Thesis (Ph. D.)--University of Nebraska. / Bibliography: p. 38-40.

Thesis (Ph. D.)--University of Nebraska, 1937. / Bibliography: p. 27-28.

Thesis (Ph.D.)-- University of Wisconsin--Madison, 2008. / Includes bibliographical references.

Fatty acids containing a furan ring system were recently discovered by North American Scientists in the liver and testicular lipids of northern pike. We developed an analytical procedure based on urea crystallization and argentation thin layer chromatography for the isolation of small quantities of these novel acids. Using this method a large number of fish lipids taken from both freshwater and marine habitats wore examined. Our results show the wide occurrence of furanoid acids in fish at a low level (up to 5%), These unusual acids tend to concentrate in the cholesterol esters and appear to be absent from the phospholipids. Contrary to claims by the North American researchers we do not find a significant relation between the occurrence of these acids and the sex of the species or on whether the lipid is derived from a freshwater or marine source. We consider rather that the nutritional status of the animal is more significant. Cod liver oil usually contains furanoid acids at about 1% level but in two starved cod the proportion of these acids rose dramatically to 34 and 48% respectively. We also examined four commercial fish meals but furanoid acids were not present in any of them. Furanoid fatty acids were found to accumulate in the adipose tissue of rats given cod liver oil. No furanoid acids were demonstrable in comparable samples from rats given synthetic 10,13-furan acid. A furanoid fatty acid has been isolated from Exocarpus cupressiformis seed oil. In two samples of this seed available to us we did not detect any furanoid acids but found 8-hydroxyoctadoc-trans-11-en-9-noic acid (5%).The methodology used in the isolation of furanoid acids also allowed the study of methyl-branched acids. Whilst confirming the wide distribution of three phytol-based acids in fish lipids we have also detected three other compounds which we believe are diunsaturated derivatives of 7,9-dimethylhexadecanoic, 7,9- and 9,11-dimethyloctadecanoic acids respectively. The opportunity was also taken to study the more common acids of some fish species not previously examined. Besides confirming the well-known differences between the lipids of freshwater and marine origin, we find a significant difference between the fatty acids of male and female fish of freshwater origin, with the female containing more n-3 polyene acids and less monoene acids than does the male. The n-3/n-6 ratio is the most significant feature distinguishing freshwater from marine fish lipids. The 10,13-, 9,12-, and 8,11-isomers of the C18 furanoid acids were prepared by one or more of the following methods. (i) Pd(II)-catalysed cyclodehydrogenation of oxygen-containing unsaturated acids, (ii) dehydration of diepoxides and dehydrogenation of epoxy alkenes with propyl iodide-sodium iodide-dimethylsulphoxide, and (iii) dehydration of endoperoxides. Synthesis of heterocyclic compounds by Pd(II)-promoted cyclization reactions is a fairly new development. The reactivity of various long-chain oxygenated esters with this unique reagent is discussed. The endoperoxide route is also novel and leads to speculation about the biosynthesis of natural furanoid acids. Recognition and identification of long-chain furanoid acids by their chromatographic and spectroscopic behaviour is discussed. Mass spectrometry is a powerful method of structure determination of these substances. Some chemical reactions of long-chain furanoid acids are also described.

No description available.

No description available.

Thesis presented in partial fulfillment of the requirements for the degree of Master of Technology (MTech) at Department of Chemistry, Faculty of Applied Science, Cape Peninsula University of Technology 2011 / Aromatic polyamides (PAs) are widely used as high-performance polymers in technical applications due to their unique combination of outstanding thermal, optical, mechanical and chemical properties. Although PAs are mostly utilized where strength or heat resistance is of primary concern, they also find use in other important applications such as in NOMEX membranes for desalination of brackish water or seawater. PAs do however have some disadvantages such as high melting points, high glass transition temperatures (T 9) and a limited solubility in most organic solvents, wh.ich makes their processing difficult. Polyureas (PUs) are generally known for their excellent thermal stability and high chemical resistance due to the presence of thermally stable bonds of aromatic or heterocyclic ring systems along their backbone. Both polymer systems are poorly researched when it comes*' the introduction of furan units into the chains. The same is valid for cases where two or more different diacids or diamines are incorporated. The aim of this study was therefore to investigate the influence of furan units in the polymer chains and the change in properties if the composition of starting materials is varied further. Nineteen PAs were prepared via the interfacial polymerization method and the homogeneous phase polymerization method. These polymers were prepared either with furan- or isophthalic acids in their chains and then compared with the copolymers, containing both diacids in different ratios. Products were characterized by various analytical techniques. Furanoyl-2,5-dichloride (FDC) and different amounts of isophthaloyl chloride (IPDC) - 0, 10, 30 and 50% - as the basic starting monomers were reacted individually with four diamines: m-phenylen diamine (MPD), 4,4'-diamino diphenylsulfone (DDS), 4,4'-diamino diphenylether (ODE) and 2,4-bis(4-aminophenyl)-6-phenyl-1,3,5-triazine-2,4,6-triamine (BAT) by interfacial or homogeneous polycondensation reactions. Two polyureas, starting with furanoyl-2,5-diazide (FDZ) and transformed into the diisocyanate were prepared by reaction with two diamines, namely MPD and DDS in homogeneous solution. The PAs and PUs were characterized by Fourier-Transform Infrared Spectroscopy (FTIR), Proton NMR CH), Carbon NMR C3C), Gel Permeation Chromatography (GPC), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The water up-take per polymer unit (mol water I repeat unit of the polymer) was measured. The values for 70% Relative Humidity (RH) were between 0.87 and 1 ~80 moles of water per repeat unit and for 43% RH between 0.40 and 1.35 mols.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2011. / Aromatic polyamides (PAs) are widely used as high-performance polymers in technical applications due to their unique combination of outstanding thermal, optical, mechanical and chemical properties. Although PAs are mostly utilized where strength or heat resistance is of primary concern, they also find use in other important applications such as in NOMEX membranes for desalination of brackish water or seawater. PAs do however have some disadvantages such as high melting points, high glass transition temperatures (Tg) and a limited solubility in most organic solvents, which makes their processing difficult. Polyureas (PUs) are generally known for their excellent thermal stability and high chemical resistance due to the presence of thermally stable bonds of aromatic or heterocyclic ring systems along their backbone. Both polymer systems are poorly researched when it comes to the introduction of furan units into the chains. The same is valid for cases where two or more different diacids or diamines are incorporated. The aim of this study was therefore to investigate the influence of furan units in the polymer chains and the change in properties if the composition of starting materials is varied further.

No description available.

Thesis (Ph.D.). / Written for the Dept. of Food Science and Agricultural Chemistry. Title from title page of PDF (viewed 2008/02/12). Includes bibliographical references.