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A Dissertation submitted in fulfillment of the requirements for the degree Master of Science In the Faculty of Sciences at the University of the Witwatersrand, Johannesburg Johannesburg, January 2015 / Three methods, for the analyses of low levels of moisture in gas samples, were developed and optimized. The analytical techniques included Fourier Transform Infrared Spectroscopy (FTIR) and Pulsed Discharge Helium Ionization/Gas Chromatography (PDHID/GC). The methods included the direct analyses of moisture in gas samples using FTIR as well as the analysis of acetylene (C2H2) by FTIR and GC/PDHID. For the latter methods, the purpose was to convert the moisture in a gas sample to C2H2 by hydrolization of the calcium carbide (CaC2) with moisture to C2H2 and then analyze the resulting C2H2 content by FTIR or GC/PDHID. The C2H2 result was then converted back to moisture to obtain the moisture content of the sample. The FTIR moisture method developed provided eleven different wavenumbers for quantitation providing a wide analytical scope, specifically in complex gas matrices, where there is often peak overlap between matrix and moisture. A heated eight meter glass long path gas cell and a mercury cadmium telluride (MCT) detector were utilized. The FTIR method required much greater volumes of sample than the GC method but allowed for direct analysis of moisture without prior conversion to acetylene. Moisture permeation standards were used for calibration and the LOD’s ranged from 0.5 to 1 ppm with quantification possible from 0.5 to 10ppm. For the FTIR C2H2 method various concentration ranges were established from 50 up to 2000 ppm. Three wavenumbers were evaluated for C2H2 and methane was introduced as an internal standard. The use of methane as an internal standard provided better r2 values on the calibration data than for the tests run without internal standard. A gas chromatographic (GC), pulsed discharge helium ionization detector (PDHID) method for the determination of moisture content in small quantities of gases, based on the conversion of the moisture to acetylene (C2H2) prior to analysis, was developed. The method developed on the GC/PDHID for C2H2, provided a quantitation range from 0.6 to 7.7 ppm. Conversion of the moisture to acetylene was achieved by hydrolysing an excess of calcium carbide (CaC2) in a closed reaction vessel with a measured volume of a sample containing a known quantity of moisture. The gaseous reaction mixture was transferred, using helium (He) carrier gas, to a GC/PDHID, set up with “sample injection and heart cut to detector” to prevent matrix disturbances on the PDHID, for analysis. The acetylene concentration values thus obtained were converted back to moisture values and percentage recoveries calculated. A similar conversion process was applied on FTIR. The conversion of moisture to C2H2 using CaC2 was tested and proven to be viable. Quantification was not possible as the available sample holder could not be adequately sealed to prevent air ingress. This led to higher C2H2 values than expected. This process can be optimized by the design and production of a sealed sample holder.

The keytones are representative of one of the large groups of compounds of Organic Chemistry. Phenyl-methyl-ketone is the simplest representative of the mixed aliphatic-aromatic ketones. It is a member of a group of compounds which are soporific and hypnotic and are used in medicine as sleep producers and sedatives. It is found to a small extent in coal tar. It has basic properties and is extracted from the heavy oil of coal tar with sulfuric acid. The purpose of this research is to synthesize one of the compounds which is not present in the compilation of the natural lists and to investigate its properties. The compound that is the focus of this research is acetyl acetophenone. It is next to phenyl-methyl-ketone in the group of mixed aliphatic-aromatic ketones. The relation between these two compounds can best be shown by their structural formulae: PHENYL-METHYL-KETONE [see PDF file for formula] [see PDF file for formula] ACETHYL ACETOPHEMONE

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The thermally induced reaction of halogenated ethylenes on the α-Cr₂O₃ (101̅2) single crystal surface results in the formation of gas phase hydrocarbons including acetylene, ethylene, butadiene, and dihydrogen, and deposition of surface chlorine adatoms. No surface carbon or combustion products are observed in any reactions indicating no thermally induced C-C bond cleavage occurs and surface lattice oxygen is not incorporated into surface intermediates. Thermal desorption spectroscopy indicates that in all halogenated ethylene reactions acetylene is the major product, regardless of the reaction scheme. The surface reactions of halogenated ethylenes are proposed to proceed through C-X (X=halogen) bond cleavage to form surface halogen adatoms and surface C2 hydrocarbon fragments. Halogen adatom deposition affects reaction barriers to hydrocarbon formation, and eventually shuts down surface chemistry. Photoemission and near edge x-ray absorption fine structure spectra show that all studied reactants undergo some C-X bond cleavage upon low temperature adsorption forming adsorbed C2 fragments and halogen adatoms. Photoemission for each reaction system shows at least two C1s features (283.0-286.0 eV) and two Cl2p features (2p_3/2=198.0-201.0 eV) with higher binding energy features associated with molecularly intact halogenated ethylenes and lower binding energy features associated with dissociated surface species. Near edge x-ray absorption fine structure spectra taken, corresponding to photoemission spectra, indicate the occurrence of C1s→π∗ transitions, indicating intact π-systems are present. Heating the surface results in a reduction in intensity of higher energy photoemission and near edge x-ray absorption fine structure indicative of a decrease in surface C-X bonds. / Ph. D.

The mechanism of catalytic hydroboration was studied through the use of iridium and rhodium model complexes. Oxidative addition of the B-H bond in (1,2-phenylenedioxy) borane (catecholborane) to (Me₃P)₃Ir(Cl)(H) (BO₂C₆H₄ (<B>II</B>) produces <i>mer</i>-(Me₃P}₃Ir(Cl)(H)(B0₂C₆H₄) (<B>II</B>), which was characterized by ¹H NMR spectroscopy and single crystal X-ray diffraction. Compound <B>II</B> reacted with alkynes to form vinyliridium complexes and will catalyze the hydroboration of alkynes with (1,2- phenylenedioxy)borane. The reaction of <B>II</B> with acetylenes was inhibited by the presence of free Lewis bases indicating that the reaction proceeds by a dissociative mechanism. Exchange of the chloride ligand in <B>II</B> occurred with other Lewis bases, indicating that chloride dissociation was responsible for opening up the vacant coordination site on the complex and thus providing for acetylene coordination. When the chloride ligand on <B>II</B> was replaced with other Lewis bases, the reactivity towards trimethylsiliylacetylene was qualitatively determined to be inversely proportional to the strength of the new ligand. The above experiments indicated that the mechanism of catalytic hydroboration of acetylenes with catecholborane involves: oxidative addition of the B-H bond to the iridium center, followed by chloride dissociation and acetylene coordination, migratory-insertion into the Ir-H bond to form the metallo-vinyl complex, and finally reductive elimination to produce trans-alkylvinylborole esters. The stable metallo-vinyl complex, <b>IX</b>, produced in the reaction of <b>II</b> with dimethyl acetylene dicarboxylate produced twO isomers in solution, one of which showed fluxional behavior. Single crystal X-ray diffraction elucidated a single solid state structure, but the structures of the isomers in solution and the fluxional properties observed have not yet been explained. The rhodium complex was synthesized by oxidative addition of the B-H bond in (1,2- phenylenedioxy) borane to (Me₃P)₃RhCl producing <i>mer</i>-(Me₃Rh(CI)(H)(BO₂C₆H-₄) (<b>XXIV</b>), which was characterized by ¹H NMR spectroscopy. This complex reacted with acetylenes, but more slowly than the iridium complex, <b>II</b>. The resulting vinyl products were also different than those produced in the iridium case. Phosphine dissociation in <b>XXIV</b> was observed, indicating the possibility of a different mechanism than proposed for the iridium complex. / Ph. D.

Advances in technology have now made it possible to analyze cardiac output (Q) with only a single-breath, making measurements during exercise quicker and less invasive for the subject. Certain non-invasive techniques allow for measurement of the disappearance of a soluble inert gas as it diffuses across the blood-gas barrier in the lungs. The rate of disappearance of the gas is directly proportional to the flow of blood past the lungs and subsequently provides an estimate of pulmonary capillary blood flow (Qc), or Q. The SensorMedics® Corporation (Yorba Linda, CA) has developed a single-breath acetylene (C₂H₂) technique (SensorMedics Vmax 229TM), which includes a simple device to linearize expiratory flow rate by increasing the time by which the sensors can measure the disappearance of the marker gas and improve quantification. The purpose of this investigation was to determine the reproducibility of the C₂H₂ single-breath technique during ramping exercise testing with the addition of a starling resistor in 11 apparently healthy, sedentary volunteers (7 male and 4 female). Subjects performed three maximal ramping exercise test sessions over a 6-week period and Qc was measured at rest and at three time points during the exercise test. The C₂H₂ single-breath Qc measurement technique was shown to be repeatable when systematically related to VO₂ (Qc/VO₂ relation highly correlated r² = 0.72-.74), but slightly lower than previously reported. Means and 95% confidence intervals revealed the precision of the technique over repeated testing days. This method was able to capture Qc measurements at intensities greater than 75% VO₂pk in all subjects with the use of the Starling resistor. Bland-Altman plots reveal Qc measures to be about 50% more variable than highly reproducible measures such as VO₂ and HR. Intraclass reliability coefficients (r) found through repeated measures ANOVA were found to perform low (rx,x= -0.11-0.31) from rest throughout all intensities of exercise. This device is limited in the ability of the sensors to accurately analyze Qc with subjects who are unfamiliar and have difficulty with the single-breath maneuver. Such instances make it difficult for objective, accurate determinations to be made by the clinician. The C₂H₂ single-breath method was found to capture Qc at higher intensities and a high level of precision with the addition of the starling resistor. However, more evidence needs to be analyzed before use of this device can be put into clinical practice. / Master of Science

Master of Science / Department of Physics / Kristan L. Corwin / We investigate the nonlinear spectroscopy of acetylene in the near infrared region inside a photonic band gap fiber. The near infrared region of the optical spectrum is an area of intensive research due to its relevance to telecommunication and optical metrology. Acetylene provides a large number of reference transitions coincident with the international telecommunication band. Acetylene contains about 50 strong lines between 1510 nm and 1540 nm in the ν1+ν3 ro-vibrational combination band. We have observed the Doppler-free saturated spectrum of several of these lines. The light from a tunable diode laser at ~1531 nm, resonant with the P(11) transition, is amplified by an erbium doped fiber amplifier and split into a strong pump beam and weak probe beam which counter-propagate inside the gas-filled fiber. The measured Doppler linewidth of the P(11) line at room temperature is about 467 MHz wide. The sub-Doppler profile over a pressure range of 200-1600 mT appears as a narrow absorption feature about 20-40 MHz wide, even at the low pump power of ~10 mW. It is found that for a fiber with an 80 cm length, 20 core size, pumped with 29 mw, the optimum pressure is ~530mT. But the optimum pressure condition will further decrease when the fiber length increases.