• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 179
  • 24
  • 23
  • 9
  • 9
  • 8
  • 8
  • 8
  • 8
  • 8
  • 8
  • 4
  • 4
  • 2
  • 2
  • Tagged with
  • 331
  • 88
  • 41
  • 33
  • 29
  • 26
  • 23
  • 21
  • 20
  • 15
  • 15
  • 15
  • 15
  • 14
  • 13
  • 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.
161

Accelerated decomposition of peroxynitrite by Ketones and Aldehydes

鄧陽招, Tang, Yeung-chiu, Dennis. January 1999 (has links)
published_or_final_version / Chemistry / Master / Master of Philosophy
162

Catalytic tandem nucleophilic addition for the synthesis of heterocycles

Nguyen, René-Viet, 1981- January 2008 (has links)
Classical methodologies for carbon-carbon bond formation often require stoichiometric amount of reagent to prefunctionalize a C-H bond. Such methods generate a lot of waste and are therefore not atom-efficient. On the other hand, the use of catalysts for the direct use of C-H bond without prior functionalization is a more desirable approach for carbon-carbon formation. For example, an overall addition reaction is 100% atom economical. This thesis focuses on the catalytic addition of the three types of C-H bonds (Csp-H, Csp2-H and Csp3-H) to unsaturated molecules such as conjugated dienes, imines and carbon dioxide to form heterocycles. / The first chapter describes the direct single addition of 1,3-diketones (Csp3- H bond) to conjugated dienes and enol ethers catalyzed by gold(III) chloride and silver(I) trifluoromethanesulfonate. The reaction is highly regioselective, although the overall yields are modest (up to 70%) due to the oxidative nature of the catalysts. Under certain conditions, the addition product undergoes a subsequent cyclization to form dihydrofurans. This tandem addition/cyclization reaction is catalyzed by trifluoromethanesulfonic acid and is discussed in the second part of the chapter. / The second chapter deals with the addition of phenol derivatives (C sp2-H bond) to conjugated dienes catalyzed by gold(III) chloride and silver(I) trifluoromethanesulfonate. The reaction affords dihydrobenzofurans via an intramolecular O-H cyclization. Investigation into the sequence of the reaction shows that the C-C bond is formed before the C-O bond. / The third chapter presents the addition of terminal alkynes (Csp-H bond) to imines catalyzed by cheap copper(I) iodide salt via a three-component coupling of salicylaldehyde derivatives, secondary amines and alkynes. Microwave irradiation is used which considerably shortens the reaction time and eliminate the use of solvents. Dihydrobenzofurans with an exocylic double bond are formed via an intramolecular O-H cyclization. The use of aliphatic alkynes molecules containing a heteroatom is critical to the success of the reaction. / Finally, in the last chapter, the addition of terminal alkynes (C sp-H bond) to carbon dioxide (catalyzed by gold(I) chlorotriphenylphosphine and silver trifluoromethanesulfonate) is applied to the synthesis of arynaphthalene lactones via a multicomponent coupling of phenylacetylene, CO2 and 3-bromo-1-phenyl-1-propyne.
163

Chelate-exchange reactions of l-diketonates of zinc, cadmium and several transition metals in benzene and methanol: K thermodynamic properties and titrimetric applications.

Amboise, Marius d'. January 1973 (has links)
No description available.
164

New functionalised 3-hydroxypyridines

Chubb, Richard William John January 2001 (has links)
This thesis is concerned with the synthesis and reactions of functionalised 3- liydroxypyridines, in particular 2-aryl- and 2-heteroary 1-3-liydroxypyridines by non- coupling methodology, from furan precursors. Chapter 1 reviews the synthesis and reactions of 3-hydroxypyridines. Chapter 2 describes the synthesis of 2-acylfurans via differing methods, which include acylation of the furan nucleus, Grignard reactions of furaldehydes and, most notably, reaction of lithiofurans with reagents containing a nitrile component. Chapter 3 concerns reaction of acylfurans with ammonia at high pressure and temperature to produce 3-hydroxypyridines. We have found that this ring expansion is able to withstand many differing substituents including bromine. Further development of the pyridine ring system involves reaction of the ring atoms or substituents, including protection of the hydroxy group. This ring expansion was used in the development of a novel azabenzotriazole starting from a simple furan compound, and this is reported in Chapter 4.The methodology described in this thesis is versatile and has allowed access to a range of novel pyridine derivatives in synthetically useful quantities which should be of interest in many areas of organic chemistry.
165

Development of a method for the LCMS determination of vicinal diketones in beer

Blanchette, Maxime. January 2006 (has links)
No existent analytical method allowed the determination of the vicinal diketones (VDK), 2,3-butanedione (diacetyl) and 2,3-pentanedione, by liquid chromatography/mass spectrometry (LC/MS). An LC/MS method was developed for the simultaneous determination of diacetyl and 2,3-pentanedione in beer. A method allowing the determination of the amino acids (AA) related to the formation of VDK during fermentation was also developed. VDK were derivatized with o-phenylenediamine (OPDA) to form quinoxaline compounds. The reaction of VDK with OPDA was studied to optimize reaction time. Conversion of the diacetyl precursor, alpha-acetolactate, was tested using multiple oxidative decarboxylation techniques. Attempts were also made to determine simultaneously the AA, leucine, isoleucine and valine with the VDK. Simultaneous determination was unsuitable for the AA levels found in beer fermentation and separate methods for the determination of AA were developed. Total VDK were measured over a concentration range of 10 mug/L to 10 mg/L with less than 10% variation. These analytical methods were tested using a laboratory scale experiment to assess the impact of fermentation temperature on total VDK production and AA absorption. Samples collected in a local brewery were analyzed for total VDK using the developed method.
166

Conformational analysis of 2-aryl-3-methylpropyl derivatives by nuclear magnetic resonance spectroscopy: The photochemistry of some unsaturated ketones

Carlson, David Arthur January 1970 (has links)
Typescript. / Thesis (Ph. D.)--University of Hawaii, 1970. / Includes bibliographies. / 2 pt. in 1 v illus., tables
167

The alkylation and thermal elimination of - chloro sulfoxides and the synthesis and rearrangement of epoxy sulfoxides /

Prachar Thamnusan. January 1978 (has links) (PDF)
Thesis (M.Sc. (Organic Chemistry)) -- Mahidol University, 1978. / Supported by the University Development Commission.
168

A temperature and pressure dependent kinetics study of the gas-phase reactions of bromine (2P3/2) and chlorine (2PJ) atoms with methylvinyl ketone

Huskey, Dow T. January 2008 (has links)
Thesis (M. S.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Dr. Paul Wine; Committee Member: Dr. Jean-Luc Brédas; Committee Member: Dr. Rigoberto Hernandez
169

I, the reducing action of compounds containing the group]CH. OMgI; II, the reduction of aldehydes by the binary system, magnesium iodide + magnesium ...

Shankland, Rodney Veeder, January 1930 (has links)
Thesis (SC. D.)--University of Michigan, 1930.
170

Reduction of aromatic 1, 2-diketones by the binary system, magnesium iodide (or bromide) + magnesium ...

Van Natta, Frank John Lewis, January 1929 (has links)
Thesis (Ph. D.)--University of Michigan, 1928.

Page generated in 0.0281 seconds