A practical and versatile instrument has been developed both to
optimize the chemistry of bio- and chemiluminescence reactions and to
measure ultra-trace quantities of associated analytes. The instrument
consists of a pneumatic flow injection system linked to a detection cell and a
signal processing and readout system. The disk-like cell...
The stereocontrolled synthesis of the southern lactone 17 of
boromycin and of the northern segments of both boromycin and aplasmomycin
are described. The syntheses begin with enantioselective
epoxidation of 3-buten-2-ol (42) to provide the optically active
2(S),3(R) epoxy alcohol 43. The absolute configuration was confirmed
by preparing 43 from (-)-2,3-dihydroxybutyric...
A synthetic approach toward the two major fragments of cathedulin K-19,
euonyminol (4) and dimethyl cathate (69), was investigated. Synthesis of
dimethyl cathate was accomplished in 3 steps starting from 73. Efforts directed
towards the synthesis of euonyminol, a highly oxygenated dihydroagarofuran
sesquiterpene, was advanced to a stage in which...
Studies toward the total synthesis of a highly potent cytotoxic marine natural product, phorboxazole A, were conducted and resulted in a route to an advanced intermediate, C4-C32, for this purpose. A key feature of our approach is the stereoselective synthesis of two cis-2,6-disubstituted tetrahydropyrans present in the macrolide portion of...
Two approaches to the tricyclic core of the furanoeremophilane sesquiterpenoids are described. The first approach entails a projected Diels-Alder/retro Diels-Alder reaction of an acetylenic oxazole 64. Construction of the pivotal aldehyde 67 commenced from ketone 68. The acetyenic moiety was then introduced via a Felkin-Ahn addition of lithiopropyne to aldehyde...
An on-line trace enrichment (TE) system, based on high pressure
liquid chromatogroaphy (HPLC) and flame atomic absorption (AA), has
been developed for trace metal analysis. The sample is pumped through
a column filled with a cation exchange resin which traps metal ions.
The ions are subsequently stripped from the column...
The total synthesis of a highly potent cytotoxic marine natural product, phorboxazole A, is described. Both a palladium(II)-mediated and a palladium(II)-catalyzed intramolecular alkoxycarbonylation were used as key steps for the preparation of the two cis-2,6-disubstituted tetrahydropyran rings (C22-C26 and C11-C15) of phorboxazole A.
The synthesis used a convergent approach involving...
PART I. Asymmetric syntheses of both natural (+)- and nonnatural (-)-byssochlamic acid via a [2+2] photoaddition-cycloreversion strategy are described. X-ray crystallographic analysis of the cyclohexylamine salt 99 showed that the structure of the monomethyl ester 100 from esterase hydrolysis of 44 was originally misassigned as 56. The enantiomeric relationship of...
PART I. The preparation of (-)-ibogamine (1) in fourteen steps from benzoquinone and in 10% overall yield is a powerful illustration of the value of the asymmetric Diels-Alder reaction as a starting point in a multistep synthesis. All four cycloadducts, 70, 77, 84 and 96, obtained with the (S)-BINOL-TiCl₂ complex...
A new experimental apparatus was built at Oregon State University to perform high resolution stimulated Raman spectroscopy in a pulsed molecular jet at state densities of the order of 10¹¹ cm⁻³. The technique uses a stimulated Raman step to first populate a vibrational/rotational level and then a resonantly enhanced multiphoton...
The high resolution stimulated Raman spectrometer at OSU was
modified to improve its sensitivity and to extend its range of
applications to low Raman shifts and to the spectroscopy of solids and
liquids. As part of the characterization of the spectrometer, optical
Stark effects on rotational and vibrational transitions of...
The use of semi-volatile organic compounds (SOCs) as molecular markers to identify the contributions of regional and long-range atmospheric transport, as well as current and historic sources, and contaminant deposition in remote ecosystems of the Western U.S. was investigated. Trans-Pacific air masses influenced by Siberian biomass burning events had elevated...
Chlorinated aliphatic hydrocarbons (CAHs) such as vinyl chloride (VC) and 1,-2 dichioroethane (DCA), are wide-spread groundwater pollutants found at many contaminated field sites around the world. Quantitative tools are needed to determine the in situ rates of VC and DCA transformation to ethene in contaminated groundwater. The objective of this...
The electrochemistry of the lithium-potassium-sodium
carbonate-borate melt was explored by voltammetry and chrono-amperometry. In support of this, a controlled-potential polarograph
and associated hardware was constructed.
Several different types
of reference electrodes were tried before choosing a porcelain membrane electrode containing a silver wire immersed in a silver sulfate
melt.
The...
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants formed from the incomplete combustion of organic material. These contaminants are of concern because of their widespread presence in the environment and toxic properties. In addition, PAHs encompass a class of diverse compounds with varying physicochemical properties and exist in the environment as...
3-Methyl-2,4-dioxabicyclo [3.3.1] nonane and 7-hydroxy-3-methyl-2, 4-dioxabicyclo [3.3.1] nonane were synthesized by the
method of Croxall, Glavis and Neher, although in low yields.
The structure of both compounds was proven by analytical
methods and analysis of their spectral properties.
Tentative configuration of C-3 in both compounds was
assigned on the assumption...
In this thesis, I present a new method we developed to study low frequency (< 700 cm⁻¹) vibrational dynamics: Time-resolved third-harmonic generation (TRTHG) spectroscopy. Among a variety of vibrational spectroscopy techniques, TRTHG differentiates itself with robustness, versatility, and simplicity. In TRTHG experiment, that involves only two ultrashort laser pulses, the...
Direct current conductivity measurements on KC1:O[superscript]= crystals
were used to determine an enthalpy of 0.42 ev for the dissociation for
anion-vacancy-oxide ion complex.
The entropy of dissociation was
found to be approximately -4x 10⁻⁴ev deg⁻¹. The intrinsic "activation" energy was found to be 1.91 ev as compared to 1.95 ev,...
Heats of immersion were obtained for four different organophilic
clay complexes in a series of normal alcohol-heptane mixtures
with alcohols of increasing chain length. The immersion calorimeter
employed was the Dewar type with a sensitivity of approximately
5 x 10⁻⁵°C.
Gel volumes were determined for two of the clay complexes...
While fluorochemicals have been detected all over the world and in wastewater
treatment plants, the effect of wastewater effluent on the receiving waters has not been
evaluated. In the first study, the mass flow of fluorochemicals emanating from
wastewater treatment plants along the Glatt River in Switzerland was evaluated. The...
Capillary electrophoresis as a technique has many applications in a broad range of fields including forensics, environmental analysis, and biological analysis and as a separation method for samples such as oligonucleotides, peptides, proteins, and pharmaceuticals. The research conducted herein is for the antibiotic pharmaceutical ciprofloxacin HCl and three impurities. Sample...
The photochemical reaction between O⁻ ions and F centers
was investigated. The activation energy was determined by the
Arrhenius law to be 0.10 + 0.04 eV for temperature below 180°K.
The diffusion of alpha centers towards the oxide ion was eliminated
as the rate limiting step and the low trapping...
A continuous amperometric monitor for aqueous sulfite solutions
has been developed employing the electro-oxidation of sulfur (IV)
in 0. 1 M sulfuric acid at a glassy carbon test electrode. The monitor
employs a hydrodynamic flow cell, in which the solution stream
enters the cell through an orifice impinging on the...
The work presented here is focused on applying basic principles of solid-state chemistry to the study and development of new wide band-gap semiconductors and insulators for photovoltaic and electronic-device applications. Analysis of crystal structure, band structure, optical band gap, morphology and transport properties provides fundamental insight into materials performance as...
Reaction of 4, 6-dimethoxy-5-nitropyrimidine [I], with refluxing
pyridine, was discovered to yield the methylpyridinium salt of
1, 6-dihydr -4-hydroxy-1-methyl-5-nitro-6-oxopyrimidine [III]. Possible
use of I as a general N-methylating agent was explored. No
appreciable reaction occurred between I and refluxing excess n-butyl
alcohol. Similar reaction involving quinoline failed to yield an...
SOCs volatility and persistence properties cause many SOCs to become ubiquitous in the environment as well as accumulate in areas with lower temperatures such as polar or orographic regions. Many anthropogenic SOCs pose a serious risk to human and ecosystem health because of their persistent, bioaccumulative, and toxic properties in...
The transport and deposition of airborne contaminants, including semivolatile
organic compounds (SOCs), to high elevation ecosystems is
recognized as a potential threat to these ecosystems. The objectives of
this research were to develop an analytical method to measure a wide
range of SOCs in high elevation lake sediment and to...
Ultraviolet spectroscopy and dispersive solubility parameters
correlated to the ratios of retention times have proven valuable in
classification of gas chromatography stationary phases by the donor-acceptor
properties. Iodine was directly dissolved into stationary
phases and the absorption frequency shift of complexes was correlated
with the carbon tetrachloride/chloroform retention ratio on...
The incorporation of europium and dysprosium in potassium
chloride crystals was investigated. The crystals were prepared by
the Kyropoulos method from melts containing the rare-earth chlorides.
The concentration of these rare-earth ions in the crystals was determined
by neutron-activation analysis. The distribution coefficient of
europium and dysprosium between the molten...
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants and are mostly products of the incomplete combustion of organic material. PAHs are often found in environmental samples as a complex mixture of isomers. In addition, the same sources that produce complex PAH mixtures also produce other poorly characterized mixtures of organic compounds,...
Trichloroethene (TCE) is the most frequently detected organic contaminant in groundwater, is classified as a probable human carcinogen, and exhibits toxicological effects on the human endocrine, immune, developmental, and reproductive systems. While significant research efforts have been devoted to the development of strategies for remediating TCE-contaminated groundwater, their advancement is...
Halogenated Polycyclic Aromatic Hydrocarbons (X-PAHs) are ubiquitous contaminants that are thought to be generated by processes such as chemical industries and incomplete combustion, including waste incineration and electronic waste (e-waste) burning. X-PAHs are a concern for environmental and human health because they are toxic, mutagenic, and are expected to be...
Preparation of a cytochrome c-cytochrome oxidase complex
was achieved, using crystalline beef cytochrome c and purified
cytochrome oxidase from beef heart muscle, or from the
Keilin-Hartree preparation. Succinate oxidase was reconstituted
with the complex.
A mixture of cytochrome oxidase, solubilized with nonionic
detergent, and excess cytochrome c was exposed to...