Thesis (Ph. D.)--Catholic University of America, 1912. / Biography.

Thesis (PH. D.)--Catholic University of America, 1912. / Biography.

Inaug. Diss.--Kiel. / Lebenslauf.

The enolization of acetone is subject to both general acid and general base catalysis, eqs. [1.10] and [1.78]. The Bronsted equation relates the catalyzing power of the acid or base to the equilibrium acid or base strength of the species involved, eqs. [1.14] and [1.13]. [Formula Omitted] This work involved measuring enolization rate constants for over 130 acid and base catalysts. These include monoprotic and diprotic carboxylic acids, phosphonic acids, carboxylate monoanions and dianions and phosphonate dianions. A number of the conjugate bases of the diprotic acids, i.e. bifunctional monoanions, were also examined. A number of effects were probed by an examination of the resulting Bronsted plots. In the case of general acid catalysis, a number of sterically crowded catalysts displayed enhanced catalytic activity. That is to say, they are more effective in the enolization process than their equilibrium acid strengths would suggest. This result was evident in both carboxylic acid and phosphonic acid catalysis, but not in general base catalysis. The role of steric factors in these processes is unclear. A group of bifunctional monoanions are shown to act as general acids in the enolization process. A comparison of 5- and 2 - substituted isophthalate monoanions reveals a steric accelerating effect for the 2-substituted species, a result consistent with earlier observations. Species with polarizable substituents are better catalysts, in both acid and base catalysis, and this result is explained. A set of carboxylate dianions, whose conjugate monoanions possess no hydrogen-bonding, form a reasonable Bronsted line. A pair of dianions deviate below this line, and the degree of deviation is shown to be related to the degree of hydrogen-bonding present in the conjugate monoanions. The group of phosphonate dianions gives a curved Bronsted plot suggesting a changing transition state as the base strength of the catalyst is varied. In terms of the Hammond postulate, a more favourable proton transfer (involving a stronger base) is leading to an earlier, more reactant-like transition state i.e. the proton transfer is occurring earlier along the reaction coordinate. The curvature is analyzed in terms of Marcus Theory and gives experimental support to the concepts of transition state energetics that are encompassed in the Hammond and Marcus models. A correlation of primary isotope effects with the curved Bronsted line is presented and this further maps out the varying degrees of proton transfer in the transition state. A number of other examples of experimental evidence for the Hammond postulate are presented. Carboxylic monoprotic acids, free from both polarizability and steric factors, appear to form a curved Bronsted line. While the curvature is in the direction predicted by Marcus Theory, primary isotope effects suggest that a changing transiiton state is not a cause of the curvature. As well as the topics mentioned here, a number of other facets of the reaction are discussed, including electrostatic factors. It is shown, for example, that including catalysts of varying charge in a single Bronsted correlation must be done with caution. / Science, Faculty of / Chemistry, Department of / Graduate

Thesis(M.S.)--Case Western Reserve University, 2010 / Title from PDF (viewed on 2009-11-23) Department of EMC - Mechanical Engineering Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center

Thesis (M.S.)--Ohio State University, 1954. / Available online via OhioLINK's ETD Center

Thesis (Ph. D.)--Catholic University of America. / Biography.

Thesis (Ph. D.)--Catholic University of America. / Biography.

Desonide, a new topical anti-inflammatory and antipruritic steroid, has been investigated for its clinical, vasoconstrictor and in vitro percutaneous penetration properties, and compared to betamethasone 17-valerate, triamcinolone acetonide and hydrocortisone. The clinical and vasoconstrictor bioassay tests place desonide quantitatively among the most effective topical anti-inflammatory agents, possibly because of its relatively rapid skin penetration rate. The significance of the study is (a) it provides definitive data on topical anti-inflammatory effectiveness of desonide and (b) it reveals that, contrary to current opinion, fluorination of the steroid molecule may be unnecessary for topical anti-inflammatory activity, and that 9 °C-fluorination in prednisolone acetonides impedes rather than favours their skin penetration rates. New data on octanol/water partition coefficients and an unsuccessful effort of adopting the Martin (1968) oxime derivative spectrophotofluorometric technique for desonide assays are also included. / Pharmaceutical Sciences, Faculty of / Graduate

Thesis (MSc (Chemistry))University of Limpopo, 2011. / Isolation and characterization of antibacterial and antioxidant compounds present in Combretum collinum Sub specie Suluense Leaf extracts of six different plants, many of which are used by traditional healers, were screened for antibacterial activity. Ethyl acetate and Methanol extracts of Adina microcephaha, Combretum aurea, Combretum bracteosam, Combretum collinum, Filicium decipiens and Ficus moraceae were screened. Of these acetone extracted the highest mass of 118 mg from Filicium decipiens as compared to the extracts from the Adina microcephala, Combretum aurea, Combretum bracteosum, Combretum collinum and Ficus decipiens. Two unknown compounds were isolated, characterized and their minimum inhibitory concentrations were determined; compound A = 0.5689 mg/ml and compound E = 1.479 mg/ml. The chemical structure proposed for unknown compound A from Combretum collinum subsp suluense was determined by correlation of HNMR, FT-IR and GC-MS data. The chemical structure of compound E was not proposed because it was masked by a phthalate pollutant, the structure of which was confirmed by correlation of GC-MS, FT-IR and 1HNMR data. O O O O Proposed structure of compound from vial A Proposed structure of phthalate pollutant