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  • 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

Synthesis of a Novel Tocopherol/Carotenoid Derivative

Haugland, Marius Myreng January 2012 (has links)
The goal of this work is the synthesis of a tocopherol/carotenoid hybridderivative (1, figure II). The novel derivative is believed to exhibitsynergistic antioxidant effects between its chromanol and polyene consituents.The synthesis of 1 was completed up to and including theimmediate precursor 12.Commercially avaliable Trolox (7) was reduced by Red-Al® to 8(step a) in 95% yield. Chromanol aldehyde 9 was formed by Swernoxidation of 8 in 65% yield (step b). Wittig reaction between 9 andphosphonium salt 10 afforded 11 in 33% yield and varying cis : transratio (step c), and subsequent elongation produced 12 (14% yield, stepd). The Wittig reactions were performed with reflux and microwaveirradiation.Various attempts at protecting the phenolic group in intermediate8 by silylation or benzylation did only lead to formation of 8B.Oxidation of 8 by the Dess-Martin oxidation formed the unexpectedquinone-like derivative 27. Efforts to protect the phenolic group in intermediate9 by benzoylation and silylation only produced 9A, foundto be unsoluble in all common laboratory solvents.
2

Fremstilling av propargylestere og anvendelse i gullkatalyserte reaksjoner / Preparation of Propargyl Esters and Applications in Gold-catalyzed Reactions

Tungen, Jørn Eivind January 2011 (has links)
Hovedmålet i masteroppgaven har vært å utforske nye gullkatalyserte reaksjoner og anvendelser av propargylestere og allenestere. Allen 14, ble syntetisert fra propargylbromid over to trinn, ved en kjent prosedyre. Kationiske gullkomplekser har en sterk alkynofil karakter som aktiverer alle typer π-systemer for nukleofilt angrep. Dette gjør allen 14 godt egnet som substrat i gullkatalyserte transformasjoner. E-Dien 22a-b, samt Z-dien 23a-b, ble syntetisert i en stereoselektiv gull(I)katalysert reaksjon. Dette er første gang diener har blitt fremstilt fra 2-substituerte allenestere, og det ble observert en høyere Z-selektivitet enn hva som tidligere har blitt observert for usubstituerte allenestere. Dien 22a og 23a ble isolert i et utbytte på henholdsvis 35% og 33% med et E/Z-forhold på 47:53. For dien 22b og 23b var E/Z-forholdet 52:48, og de ble isolert utbytter på 38% og 28%. Elektrofil addisjon til allen 14, etterfulgt av et 1,2-arylskift, ga aldehyd 25 i et utbytte på 45%. Tre nye forbindelser er blitt fremstilt ved en helt ny metode for gull(I)katalysert jodhydroksylering av allenestere. Vinyljodid 24 og 26 ble dannet i utbytter på henholdsvis 59% og 39%, mens omleiret produkt 27, ble isolert i et utbytte på 20%. Syklopropylforbindelse 28 ble syntetisert i en ny gull(I)katalysert ”tandem”-syklopropaneringsreaksjon, fra propargylester 4, i et utbytte på 34%.Fire nye syklopropylforbindelser 18a-b og 19a-b har blitt syntetisert. Disse er dannet i en sykliseringsreaksjon mellom vinylester 17 og propargylester 1b eller 4. Syklopropylforbindelse 18 og 19 er isolert i utbytter på henholdsvis 52% og 76%. Et kiralt NHC-basert gullkompleks 41 har blitt syntetisert, og testet som gull-ligand i syklopropanerings-reaksjon. Det ble funnet et enantiomert overskudd på 5% for cis-forbindelse 43a, og et enantiomert overskudd på 6% for trans-forbindelse 43b. Dette er første gang en kiral NHC-basert gullkatalysator er blitt testet i en gullkatalysert asymmetrisk syklopropaneringsreaksjon.
3

Fremstilling av et kiralt triazoliumbasert NHC-salt og anvendelse i asymmetrisk syntese / Preparation of a Chiral Triazoliumbased NHC-salt and Applications in Asymmetrical Syntheses

Solvang, Tina January 2011 (has links)
Et kiralt triazoliumbasert N-heterosykliskkarben-salt (NHC) 1 har blitt fremstilt fra L-fenylalanin 2 og fenylhydrazinhydroklorid 12 i en synteserute som går over fem trinn, og med et totalutbytte på 10%. NHC-salt 1 er blitt testet som organokatalysator i en sykliseringsreaksjon mellom aldehyd 4 og keton 5. Produktet, butyrolakton 6, ble dannet i et trans/cis-forhold på 59:41, og med et enantiomert overskudd på henholdsvis 10% og 19% for trans- og cis-forbindelse 6a og 6b.NHC-salt 1 ble testet som ligand i en gullkatalysert syklopropaneringsreaksjon. Gullkatalysator 15a og 15b ble syntetisert fra NHC-salt 1 og 16 ved hjelp av Ag2O og AuCl(Me2S) i et utbytte på henholdsvis 82% og 85%. Syklopropaneringsreaksjon mellom alkyn 18 og alken 19 ga syklopropylforbindelse 20 i et trans/cis-forhold på 41:59 for gullkatalysator 15a og 38:62 for gullkatalysator 15b. Gullkatalysator 15a ga et enantiomert overskudd på 8% og 6% for henholdsvis trans- og cis-forbindelse 20a og 20b. Gullkatalysator 15b ga et enantiomert overskudd på 10% og 9% for de samme forbindelsene. Dette er første gang en kiral triazolbasert NHC-gullkatalysator har blitt brukt i asymmetrisk syntese.
4

Screening of Inhibitors for Amine Degradation

Elnan, Jørund January 2012 (has links)
Hindering the degradation of amines in the CO2-capturing process is important both for economical purposes when it comes to loss of solvent and impacts on the process, and to prevent emissions of volatile degradation compounds such as ammonia, nitrosamines and formaldehyde. To prevent the absorbent from degrading, either a non-degrading absorbent can be developed or a degradation inhibitor can be added to minimize the degradation. The degradation inhibitors tested in this thesis are meant to inhibit the oxidative degradation that mainly occurs in the absorber. The carbamate polymerization degradation due to CO2 and temperature has to be addressed on its own. The inhibitor screening apparatus was new, and a part of the assignment was testing this setup. The first experiment conducted on the inhibitor screening apparatus used a gas blend of 6% O2/2 % CO2 (N2 balance). This did not give enough degradation, which caused the need for rebuilding the rig. In the other experiments on the screening apparatus, a gas composition of 98 % O2/2 % CO2 was used to get sufficient amount of degradation for inhibitor screening. Inhibitor screening experiments were done using 150 mL of a 30 weight% (wt%) 2-aminoethanol (MEA) solution loaded with 0,4 mol CO2/mol MEA, at 55 °C with a gas flow of 10 mL/min. To test the stability of the inhibitors at higher temperature, thermal experiments with inhibitors were conducted. 7 mL solution was filled in stainless steel cylinders and heated at 135 °C, for a period of five weeks. The solution was 30 wt% MEA loaded with 0,5 mol CO2/mol MEA. Hydrazine was screened for inhibitory effect using a circulative closed loop apparatus because of the hazards related to this compound. The experiment was run with air, using a 30 wt% MEA solution loaded with 0,4 mol CO2/mol MEA, at 55 °C. Since experiments with both 6 % and 98 % oxygen were conducted, it was natural to compare the impact of oxygen concentration on the degradation products. Results indicated that 2-oxazolidinone (OZD) was preferred at the conditions with high oxygen, while N-(2-hydroxyethyl) glycine (HeGly) concentrations increased with decreasing oxygen content. The effect of metals on product composition was also investigated. The degradation compound N-(2-hydroxyethyl) imidazole (HEI) seems to be dependent on the metal concentrations, increasing in the presence of metals. For the inhibitors screened, the inhibition ranged from 23,59-67,81 %. Two compounds gave an increase in degradation. 1-hydroxyethane 1,1-diphosphonic acid (HEDP) was the only chelating agent stable at thermal conditions. The inhibitors did not appear to have a substantial effect on the carbamate polymerization. Quantification of degradation compounds in the samples was done using liquid chromatography-mass spectrometry (LC-MS) and anion chromatography-electrochemical detector (IC-EC). Amine loss and CO2-loading were determined using titration methods. Metal concentrations were determined using inductively coupled plasma-mass spectrometry (ICP-MS). Some analyses were done gravimetrically while others were done volumetrically. For comparison purposes, simple density measurements were done, and the data converted according to the amine loss in the sample.The initial intention was to use gas chromatography - mass spectrometry (GC-MS) to analyze the samples from the thermal experiments. The system was however not operable during the time available. ICP-MS analysis was not done in time for the last experiment. Ammonia analyses were not conducted in time for this thesis.
5

Synthesis of a Precursor for a Carotenoid Cationic Lipid

Vo, Mong Truc January 2012 (has links)
The goal of this work was the synthesis of a carotenoid cationic lipid for the research of carriers of nucleic acids into defective cells via transfection therapy. In the course of this project a precursor for the carotenoid cationic lipid was successfully obtained, but because of the limited time the synthesis of the carotenoid cationic lipid itself was not performed.
6

Gold(I) Catalyzed Tandem Cyclization Reactions

Rajinder Kaur, Maya January 2012 (has links)
Through this study it has been observed that in contrast to propargyl esters which give cyclopropyl products, the high reactivity of propargyl acetals allows a new tandem cyclization to take place, resulting in bicyclic products. It has also been found that steric effects may cause propargyl acetals to react by unexpected pathways. NMR studies confirmed a particularly high reactivity of propargyl acetal compared to propargyl ester. These results show how molecular diversity can easily be achieved by varying the substrates in gold(I) catalysis.
7

Vinyl Amide Reactions in the Presence of Gold(I) Catalyst

Blakstad, Guro January 2012 (has links)
Reaksjoner med vinylderivater i nærvær av gull(I)katalysator. Sykloaddisjoner og dimeriseringsreaksjoner er studert.

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