative …

A Novel Method For Synthesis Of Hydroxytyrosol, Emmanuel Onobun

Electronic Theses and Dissertations

Hydroxytyrosol, 3,4-dihydroxyphenolethanol, a naturally occurring polyphenol most common in olive tree (Olea europaea), is one of the most effective member of the polyphenols family, because of its remarkable antioxidant activity, its ability to inhibit oxidation of low density lipids (LDL), and its protection against DNA oxidative damage. Hydroxytyrosol, which is widely used in cosmetics and food supplements industries, can be purchased as an olive oil extract that contains low concentration of hydroxytyrosol besides other polyphenols. The price and low natural abundance of hydroxytyrosol make alternative synthetic sources very attractive. In this research, a novel method for the synthesis of pure …

A Chlorine-Free Protocol For Processing Silicon, Germanium, And Tin, Michael J. Krause

Electronic Thesis and Dissertation Repository

Replacing molecular chlorine and hydrochloric acid with less energy- and risk-intensive reagents would dramatically improve the environmental impact of metal manufacturing at a time when demand for metals is rapidly increasing. Germanium and tin are classified as “critical” elements based on growing demand for these elements in technological applications, lack of suitable substitutes, and, for germanium, high dispersion in the environment making extraction of the element process-intensive. This thesis describes a recyclable quinone / catechol redox platform that provides an innovative replacement for elemental chlorine and hydrochloric acid in the conversion of germanium metal or tin metal to element tetrachloride …

Biomimetic Adhesive Thiol-Ene Films For Improved Adhesion, Laken L. Kendrick

Honors Theses

Current dental restoration materials fall short in adhesion and often pull away from the surface of the tooth upon curing. This project seeks to design polymers that can adhere to wet, heterogeneous surfaces as potential materials for dental restoration applications. The goal of this project is to mimic the structure and adhesive properties of natural adhesives containing 3,4-dihydroxyphenyl-L-alanine (DOPA). We will synthesize mono- and di-functional DOPA derivatives with catechol functionality and investigate their adhesion compared to their non-catechol-containing alternative through incorporation into a model thiol-ene photopolymerization. Functional group conversion, real time kinetics, and adhesion data will be used to analyze …

A Lab To Stemulate Undergraduate Students Into Science, Technology, Engineering And Mathematics Majors, Nicole Lynn Speelman

Browse all Theses and Dissertations

The central focus is the development and implementation of a research/lab module for first year chemistry courses. Electrochemical techniques are utilized to study oxidation and reduction reactions of neurotransmitters with a poly(2,2'-Bithiophene) modified electrode. The goal is to excite students about chemistry and encourage them to continue studies in Science, Technology, Engineering, and Mathematics (STEM) during their undergraduate education. The lab module was created for Project REEL (Research Experiences to Enhance Learning) and will be illustrated with results typically obtained by students. The experiment is inquiry-based, which includes challenging questions students have to do collaboration and research to answer, as …

Gas-Phase Formation Of Environmentally Persistent Free Radicals From Thermal Degradation Of Catechol, Hydroquinone, Phenols And Tobacco, Julien Gnonlonfoun Adounkpe

LSU Doctoral Dissertations

Catechol, hydroquinone and Phenol are major constituents of the mainstream tobacco smoke. The toxicity of tobacco has been attributed to the ability of catechol and hydroquinone to undergo endogenous or exogenous redox cycling to form semiquinone type radicals responsible of Reactive Oxygen Species (ROS) formation. ROS such as hydroxyl radicals can cause severe oxidative stress on biological tissues and can provoke severe signaling pathways leading to cardiovascular and pulmonary dysfunctions and carcinogenesis. Given that semiquinone type radicals are organic radicals, characterized by their high instability and reactivity; it is somewhat surprising that they can live long enough mostly when associated …

Copper(Ii) Oxide Mediated Formation And Stabilization Of Combustion Generated Persistent Free Radicals, Hieu Truong

LSU Doctoral Dissertations

Biologically damaging semiquinone-type radicals have been reported in cigarette smoke, their likely origin being hydroquinone (HQ) and catechol (CT) molecular precursors contained by the tobacco. Since other biomass contains HQ and CT-type species, it is likely that combustion of other biomass will also form semiquinone-type radicals. All hydrocarbon fuels will form phenol and substituted phenol that can form substituted phenoxyl radicals. Because each of these radicals has the potential to be environmentally persistent and biologically active, their formation and stabilization from various molecular precursors was studied with the focus on surface-bound radicals formed in association with combustion-generated fly-ash particles. Comprehensive …

A Polarographic Study Of Fe(Ii) And Fe(Iii) Complexes With Catechol, Wen-Tang Shen

Dissertations and Theses

A study of the anodic polarography of catechol in 0.100 F sodium perchlorate is presented. A new wave is observed in alkaline solutions which is different from the simple oxidation wave of catechol to ortho-quinone observed by previous workers. The importance of buffer materials is discussed and a possible explanation of the new wave is suggested.

A study of the polarography behavior of Fe(II) and Fe(III) in the presence of catechol is reported. In the case of reduction of Fe(III) in the presence of catechol, two steps occur at about -1.5 and -1.8 volts (vs. SCE) at pH higher than …

An Investigation Of Arsenic(V)-Catechol Complexes, Ronald P. Haak

Dissertations and Theses

There is not, at this time, a simple method for the simultaneous determination of As (III) and As (V) at trace levels. The development of such as method is needed, as the toxicities of these two species differ so greatly.

As (III) and As (V) are polarographically reducible in the presence of excess catechol, but the wave produced by As (V) is depended on time, pH and catechol concentration as well as As (V) concentration. In order to understand this behavior, determination of formation constants for any complex species present were needed to identify which species is electroactive. The literature …

Reaction Of Aqueous Catechol Solutions With Minerals, Boonthong Poocharoen

Dissertations and Theses

The effectiveness of catechol, an aromatic vic-diol, in dissolving silicate minerals was studied. A synthetic amorphous magnesium trisilicate, Mg₂Si₃O₈∙5H₂O, as well as the minerals olivine, sepiolite, diopside, augite, and enstatite were used to react with catechol in slightly acidic, basic, and neutral solutions. It was found, depending on the solvent used, that 33-52, 8-17, 14-30, 5-11, 3-6, and 0.5-1 % of the minerals dissolved, respectively.

The reaction with Mg₂Si₃0₈·5H₂0 resulted in the formation of crystals of magnesium tris (catecholato) siliconate nonahydrate Mg[Si(Cat)₃]∙9H₂0. Dehydration of the crystals at room temperature resulted in the loss of 6 moles of water to form …