The reaction of nitric oxide (NO) with several organic and model biological compounds was studied to determine the ultimate fate of NO in a biological milieu, and to devise novel methods of trapping and analysing NO. A series of potential spin traps including anthracene, o-quinone and 2- acetylcyclohexanone was investigated by bubbling NO through a solution of the above compounds. The resulting mixture was analysed by EPR spectroscopy and GC-MS. The EPR spectra obtained showed no radicals were produced and GC-MS analysis revealed only unreacted starting material. Dienes were investigated because of their willingness to react with radical species. Trans-1,4-diphenyl-1,3-butadiene did not form a nitroxide when reacted with NO, but in the presence of molecular oxygen, 2,5-dimethyl-2,4-hexadiene gave a mixture of a di-t-alkyl nitroxide and a t-s-dialkyl nitroxide. Traps related to nitromethane anion were investigated in basic solution to generate the aci form, but the only compound to give a spin adduct was nitroethane, and this did not give the expected EPR spectrum. 2-Diazocycloheptanone was synthesised from cycloheptanone and reacted with NO. This reaction produced E and Z iminoxyl radicals and a carbonyl nitroxide. When the solvent was changed from t-butyl benzene to water, no reaction was observed. A known NO donor, S-nitroso-N-acetyl penicillamine (SNAP), was mixed with the spin trap and photolysed, but this did not produce a spin adduct. A second diazo compound, 5-diazouracil, was investigated, and this produced a radical species with complex but weak EPR spectra. Nitric oxide was reacted with stable free radicals to provide a quantitative spectrophotometric test for NO. Tetraphenylhydrazine was prepared which is in equilibrium with the diphenylaminyl radical in solution. The diphenylaminyl radical trapped NO and was detected by UV/vis spectroscopy, reaching a λ[sub]max after about one hour. When the solvent was changed from t-butyl benzene to acetonitrile, the reaction took place much more rapidly. From these results it appeared that NO could be detected at concentrations beteween 10 −4 and 10−7 M. Nitric oxide did not react with the parent compound, diphenylamine. When mixed with NO2, diphenylamine formed nitro addition products. Another stable radical, galvinoxyl, was investigated. This did not rapidly scavenge NO to give an identifiable adduct. Nitric oxide was reacted with several alkenes with electron-releasing groups and alkenes with electron-withdrawing groups. The reaction between n-butylvinyl ether and NO was investigated at room temperature. Many oxidation products were identified from the mass spectra obtained. Oxidation products were also identified from the reaction between NO and 1-cyclohexenyIoxytrimethylsilane. Analysis by EPR spectroscopy revealed the presence of two radicals, likely to be dialkyl nitroxides. No products were observed in the reaction of NO and methyl linoleate. EPR spectroscopy of a solution containing mesityl oxide and NO revealed the presence of three radicals, E and Z conformers of the iminoxyl radical, and a carbonyl nitroxide. 1-Acetylcyclohexene reacted with NO to give a di-t-alkyl nitroxide. Synthesis and subsequent photolysis of 1-acetylcyclohexenyl oxime confirmed this result. Another acceptor compound studied was tetracyanoethene; this did not react with NO. Cyclopropylacetyl peroxide was investigated, as decomposition gives the cyclopropyl methyl radical. Analysis of the resulting solution showed that bicyclohexyl had been formed, but there were no traces of any nitrogen-containing products. Nitric oxide did not react with either glutathione or dibenzyl disulphide, but NO2 reacted with L-tryptophan forming a radical adduct. Analysis by EPR spectroscopy yielded a strong three-line signal, characteristic of a nitroxide. The abstraction of hydrogen from, and the rearrangement of selected silylamines was investigated. The amines were photolysed in the presence of di-t-butyl peroxide in the cavity of the EPR spectrometer at temperatures ranging from 160K to 250K. The spectra obtained showed the unrearranged and rearranged radicals. No nitrogen-centred radicals were observed by EPR.

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Bibliography: pages 163-169. / The objective of this work was to produce γ-linolenic acid (γLA) using a fungus in submerged fermentation. Selection work was aimed at identifying a fungal strain capable of yielding a high level of γLA in an industrial fermentation. Thirty-nine fungal strains were screened under shake flask conditions. The major criteria used in evaluating these strains were, the yield of γLA per unit volume (g/l) and γLA as a percentage of fatty acids, which is important in the downstream processing of γLA . Other parameters of industrial importance such as strain handling and the fatty acid profile were also considered. Eleven fungi in the order Phycomycetes were identified after initial screening. From these fungi, a strain of Choanephora cucurbitarum was found to give superior γLA yields. c. cucurbitarum produced γLA yields of 331mg/l and 674mg/l in shake flask and laboratory fermenters respectively. This strain had other industrially beneficial qualities such as good sporulation, a good biomass of 22, 5g/l and a relatively high yield of γLA of 2,99g/100g dry matter. Subsequently a Zygorhynchus heterogamus strain was found to give similar yields of γLA to c. cucurbitarum. z. heterogamus also had a high γLA : linoleic acid ratio which aids the purification of γLA . This is the first known report of a high level of γLA in the genus Zygorhynchus. The industrial development of γLA production by Zygorhynchus is not reported.

The purpose of the investigation was to determine the influence of certain factors on the velocity of saponification of fats and oils by potassium hydroxide. The idea of measuring the velocity of a reaction was first suggested by K. F. Wenzel in 1777. Wenzel defined the velocity of a reaction as the ratio, ( x/d±\ of the amount of substance changed to the time in which it is changed. This definition is still accepted. The factors influencing the velocity of a reaction are, in general, the concentration of the reacting substances, the temperature, the pressure, the solvent, catalytic agents, and the homogenity or heterogenity of the system. Of these, the factors that need to be considered in this work are: (a) Concentration of reacting substances (b) Temperature (c) Solvent (d) Catalytic agents. The influence of concentration on the velocity of reaction is best stated by the law of mass action; the velocity

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 18, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. Jeffre D. Firman. Includes bibliographical references.

Color formation in oils during frying is one of the most noticeable degradation reactions that occur in the frying oil. Degradation reactions cause formation of products that positively and negatively impact the nutritional and sensory qualities of both the food being fried and the frying oil. The origins of these pigment forming reactions in the oil and the factors affecting these reactions are not well understood. Assessments of the mechanisms, the components involved and external conditions affecting oil darkening were conducted. The effect of basic food ingredients, commercially sold and laboratory formulated breading and battering, preformed lipid hydroperoxides and phospholipids on color formation and oil degradation of the frying oil were investigated. Protein products, specifically whey protein, caused both the fastest darkening and thermo-oxidative deterioration of the frying oil. This breakdown was aided further through the addition of minor food materials such as glucose and amino acids as well as lipid hydroperoxides in concentrations greater than 5 % of the frying oil. Nonenzymatic browning is the main reaction causing color formation in the frying oil and utilizes carbonyls from the food product such as starches, sugars and lipid oxidation products as starting materials alongside amino groups from proteins and amino acids. Breading ingredients contributed to oil color formation due to particles from the food crust breaking off into the frying oil to further accelerate browning reactions. Increasing the temperature of the frying oil provided additional stimulus for color forming and thermo-oxidative reactions to progress at a faster rate. / xv, 184 leaves : ill. ; 29 cm

Thesis (M. Sc.)--University of Hong Kong, 1998. / Includes bibliographical references (leaves 40-42).

Interesterification which can be considered as the removal of fatty acids at random from glyceride molecules, the shuffling of these acids and their replacement of the glyceride molecules, has been investigated for palm oil, palm oil fractions and palm oil mixed with other vegetable oils. The reaction has been effected at 90 C in the presence o£ sodium methoxide as a catalyst. Pancreatic lipolysis has been ernployed to check the completeness of the reaction. On complete randomisation, the fatty acid composition of the 2-position is the same as that of the whole fat either before or after interestelification. The changes in the glyceride composition resulting from interesterification have been exarnined by various standard techniques. Silver ion thin layer chromatography which separates glycerides according to their degree of unsaturation has been used extensively. Using luethyl heptadecanoate as an internal standard various component glycerides have been quantified. GLG of glycerides has also been used to study the changes in glyceride composition of fats containing a wide range of fatty acid composition. The application of thin layer chromatography, using methyl heptadecanoate as an interncll standard, has also been extended to deterrnine the esters formed during interesterification when sodium methoxide is used as a catalyst. The changes in physical properties which result from interesterification have been determined by NMR (solids fat content) and DSC (thermal behaviour). Attempts to prepare a mixture of fats and oils containing palm oil and / or palm oil fractions which simulates vanaspati have been made. Many mixtures have been subjected to interesterification and the physical properties of the products have been investigated using NMR for all the mixtures and DSC of selected mixtures. The SFC curve of each mixture has been compared with that of vana spati. useful mixtures are recognised. Some potentially Stereospecific glyceride analysis of various types of palm oils has also been carried out using Brockerhoff's method. This involves partial deacylation of the triacylglycerols, isolation of the a,B-diacylglycerols, conversion of these diacylglycerols to phospholipid derivatives and finally stereospecific hydrolysis by Phospholipase A 2 from snake venom, The possible component glycerides have then been computed as suming a i-random, z- random, 3-random distribution of the fatty acids found in each of these positions. The results have been discussed in tenus of double bond number and of carbon number: The latter has been compared with results obtained by gas chromatography of the whole oil.

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Graduation date: 1960