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<p> This thesis describes an investigation into the effects of Lewis acid complexation on the photochemistry of α,β unsaturated carbonyl compounds.</p> <p> Initial studies involved the use of Nuclear Magnetic Resonance (NMR) and Ultraviolet (UV) spectroscopy in examining Lewis acid modification of the photostationary state for E/Z isomerization of various acyclic enones. The results obtained provide a good understanding of the origin of the perturbation of the photostationary state of these systems. In the course of these investigations, the question also arose as to the possible effects of complexation upon the photochemistry of cyclic enone systems where E/Z isomerization cannot occur, particularly whether this would catalyze [2+2] cycloadditions to the enone carbon/carbon double bond. Lewis acid complexed enones are widely used as activated dienophiles in Diels Alder reactions, and have been recently reported to serve as activated 'enophiles' in a photochemical dimerization of coumarin.</p> </p> The examination here is focused upon endo-tricyclo [5.2.1.02,6] deca-4,8-dien-3-one. (See Diagram in thesis). </p> <p> Reported here is a detailed investigation of the photochemistry of the AlEtCl2 complex of this compound, and the results are interpreted mechanistically. The reaction gives rise to a single product which reaches a photostationary state with the reactant complex. The isomerization is formally a [1,3] sigmatropic shift involving the isolated double bond. It seems likely however, to proceed by the formation of an allyl cation intermediate.</p> / Thesis / Master of Science (MSc)

<p> A series of 2-substituted Δ^3-1,3,4-oxadiazolines (i) were synthesized by oxidation of the corresponding hydrazones with lead-tetraacetate in alcohol, eq A. (See Diagram A in Thesis)</p> <p> These oxadiazolines, upon thermolysis, generated carbonyl ylide intermediates (ii). These ylides are known to undergo fragmentation into carbenes and carbonyl compounds, eq B. (See Diagram B in Thesis)</p> <p> A new series of products were found from the thermolysis of these types of oxadiazolines, ester azines iv and v. A possible mechanism for the formation of these ester azines involves carbene attack on the oxadiazoline to give an azomethine imine intermediate (iii) which can subsequently rearrange to give the azines and carbonyl compounds, eq C. (See Diagram C in Thesis)</p> <p> This mechanism is supported by the observation that the overall yields of ester azines rise with increasing initial concentration of oxadiazoline whereas the yield of propene, a rearrangement product of dimethyl carbene, falls with increasing initial concentration of oxadiazoline.</p> <p> The ester azines (R=CH3, CH2CH3 and CH(CH3)2) were found to be uniconfigurational and the E-configuration was assigned to ester azine iv and the E,E-configuration was assigned to ester azine v. Ester azines (R=C(CH3)3) were found to exist as configurational isomers. Equilibration studies were carried out on these ester azines and the thermodynamic parameters ΔG°, ΔH° and ΔS° were found for equilibration shown in eq D. (See Diagram D in Thesis)</p> <p> Changing the R' substituent of i to OCH2CCl3 or OCH2CF3 did not stop fragmentation of the derived ylide. Ester azines were found from the thermolysis of these oxadiazolines also. They were found to be uniconfigurational and were assigned the E-configuration.</p> / Thesis / Master of Science (MSc)

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Testing was conducted on the pre-prototype unit of an innovative indoor air pollution abatement system which used catalytic ozonation as a mechanism for oxidation and removal of organic contaminants. The system was evaluated for carbonyl production when the system was challenged with chemicals used to simulate polluted indoor air. Carbonyl compounds, which are potentially toxic partial oxidation products, were monitored using EPA Method I P-SA. The objectives of the study were to qualitatively and quantitatively determine if carbonyls were formed in the airstream when the system was operated, and if so, to determine what factors affected the concentrations of these compounds. Trials were conducted using benzene and 2-butanol as challenge chemicals. A variety of test conditions were used to determine factors affecting carbonyl concentrations, including temperature, presence of challenge chemicals, sample location, relative humidity, presence of ozone in the airstream, and two interaction variables. No carbonyls were detected in the airstream within the air cleaning system when benzene was used as the challenge chemical. When 2-butanol was used, four carbonyls were detected at various stages of the system, under varying conditions. The carbonyls detected during these trials were formaldehyde, acetaldehyde, acetone, and butanone. Statistical analyses of the data indicated that the pre-prototype unit of the air cleaning system caused increased levels of acetaldehyde and butanone, and possibly formaldehyde, in the airstream when challenged with 2-butanol. Acetone concentrations in the system were affected only by humidity conditions. / Master of Science

Electrochemical and infrared spectral data for a number of octahedral systems of the type LM(CO)₅ (M=Cr, Mo) and W; L=pyridine and quinoline), L₂M(CO)₄ (M=Cr, Mo, and W; L₂ =ethylenediamine, (pyridine)₂, and bipyridyl), (LM(CO)₄)₂ (M=Cr, Mo, and W; L=As(CH₃)₂ and P(CH₃)₂) and (LFe(CO)₃)₂ (L=SCH₃ , P(CH₃)₂ , and As(CH₃)₂) before and after electrochemical reduction are presented. Force constants are calculated using the Cotton-Kraihanzel force field and the results discussed in terms of sigma and pi-bonding. Infrared spectral data before and after electroche~ical reduction are also reported for a number of iron-olefin complexes of low symmetry. / M.S.

The addition of the Iithium dienolate 161a derived from ethyl 2-bromocrotonate (163) to several enones provided vinylcyclopropanes of type 165 which were converted by thermolysis to the corresponding cyclopentenes in an overall [2+3] annulation process. [see document for diagram of chemical compounds] The reactions of 161a with other electrophiles such as ketones, α,ß-unsaturated esters and α,ß-unsaturated aldehydes were also investigated. The possibility of asymmetric induction utilizing (-)-menthyl 2-bromocrotonate (169) was briefly investigated. An application of this methodology was expressed in the total synthesis of (-)- retigeranic acid (1), achieved in fifteen steps from menthene (187) in a convergent and enantioselective fashion. The key steps in this synthesis involved the vinylcyclopropanation of bicyclic enone 144 with the lithium dienolate of bromide 180, to provide vinylcyclopropanes 179 and, through their thermolytic rearrangement, the pentacyclic ketone 178, which was converted to the title compound. [see document for diagram of chemical compounds] / Ph. D.

Molybdenum hexacarbonyl supported on 𝛾-alumina is a precursor to an active olefin metathesis catalyst. Surface sites on the alumina act as coordinating ligands to stabilize various molybdenum subcarbonyl species. The formation of these species can be controlled by appropriate activation conditions. In particular, Mo(CO)₃(ads) can be quantitatively formed upon activation of Mo(CO)₆ on 𝛾-alumina at 100°C in flowing helium. In the reaction, three carbon monoxide ligands are replaced by either surface OH⁻ or O²⁻ depending on the degree of surface hydroxylation. This species has been shown to be active for olefin metathesis. The intent of this dissertation is twofold. The first part is an investigation of alternate, low temperature synthetic routes to Mo(CO)₃(ads) via ligand displacement reactions using the molybdenum tricarbonyl complexes, Mo(CO)₃(CH₃CN)₃ and Mo(CO)₃(η⁶-C₆H₆). Molybdenum hexacarbonyl can be impregnated onto 𝛾-alumina using an inert hydrocarbon solvent such as pentane or benzene and these solvents are also used to adsorb Mo(CO);(11°·C6H„). However, a polar solvent such as acetone is necessary in the case of Mo(CO)₃(CH₃CN)₃. The resulting surface species using these complexes are characterized by FTIR, reaction stoichiometry and propylene metathesis activity and are compared with results obtained for 𝛾-alumina supported Mo(CO)₆. In order to interpret the results for Mo(CO)₃(CH₃CN)₃, the interaction of acetone with 𝛾-alumina was investigated since acetone is highly reactive with the surface. The results of this in situ FTIR-MS study of acetone on 𝛾-alumina are also reported. The second part of this dissertation involves using cross polarization-magic angle spinning ¹³C NMR to probe the dynamic natures of Mo(CO)₃(ads) and Mo(CO)₅(ads). Crystalline samples of metal tricarbonyl complexes, which serve as model compounds for Mo(CO)₃(ads), are characterized by variable temperature CP-MAS ¹³C NMR in order to determine the presence of motional processes involving the carbonyl ligands. These findings yield additional information about the nature of molybdenum subcarbonyls on 𝛾-alumina. / Ph. D. / incomplete_metadata