SELECTIVE C-H AND ALKENE FUNCTIONALIZATION VIA ORGANIC PHOTOREDOX CATALYSIS

Photoinduced electron transfer (PET) can be defined as the promotion of an electron transfer reaction through absorption of a photon by a reactive species in solution. Photoredox catalysis has leveraged previous knowledge of PET processes to enable a wide variety of high value chemical transformations. Most early work in the field of photoredox catalysis centered around the use of visible-light absorbing transition metal catalyst systems based on ruthenium or iridium polypyridyl scaffolds, organic redox chromophores offer a more sustainable, accessible, and versatile alternative to these complexes. Organic photoredox catalysts are often less expensive, easier to prepare, and have expanded redox windows relative to many known transition-metal photoredox catalysts, enabling the generation of a wider variety of single electron reduced/oxidized species. This ultimately translates into the development of previously undiscovered modes of reactivity. Herein is described the development and mechanistic study of a several C-H and alkene functionalization reactions facilitated by visible light-absorbing acridinium salts, as well as the discovery and characterization of a neutral organic radical which possess one of the most negative excited state oxidation potentials observed to date. Through single electron oxidation of protected secondary amines, the corresponding neutral alpha-carbamyl radical species may be generated and utilized in a formal carbon-carbon bond forming C-H functionalization reaction. Electron rich arenes are amenable to functionalization via net oxidative or redox neutral pathways using similar catalytic systems. Upon generation of an electrophilic arene cation radical through PET, diazoacetate derivatives undergo nucleophilic addition to these intermediates, affording formal C-H functionalization products containing a new sp3-sp2 carbon-carbon bond. Methods for the anti-Markovnikov functionalization of activated olefins are also accessible via photoredox catalysis. Acridinium salts are shown to serve as competent catalysts in electrophilic hydroazidation reactions of activated olefins in combination with a sterically hindered thiol hydrogen atom transfer catalyst. An investigation of the photophysical behavior of a neutral acridine is presented. A multifaceted spectroscopic, computational, and experimental study suggests excitation of this species leads to the population of several extremely reducing doublet excited states. The in situ generation and excitation of this species enables a variety of catalytic reductive photoredox transformations.  Doctor of Philosoph

Defending the Pittsburgh Waterways Against Catastrophic Disruption

This thesis develops an Operatorâ s Model that mimics the real-world behavior of coal transport in the Port of Pittsburgh and allows for systematic investigation of â what ifâ disruption scenarios. We model the multi-modal flow of coal using a network of nodes and arcs representing river transport, with support from a surrounding system of rail lines and roads. Each mode of shipment has finite capacities with varying costs. Our model routes flows in order to satisfy contracted supplies and demands at minimum transportation cost. We use 2009 coal shipment data provided by the United States Army Corps of Engineers to drive delivery patterns. We focus our attention on the Monongahela River, which carries a significant amount of coal through our system. We employ Defender-Attacker-Defender techniques to assess critical infrastructure in the context of an intelligent adversary, such as a terrorist, who seeks to damage the system so as to maximally increase its operating cost. This allows us to assess the relative importance of critical system components in order to help the United Stated Coast Guard identify where to focus their attention.http://archive.org/details/defendingpittsbu109457296Captain, United States Marine Corp

(4-Hydr­oxy-2-oxidobenzaldehyde thio­semicarbazonato-κ3 O 2,N 1,S)(1,10-phenanthroline-κ2 N,N′)zinc(II) dimethyl sulfoxide disolvate monohydrate

The ZnII atom in the title compound, [Zn(C8H7N3O2S)(C12H8N2)]·2C2H6OS·H2O, is N,N′-chelated by the N-heterocycle and N,O,S-chelated by the deprotonated Schiff base in a distorted square-pyramidal enviroment. Hydrogen bonds link the mononuclear mol­ecule, the water and the dimethyl sulfoxide (DMSO) mol­ecules into a linear chain motif. One DMSO mol­ecule is disordered over two positions in respect of the S atom in an approximate 1:1 ratio

Rapid detection of Ganoderma-infected oil palms by microwave ergosterol extraction with HPLC and TLC

Detection of basal stem rot (BSR) by Ganoderma of oil palms was based on foliar symptoms and production of basidiomata. Enzyme-Linked Immunosorbent Assays-Polyclonal Antibody (ELISA-PAB) and PCR have been proposed as early detection methods for the disease. These techniques are complex, time consuming and have accuracy limitations. An ergosterol method was developed which correlated well with the degree of infection in oil palms, including samples growing in plantations. However, the method was capable of being optimised. This current study was designed to develop a simpler, more rapid and efficient ergosterol method with utility in the field that involved the use of microwave extraction. The optimised procedure involved extracting a small amount of Ganoderma, or Ganoderma-infected oil palm suspended in low volumes of solvent followed by irradiation in a conventional microwave oven at 70 °C and medium high power for 30 s, resulting in simultaneous extraction and saponification. Ergosterol was detected by thin layer chromatography (TLC) and quantified using high performance liquid chromatography with diode array detection. The TLC method was novel and provided a simple, inexpensive method with utility in the field. The new method was particularly effective at extracting high yields of ergosterol from infected oil palm and enables rapid analysis of field samples on site, allowing infected oil palms to be treated or culled very rapidly. Some limitations of the method are discussed herein. The procedures lend themselves to controlling the disease more effectively and allowing more effective use of land currently employed to grow oil palms, thereby reducing pressure to develop new plantations.This project was supported by the Fundamental Research Grant Scheme (FRGS), administered through the Ministry of Higher Education, Malaysia (Grant No: 5524175)

An optimized gas chromatographic determination of priority pollutant phenols

Priority pollutant phenols are determined by gas chromatography on an SE‐30 WCOT column using hydrogen carrier and flame ionization detection with dual internal standards. Linear responses over ranges ca. 12–125 ng per component are achieved and detection limits at or below 1 ng are obtained. Carrier flow and temperature program are optimized to maintain baseline resolution while affording an analysis time of less than 15 minutes