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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.
41

Studies concerning the mechanism of osteolathyrogenic activity of beta-aminopropionitrile

Ehrhart, Leo Allen. January 1964 (has links)
Thesis (Ph. D.)--University of Wisconsin, 1964. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.
42

The preparation of substituted alpha halogen benzyl benzoates, and a study of the reactions of these compounds

French, Herbert Ephraim, Adams, Roger, January 1900 (has links)
Abstract of Thesis (Ph. D.)--University of Illinois, 1920. / Vita. Caption title: The reaction between acid halides and aldehydes. II. By H.E. French with Roger Adams. "Contribution from the Chemical Laboratory of the University of Illinois." "Reprinted from the Journal of the American Chemical Society, vol. XLIII, no. 3. March, 1921."
43

A study of some aldehyde reactions ...

Richlin, Isadore, January 1945 (has links)
Thesis (Ph. D.)--University of Chicago, 1941. / Reproduced from type-written copy. Includes bibliographical references.
44

Syntheses of amino acids from hydroxy aldehydes and ketones

Gast, Lyle Everett, January 1949 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1949. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves [i]-ii).
45

An approach toward the total synthesis of prefuroplocamioid /

Majkut, Yvette. January 2005 (has links)
Thesis (M.Sc.)--York University, 2005. Graduate Programme in Chemistry. / Typescript. Includes bibliographical references (leaves 115-121). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11848
46

On the behavior of various aldehydes, ketones and alcohols towards oxidizing agents ...

Denis, Willey Glover, January 1907 (has links)
Thesis (Ph. D.)--University of Chicago. / From American chemical journal, v. 38, p. 561-594. Also available on the Internet.
47

Aspects of the reactivity of coordinated ligands

Beddows, Claire J. January 1999 (has links)
No description available.
48

Concentration and derivatisation in silicone rubber traps for gas chromatographic trace analysis of aldehydes

Fernandes, Maria Jose 21 November 2005 (has links)
Please read the abstract in the section 00front of this document / Dissertation (MSc (Chemistry))--University of Pretoria, 2006. / Chemistry / unrestricted
49

The mechanism of permanganate oxidations : pivalaldehyde, benzaldehyde and p-nitro-phenyltrifluoromethylcarbinol.

Fleming, Donald George January 1963 (has links)
A study has been made of the potassium permanganate oxidation of three organic compounds: pivalaldehyde, p-nitrobenzaldehyde and p-nitrophenyltrifluoromethyl-carbinol. The permanganate-pivalaldehyde reaction has been investigated in the pH range 1 to 13. The results show that the reaction is first order in permanganate and aldehyde, that the oxidation by manganate is slower than that of permanganate by a factor of twenty five, and that the oxidation is general acid-catalyzed. The results in alkaline solution show some increase in rate but are not reproducible, which is most likely due to radical decomposition of the pivalaldehyde. Three mechanisms are discussed: Firstly, a typical general acid-catalysis scheme, secondly, one involving a tetragonal transition state and thirdly, one based on a hydride transfer. Of these, only the first two are able to accommodate the experimental evidence found earlier in the permanganate oxidation of benzaldehyde by Wiberg and Stewart (1). The autocatalysis exhibited by the permanganate benzaldehyde reaction has been studied at low pH. The autocatalysis has also been investigated with p-nitrobenzaldehyde in order to see if there is any substituent effect. Results show that the p-nitro aldehyde has a longer induction period. Moreover, it has been shown that overoxidation of the benzene ring rather than true autocatalysis has occurred. A radical chain mechanism has been put forward in an attempt to explain this observation. The permanganate oxidation of p-nitrophenyltri-fluoromethylcarbinol has been studied in 0.1 M sodium hydroxide in order to determine the mechanism of the reaction. A large enhancement in rate observed compared to rates found by Stewart and Van der Linden (2) in the permanganate oxidation of other substituted phenyltrifluoromethylcarbinols is good evidence for a reaction path involving hydrogen atom abstraction from the alkoxide to the permanganate ion. Such a mechanism is consequently favoured. / Science, Faculty of / Chemistry, Department of / Graduate
50

A Study of an aldehyde dehydrogenase from Pseudomonas aeruginosa

Von Tigerstrom, Richard G. C. January 1967 (has links)
An aldehyde dehydrogenase was found in cell extracts of Pseudomonas aeruginosa ATCC 9027 grown on several carbon sources. It was present in highest concentration in cell extracts after growth of the organism on ethylene glycol or ethanol . The enzyme from ethanol-grown cells was purified by protamine sulfate, ammonium sulfate, acetone, and isoelectric precipitation, ion exchange chromatography and gel filtration. After an eighteen-to twenty-fold purification with a twenty-three per cent yield of activity a homogeneous preparation was obtained, as evidenced by ultracentrifugation, electrophoresis, and other criteria. The enzyme was found to be unstable in crude preparations. This instability was overcome by the use of bisulfite buffer. The enzyme oxidizes a wide variety of aldehydes. The products of glycolaldehyde and glyceraldehyde oxidation were identified as the free acids. The pH optimum for the reaction was found to be between pH 8.0 and 8.6. The enzyme is more active with NAD⁺ as the hydrogen acceptor than with NADP⁺. Potassium or ammonium was found to be essential for activity. Less activity was obtained in the presence of rubidium. Aldehyde dehydrogenases from five other species of Pseudomonas were also activated by potassium. Michaelis constants for aldehyde substrates, NAD⁺, NADP⁺, and the activating ions were determined. In addition to the activating ion, a reducing agent was required for enzymatic activity. It could be replaced, in part, by EDTA or o-phenanthroline. No inhibition was observed with EDTA, but o-phen-anthroline inhibited the enzyme reaction in the presence of a reducing agent. However, zinc was not found to be present in the purified aldehyde dehydrogenase. Aldehyde dehydrogenase also was inhibited by iodoacetamide, iodoacetate, arsenite,Cu⁺⁺ , and p-chloromercuribenzoate. Enzymatic activity also was lost when trypsin was added to the enzyme preparation. This loss of activity and the inhibition by the alkylating agents were specifically prevented by the addition of the activating ion and NAD⁺ to the enzyme preparation. Some protection from digestion by trypsin was afforded by potassium alone. However, in the absence of NAD⁺ potassium accelerated the rate of inhibition by alkylating agents. A molecular weight of 200,000 was determined for aldehyde dehydrogenase by several methods. At low ionic strength the enzyme underwent a partial dissociation with loss of enzymatic activity. This dissociation could be reversed by increasing the salt concentration. Dissociation and association of the enzyme into subunits of approximately equal size could be followed in the ultracentrifuge and on starch gel electrophoresis. The dissociated form of the enzyme was isolated after starch gel electrophoresis and found to be completely inactive. Full enzymatic activity was obtained only when the associated enzyme was protected from oxidation. The enzyme was soluble below its isoelectric point (pH 4.8) but denatured as evidenced by sedimentation, diffusion, and viscosity studies. The molecular weight of the enzyme preparation at pH 3.0 was estimated to be approximately one-half of that found at pH 7.0.Aldehyde dehydrogenase contained relatively large amounts of all common amino acids. The lowest amount was obtained for cysteic acid: 23 to 24 residues per mole. Studies with ¹⁴C-iodoacetamide showed that the enzyme was completely inhibited when approximately three moles of iodoacetamide were taken up per mole of enzyme. Following chymotryptic digestion of labelled aldehyde dehydrogenase, a fraction containing a large percentage of the radioactivity was partially purified by ion exchange chromatography and gel filtration. This fraction contained one peptide species, or several very similar peptide species, probably derived from the active site of the enzyme. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate

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