Thesis (M.S.)--University of Wisconsin--Madison, 1960. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 15).

No description available.

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 129-136).

Thesis (Ph. D.)--University of Pennsylvania, 1895.

No description available.

Thesis (Ph.D.)(Chemistry)--University of Pretoria, 2005. / Includes summaries in English and Afrikaans. Includes bibliographical references. Available on the Internet via the World Wide Web.

The rate of exchange of the labile hydrogens of lysozyme was measured by out-exchange of tritium from solution samples and powder samples at varied hydration levels for pH 2, 3, 5, 7 and 10. The dependence of exchange of powder samples on the degree of hydration was the same at all pH, reaching rates of exchange equivalent to solution samples at 0.2 g H₂0/g protein (160 mol H₂0/mol protein), which corresponds to coverage of one-half the protein surface with monolayer water (Yang and Rupley, 1979). No additional hydrogen exchange was observed for protein powders equilibrated with higher water content. Considered in conjunction with other lysozyme hydration data (Rupley et al, 1983), this observation indicated that internal protein dynamics are not strongly coupled with surface properties. The use of powder samples offered control of water activity through regulation of water vapor pressure. The dependence of exchange rate on water activity was of low order, 2.9 average, and pH independent. This value, observed from 95 to 7 mol hydrogen remaining unexchanched/mol lysozyme, indicated that the rate determining step for protein hydrogen exchange is similar for all backbone amides and involves few water lilolecules. Powder samples were hydrated either by isopiestic equilibration against H₂S0₄ or NaOH solutions or by addition and mixing of solvent to rapidly reach final hydration. Samples hydrated slowly by isopiestic equilibration exhibited more exchange than was observed for samples of the same water content that had been hydrated rapidly by solvent addition. Conformational change with hydration was ruled out as an explanation of this difference by a powder to solution jump experiment at pH 5, which proved the rank order of exchange was preserved. The difference can be explained by salt and pH effects expected to contribute to exchange of the nearly dry protein. Solution hydrogen exchange measured using the same lyophilized protein as the hydration experiments was in good agreement with published data. Rank order was proven the same for all pH by solution pH jump experiments. The effect of ionic strength on hydrogen exchange was examined at pH 2 and pH 5 for protein solutions containing up to 1.0 M added salt. The influence of ionic strength was similar for both pH and exhibited a complex character, in contrast to the dependence of exchange observed for positively charged polypeptide models.

No description available.

This thesis covers the development of catalytic methodologies for the mild and chemoselective reductions of amides. The first part of the thesis describes the use of a Fe(II)/NHC catalyst for the deoxygenation of aromatic tertiary amides to corresponding amines. The protocol is characterized by low catalyst loading, mild reaction conditions and the use of air and moisture stable polymethylhydrosilaxane (PMHS) as the hydride source. The second part concerns the development of a protocol for the room temperature deoxygenation of a wide range of tertiary amides to amines using catalytic amounts of Et2Zn and LiCl together with PMHS. The system displayed high levels of chemoselectivity tolerating various reducible groups such as nitro, nitrile, and olefin functionalities, and was shown to be applicable for the reduction of aromatic, heteroaromatic and aliphatic tertiary amides. The attempts to expand the scope of the Fe-based protocol to accommodate benzylic tertiary amides led to the development of a transition metal-free catalytic system based on KOtBu for the formation of enamines. The final products constitute an important class of precursors for a wide range of valuable compounds in organic chemistry. Moreover, avoiding the use of transition metals in the protocol allowed the desired products to be obtained without the hazardous metal contaminants. The last chapter of the thesis describes the Mo(CO)6-catalyzed hydrosilylation of amides. The Mo-based catalyst was proven to mediate the deoxygenation of α,β-unsaturated tertiary and secondary amides to the corresponding allylamines without reduction of the olefinic bonds. Further development of the catalytic system revealed an unprecedented chemoselectivity in the hydrosilylation of aromatic and certain aliphatic tertiary amides in the presence of a variety of reducible groups along with aldehydes and imines that were tolerated for the first time. Moreover, it was possible to control the reaction outcome by variation of the reaction temperature to obtain either amines or aldehydes as the major products. The synthetic utility of the developed Mo(CO)6-catalyzed protocols was further demonstrated in the synthesis of the pharmaceuticals Naftifine and Donepezil.

Low molecular weight gelators (LMWGs) have gained much attention over the last few decades, because of their ability to form supramolecular architectures as well as their many potential applications in biomedical research and as advanced materials. Most of the gelators were discovered through serendipity, and their structural requirements are somewhat ambiguous. This is due, in part, to the fact that the supramolecular gelation phenomenon is not yet fully understood, though many structural classes have been found to be excellent organogelators. Carbohydrates are abundant natural resources that are useful in preparing advanced materials. We have previously showed that monosaccharide derivatives can form effective low molecular weight gelators for both organic solvents and aqueous mixtures. In this research, we have studied the gelation capability of several glucosamine derivatives. Several series of 4,6-O-acetal protected glucosamine derivatives were synthesized and screened for their gelation properties in several solvents.