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Browsing by Author "Kurek, Martin"
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Item The Effects of Surfactants on Colloidal, Nanoparticulate, and Dissolved Sulfur(Office of the Vice Chancellor for Research, 2016-04-08) Kurek, Martin; Druschel, Greg; Gilhooly, William P., IIIElemental sulfur is generally insoluble in water unless in the presence of a surfactant. This phenomenon was investigated by Steudel and Holdt in 1988 by filtering mixtures of sulfur, water, and surfactants through a 0.45 micron filter; however, since then sulfur nanoparticles smaller than 0.45 microns have been detected. The smaller than expected particle size suggests that the distribution of elemental sulfur in water with surfactants may be partitioned into colloidal, nanoparticulate, and truly dissolved components. Experiments have been conducted measuring the sulfur solubility in water with several chemical surfactants and varying filter sizes smaller than 0.45 microns. These experiments were conducted under equilibrium conditions with the solubility being measured using HPLC and square wave voltammetry. Kinetic studies detailing the solubility of sulfur with the surfactants over time have also been investigated. Data regarding the size and occurrence of sulfur nanoparticles present in water and the surfactants has been collected as well to give a complete description of the system under examination. Sulfur isotope fractionation of the dissolved sulfur species is also an interesting component of the system that is currently being investigated using stable isotope ratio mass spectrometry of 34S.Item Palladium-Catalyzed Site-Selective Fluorination of Unactivated C(sp3)−H Bonds(ACS, 2015-07) Miao, Jinmin; Yang, Ke; Kurek, Martin; Ge, Haibo; Department of Chemistry & Chemical Biology, School of ScienceThe transition-metal-catalyzed direct C–H bond fluorination is an attractive synthetic tool toward the preparation of organofluorines. While many methods exist for the direct sp3 C–H functionalization, site-selective fluorination of unactivated sp3 carbons remains a challenge. Direct, highly site-selective and diastereoselective fluorination of aliphatic amides via a palladium-catalyzed bidentate ligand-directed C–H bond functionalization process on unactivated sp3 carbons is reported. With this approach, a wide variety of β-fluorinated amino acid derivatives and aliphatic amides, important motifs in medicinal and agricultural chemistry, were prepared with palladium acetate as the catalyst and Selectfluor as the fluorine source.