Physical Sciences and Mathematics Commons^™

Studies Directed Toward The Synthesis Of Germacranolides Via [2+2] Cycloaddition Followed By Ring Expansion/Elimination Of Β-Lactones, Bryan E. Yates

Masters Theses

Exposure of α-trimethylsilyl β-lactones to magnesium bromide or boron trifluoride etherate in diethyl ether solvent resulted in the smooth generation of β,γ-unsaturated acid derivatives in good yield and isomeric purity. It is believed that this reaction occurs via the formation of a stable tertiary carbocation at the γ-carbon resulting from cleavage of the carbon-oxygen sigma bond due to the complexation of the Lewis acid with the ring oxygen atom. Rapid loss of an adjacent electrofuge then furnishes the unsaturated acids. The β-lactone precursors were prepared by a [2+2] cycloaddition of an aldehyde and an alkyl trimethylsilyl ketene. This method was …

The Synthesis And Characterization Of Ruii(Bpy){(Bpyrm)Ruii(Nh3)4}2](Pf6)6 And [Ruii(Bpy)2(Bpyrm)Ruii(Nh3)4](Pf6)4, Rick Anthony Pavinato

Masters Theses

This thesis describes the synthesis of a trimetallic Ru^II complex [Ru^II(bpy){(bpyrm)Ru^II(NH₃)₄}₂](PF₆)₆ and its bimetallic analog [Ru^II(bpy)₂(bpyrm)Ru^II(NH₃)₄](PF₆)₄. The trimetallic species was designed to be the first in a series of complexes where the reduction potential of the "bridging" complex could be varied (relative to the "terminal" sites) through systematic variation in the metal (M) and/or ligand (LL) … Generation of the [Ru^II-M^II-Ru^III] "mixed-valence" complex would then allow …

Kinetic And Chemical Modification Studies On Malate Dehydrogenase From E. Coli, Fang Jenny Zhao

Masters Theses

Malate dehydrogenase (MDH) is the enzyme which catalyzes the conversion of malate to oxaloacetate in the TCA cycle. The object of this research was to discipher the mechanism of the reaction and the function of the enzyme. MDH from E. Coli was purified and analyzed by chemical modification studies using diethylpyrocarbonate. Results indicate the existence of a histidine residue at the active site necessary for catalysis. From kinetic studies, a group required for catalysis with a pK_a of 8.5 was observed, which we believe to be a histidine residue. These studies indicate that MDH from E. Coli has a …

Effect Of Reservoir Function On Water Quality And Phytoplankton In Lake Taylorville, Christian County, Illinois, Scott Warren Phipps

Masters Theses

As is true for most reservoirs in agricultural areas, Lake Taylorville is currently impacted by excess sedimentation. A system of floodplain wetlands, holding ponds, and sediment basins is being constructed on the tributaries to the reservoir in effort to reduce sediment and nutrient loads. A comprehensive twelve-month assessment of water quality has been conducted to provide a baseline for evaluating the success of this restoration project and to allow predictions regarding future management strategies.

In reservoirs, a continuum of longitudinal gradients result in the establishment of three distinct zones possessing unique physical, chemical and biological properties. The function of these …

Macroporous Polymer Synthesis And Characterization: The Role Of Molecular Recognition In The Regioselectivity Of Sucrose Reactions, Gilbert Joshua Matare

Masters Theses

Molecular recognition has recently emerged as a unique technique for making synthetic polymers with selective binding cavities which can stereoselectively and regioselectively bind to a template molecule in a fashion similar to natural enzymes and antibodies. Its industrial applications in chemistry and biomedicine have been recently exploited. Typical examples include the resolution of amino acids, enantio-separation of racemates and bioactive molecules, selective binding of metal ions and in HPLC investigations. Our research is focused on applying molecular recognition studies to improve the regioselectivity of sucrose reactions.

Sucrose is an abundant industrial raw material of immense industrial importance however, its full …

Carbonyl Homologation Via Α-Trimethylsilyl Β-Lactone Rearrangement: A Nonbasic Wittig Alternative, Yong Zhang

Masters Theses

Our research group has been interested in β-lactones as useful synthetic intermediates. Transformations of β-lactones, generally ring expansion/opening processes initiated by Lewis acids via ionization/cation-rearrangement or elimination mechanisms, provide efficient protocols for the syntheses of biologically important butyrolactones, β,γ-unsaturated carboxylic acids, or butenolides.

α-Trimethylsilyl β-lactones, synthesized via the BF₃- catalyzed [2+2] cycloaddition of trimethylsilylketene to carbonyl compounds, spontaneously undergo ionization and trimethylsilyl group migration to form α,β-unsaturated trimethylsilyl esters. The trimethylsilyl moiety facilitates the ionization process because of its β-cation stabilizing ability. The two-carbon homologated α,β-unsaturated acids are formed in yields from moderate to high (41-99%) upon aqueous …

Studies Of Silica As A Polymer Support For Regioselective Reactions On Sucrose, Lei Cheng

Masters Theses

Sucrose is a material that has potential for replacing oil as an industrial feedstock, at least in some instances. A major difficulty in utilizing sucrose is the lack of regioselectivity in its reactions due to the many reactive sites on the sucrose molecule.

This research is part of an attempt to study the technique of molecular recognition in an effort to increase reaction regioselectivity. Molecular recognition by template imprinting should be a way to create a material that would "recognize" and bind to sucrose in such a way as to block certain of the hydroxyl groups on the sucrose. The …