• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 10
  • 2
  • 1
  • Tagged with
  • 14
  • 6
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The change in the order of catalytic action of lithium chloride, sodium chloride, magnesium chloride, and calcium chloride in the ketonic splitting of ethyl acetoacetate

Duff, Richard Dwight. January 1929 (has links) (PDF)
Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1929. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed September 15, 2009) Includes bibliographical references.
2

Steric hindrance in the ketonic splitting of substituted acetoacetic ester

Abshier, George Stanley, January 1933 (has links) (PDF)
Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1933. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed June 14, 2010) Includes bibliographical references (p. 68-62) and index (p. 63-64).
3

Catalytic studies on acetoacetic ester ...

Sullivan, Joseph John, January 1928 (has links)
Thesis (Ph. D.)--Johns Hopkins University, 1928. / Biography. Description based on print version record.
4

The influence of parathyroid hormone on the reduction of acetoacetate by succinate in isolated mitochondria

Martin, David Lee, January 1965 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 29-31.
5

The catalytic action of neutral salts : the effect of normal alkali sulphates on alkali acid sulphates in the ketonic splitting of ethyl acetoacetate

Goodhue, Elbridge Alvah. January 1927 (has links) (PDF)
Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1927. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed October 21, 2009) Includes bibliographical references.
6

Homogenous transition metal

Zeevaart, Jacob 26 October 2006 (has links)
Faculty of Science School of Chemistry 0100505x jzeevaart@csir.co.za / The application of homogenous transition metal catalysis to the arylation of enolates to develop new synthetic procedures which are more environmentally benign, atomefficient and economically viable than current methods was the motivation behind the current work. The specific choice of molecules with an aromatic group in the a- position of a ketone, carboxylic acid, amide or other electron-withdrawing group arose from the fact that many natural products, pharmaceutical actives and synthetic intermediates contain such a substructure while the syntheses of these substructures are often cumbersome. The application of homogenous catalysis to various types of enolates was explored and in the process several developments were achieved and discoveries made. These included the use of inorganic bases under phase transfer conditions for the Heck reaction of acrylic acid as well as the synthesis and application of phosphine and phosphite ligands in the Heck reaction of acrylic acid esters. The successful use of low palladium loadings (as low as 0.01mol%) in the arylation of diethyl malonate using aryl chlorides and the application to the synthesis of ketoprofen and phenobarbital was demonstrated. The novel application of palladium catalysis to the arylation of methanesulfonamides and the first example of a bromoindole derivative as the aryl halide partner in an enolate arylation reaction was demonstrated. Ligand-free palladium catalysed phenylation of pinacolone followed by Baeyer Villiger oxidation led to a proposed novel synthetic route to tert-butyl esters of 2-arylacetic acids. The palladium and copper catalysed arylation of acetoacetate esters, with in situ decarbonylation, provided a different route to 2-arylacetic acid esters which are useful in the preparation of non-steroidal anti-inflammatory compounds.
7

Structural and synthetic investigations of diterpenoid natural products from southern African marine invertebrates

Gray, Christopher Anthony January 2003 (has links)
This thesis is divided into two parts. The first part (Chapter Two) documents a bioassay guided investigation of the ethyl acetate extracts of four marine invertebrates from Mozambique (an Irciniid sponge, a Haliclona sp. sponge, an ascidian tentatively identified as Diplosoma sp., and the soft coral Cladiella kashmani). Eight known compounds [ilimaquinone (2.1), renierone (2.7), N-formyl-1,2-dihydrorenierone (2.8), 1,6-dimethyl-7-methoxy-5,8-dihydroisoquinoline-5,8-dione (2.9), mimosamycin (2.10) 7Z-allylidene-5-hydroxy-7,7a-dihydro-2H-cyclopenta[b]pyran-6-one (2.11), flaccidoxide (2.18) and 11S,12S-epoxycembra-1Z,3E,7E-trien-14S-ol (2.19)] and a new diterpene [13S,14R-diacetoxy-11S,12R-epoxycembra-1Z,3E,7E-triene (2.20)] were isolated and identified using standard spectroscopic techniques. Anomalies in the published spectral data of 2.1 and 2.8 were exposed and corrected, and the absolute stereochemistry of the cembrane diterpenes 2.18 and 2.20 established using the modified Mosher’s method. The comparative activities of the nine natural products against four cancer cell lines (A549, LOX, OVCAR3, SNB19) are reported. The second part of the thesis (Chapter Three – Chapter Six) is concerned with an ecological, structural and synthetic study of diterpenes from the endemic South African pulmonate limpet Trimusculus costatus. Two new labdane diterpenes [6b,7a-diacetoxylabda-8,13E-dien-15-ol (3.10) and 2a,6b,7a-triacetoxylabda-8,13E-dien-15-ol (3.11)] were isolated from T. costatus and evaluated for anti-feeding activity against the common predatory fish Pomadasys commersonnii. A strategy for the semi-synthesis of 3.10 from rhinocerotinoic acid (4.14), a diterpene reportedly present in the ubiquitous South African shrub Elytropappus rhinocerotis, was devised in order to allow further bioactivity tests to be performed and unequivocally assign the unknown absolute stereochemistry of the T. costatus metabolites. Attempts to isolate rhinocerotinoic acid from local specimens of Elytropappus rhinocerotis were unsuccessful, and as the repetition of a published synthesis of 4.14 from (-)-sclareol (4.15) gave rhinocerotinoic acid in unacceptably low yields with poor stereoselectivity, an improved synthesis of 4.14 is presented. Comprehensive studies using hispanone (5.1) as a model compound showed that 6,7-dioxygenated labda-8-enes could be prepared from compounds possessing a 7-oxo-labda-8-ene skeleton with some degree of stereocontrol. In the process, fourteen new hispanone analogues were prepared and most of these were tested for activity in a suite of ten agro-chemical assays. The novel compound 7b-hydroxy-9a-carbonitrile-15,16-epoxylabda-13(16),14-dien-6-one (5.34) exhibited significant activity against the crop fungus Phytophthora infestans and is currently being subjected to further agro-chemical tests. Unfortunately, the results from the oxygenation study performed on the model compound 5.1 could not be directly extrapolated to rhinocerotinoic acid. Attempts to prepare the naturally occurring 3.10 from 4.14 via an alternative route were unsuccessful but yielded an analogue of 3.10 in which the substituents at C-6 and C-7 are in a diequatorial rather than a diaxial configuration.
8

Manipulating the levels of ethyl acetate and isoamyl acetate formation during the production of wine and brandy

Bayly, Jennifer Carr,1977- 12 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The production of wine is a complex process, which involves the conversion of sugar in grape must to ethanol, carbon dioxide and other byproducts. The principal organism in winemaking is yeast, of which Saccharomyces cerevisiae is the most important due to its ability to survive winemaking conditions, its GRAS (Generally Regarded As Safe) status and the favourable flavours it imparts during the winemaking process. However, due to the demands of the consumer and the emergence of sophisticated wine markets, a demand is developing for specialised yeast strains with enhanced and new oenological properties. For these reasons, research into the contribution of wine yeast to the aroma bouquet as well the influence of wine or brandy maturation in wood on the aroma bouquet is important for consumer demands to be met. The fruity aroma of wine is associated with esters, which are produced during the alcoholic fermentation by yeast. Important acetate esters in wine and brandy are ethyl acetate, which has a fruity, solvent-like aroma, and isoamyl acetate, which has a banana-like aroma. These esters are produced through the action of acetyltransferases (AATases), which catalyse the reaction between a higher alcohol and acyl Coenzyme A. Esters are mainly a product of alcoholic fermentation. However, their concentration changes during wood maturation and it has been found that the concentration of acetate esters can increase during the maturation period. In this study, the aim was to investigate the influence of AATase I and AATase II, which are encoded by the ATF1 and ATF2 genes respectively, on the aroma bouquet of wine and brandy. Therefore, the first objective of this study was to clone the ATF2 gene from a commercial wine yeast strain and to overexpress this gene in a commercial wine yeast strain and in a wine yeast strain that already has the A TF1 gene overexpressed. Disruption cassettes were also designed in order to disrupt the ATF1 and ATF2 genes in a commercial wine yeast strain. The resultant recombinant wine yeast strains were used for the production of wine and brandy. GC analyses and tasting trials were conducted to determine the effect of the overexpression or disruption of these genes on the aroma bouquet of wine. The results obtained indicated that there are differences in the aroma bouquet of wine and brandy when changes are made in gene expression. The results indicated that the A TF1 gene plays a large role in the production of ethyl and isoamyl acetate. When this gene was overexpressed, the level of ethyl acetate was 5.6-fold more than that of the control and the level of isoamyl acetate was 3.5-fold higher than that of the control. However, no increase in ethyl acetate or isoamyl acetate was observed when the A TF2 gene was overexpressed. An increase in 2-phenylethyl acetate and diethyl succinate was observed in brandy, although there was a decrease in total ester concentration. A decrease in acetic acid was also observed in the brandy produced, which could be an indication of ester production. Similarly, no increase in ethyl acetate or isoamyl acetate was observed in the wine or brandy produced when both the ATF1 and ATF2 genes were overexpressed in a single yeast. Once again, a marked decrease was observed in acetic acid concentration in both the wine and brandy. In conclusion, it is clear that changes in gene expression can change the aroma profile of wine or brandy. However, the role of the ATF2 gene still remains unclear and further studies are needed to clarify its role in yeast. Future studies involving the effect of wood maturation on ester concentration will also be of importance, so that the winemaker or distiller can make a product that suits the ever-changing market. / AFRIKAANSE OPSOMMING: Die produksie van wyn is 'n komplekse proses wat die omskakeling van die suiker in mos tot etanol, koolstofdioksied en ander byprodukte tot gevolg het. Die hooforganisme betrokke in die wynmaakproses is gis, waarvan Saccharomyces cerevisiae as een van die belangrikste geag word as gevolg van die vermoë daarvan om onder die wynfermentasietoestande te kan oorleef, die "GRAS"-status (Generally Regarded As Safe) daarvan en die invloed wat dit op die aroma van die uiteindelike produk het weens die werking daarvan gedurende alkoholiese fermentasie. Die behoefte aan wyn met nuwe, verbeterde eienskappe het die vraag na meer gespesialiseerde gisrasse deur beide die verbruiker en nuwe wynmarkte gedurende die afgelope paar jaar drasties laat toeneem. Dit is om dié redes dat navorsing oor die bydrae van wyngis en houtveroudering tot die aroma van beide wyn en brandewyn so belangrik geag word. Die vrugtige aroma van wyn word geassosieer met die esters wat gedurende die alkoholiese fermentasie deur gis gevorm word. Die belangrikste asetaatesters in wyn en brandewyn is etielasetaat, wat vir 'n oplosmiddelagtige, vrugtige aroma bekend is, en isoamielasetaat, wat 'n piesangaroma veroorsaak. Die esters word geproduseer deur die werking van asetieltransferases (AATases), wat as katalis in die reaksie tussen 'n hoër alkohol en asetiel-Ko-ensiem A optree. Alhoewel esters hoofsaaklik 'n produk van alkoholiese fermentasie is, wissel die konsentrasie daarvan gedurende houtveroudering. Daar is gevind dat die konsentrasie van die asetaatesters gedurende die verouderingsproses kan verhoog. Die studie het ten doelom die invloed van AATase I en AATase II, wat onderskeidelik deur die ATF1- en ATF2-gene geënkodeer word, op die aroma van wyn en brandewyn te ondersoek. Die eerste doelwit van die studie was vervolgens om die ATF2-geen vanaf 'n kommersiële wyngisras te kloneer en dit daarna te ooruitdruk in 'n kommersiële wyngisras, asook die geen te ooruitdruk in 'n kommersiële wyngisras wat reeds die ATF1-geen ooruitdruk. Disrupsiekassette is ook vir die disrupsie van die ATF1- en ATF2-gene in 'n kommersiële wyngisras ontwerp. Die rekombinante wyngisrasse wat gedurnde die studie gemaak is, is vir die produksie van wyn en brandewyn gebruik. Gas chromatografise-ontledings en sensoriese evaluerings is ook op die wyn en brandewyn uitgevoer. Die resultate van die studie het bewys dat daar wel veranderings plaasvind wanneer 'n verandering in geenuitdrukking gemaak is. Die resultate het weereens bevestig dat die ATF1-geen 'n belangrike rol in die produksie van etiel- en isoamielasetaat speel. Wanneer die ATF1-geen ooruitgedruk is, is die etielasetaatproduksie 5.6 keer meer en die isoamielasetaatproduksie 3.5 keer meer as in die kontrole. Die ooruitdrukking van die ATF2-geen het geen verhoging in etielasetaat of isoamielasetaat of in totale esters in die wyn getoon nie, alhoewel die ras 2.7 keer meer diëtielsuksinaat geproduseer het. In die brandewyn wat geproduseer is met die gisras waarin ATF2 ooruitgedruk is, was daar wel 'n verlaging in die asynsuur, wat 'n aanduiding van estervorming kan wees, alhoewel die totale esters wat geproduseer is minder was as in die kontrole. 'n Verhoging in diëtielsuksinaat en 2-fenielasetaat is ook gevind. Daar is geen verhoging in etiel- of isoamielasetaat getoon wanneer die ATF1- en ATF2-geen saam ooruitgedruk is nie. Die ras het minder totale sure in wyn en brandewyn geproduseer en ook geen verhoging in totale esters getoon nie. Uit die resultate is dit duidelik dat veranderings in geenuitdrukking 'n verandering in die aromaprofiel van wyn en brandewyn kan veroorsaak. Die rol van dié A TF2-geen is nog steeds onduidelik en verdere studies sal moet plaasvind om die rol van die geen te verduidelik. Studies wat konsentreer op die invloed van houtveroudering op esterkonsentrasie is ook belangrik vir die toekoms, want dit sal die wyn- of brandewynmaker meer beheer oor die uiteindelike produk gee en daardeur die wyn- of brandewynmaker help om 'n produk te vervaardig wat sy mark bevredig.
9

Biosynthesis of Lycopodine

Castillo, Mariano 10 1900 (has links)
<p> The biosynthesis of lycopodine was studied by feeding radioactive acetate, acetoacetato, lysine and pelletierine to Lycopodium tristachyum. Partial degration of the radioactive lycopodine recovered from these experiments revealed specific incorporation of these precursors. The labeling pattern obtained is discussed in the light of the two major blogenetic hypothesis advanced for the Lycopodium alkaloids. </p> <p> The results obtained disproved Conroy's polyacetate hypothesis. They are consistent with the hypothesis that regards these alkaloids derived from lysine and acetate. </p> / Thesis / Doctor of Philosophy (PhD)
10

The Effects of a Ketone Body on Synaptic Transmission

Stanback, Alexandra Elizabeth 01 January 2019 (has links)
The ketogenic diet is commonly used to control epilepsy, especially in cases when medications cannot. The diet typically consists of high fat, low carb, and adequate protein and produces a metabolite called acetoacetate. Seizure activity is characterized by glutamate excitotoxicity and therefore glutamate regulation is a point of research for control of these disorders. Acetoacetate is heavily implicated as the primary molecule responsible for decreasing glutamate in the synapse; it is believed that acetoacetate interferes with the transport of glutamate into the synaptic vesicles. The effects on synaptic transmission at glutamatergic synapses was studied in relation to the ketogenic diet in Drosophila larvae for this thesis. Various measures of synaptic transmission were conducted. Acetoacetate decreased neurotransmission at the synapse. It was also found that acetoacetate has direct effects on the postsynaptic membrane, which indicates a novel role for the metabolite.

Page generated in 0.0653 seconds