Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Gall, Ken; Committee Member: Graham, Samuel; Committee Member: Jacob, Karl; Committee Member: Perry, Joe; Committee Member: Pierron, Olivier.

Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010. / Committee Chair: Marder, Seth; Committee Co-Chair: Perry, Joseph; Committee Member: Dickson, Robert; Committee Member: El-Sayed, Mostafa; Committee Member: Riedo, Elisa. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Possible synthetic approaches to the pyrrolo[2,1-b]thiazole system have been investigated involving the mode of addition of thiazoles to dimethyl acetylenedicarboxylate. A number of thiazoles were allowed to react with the ester and the reactions were found to be remarkably solvent dependent. Dimethylformamide and methanol (or acetonitrile) were found to be specific for the formation of a particular class of adduct. The structures of the various adducts were extensively investigated by proton magnetic resonance spectroscopy. It was found that the proton magnetic resonance spectra of the unsubstituted and monosubstituted thiazole adducts, prepared in dimethylformamide, were different from the resonance spectra of the 2,4-disubstituted thiazole adducts. Various compounds were prepared for use as proton magnetic resonance reference compounds giving strong support for the structures proposed. Various degradative methods were employed in order to gain additional evidence for the proposed structures. Trimethyl pyrrolo[2,1-b] thiazole-5,6,7-tricarboxylate v/as isolated in low yield from thiazole and dimethyl acetylenedicarboxylate in methanol. Various attempts to decarboxylate the 6-carboxylic acid and isolate the parent pyrrolo[2,1-b] thiazole in good yield were unsuccessful. The 6-carboxylic acid methyl ester was reduced to 6-methyl-pyrrolo[2,1-b] thiazole with the lithium aluminium hydride/aluminium chloride complex. 2-Methylthiazoliiie formed isolable adducts with dimethyl acetylenedicarboxylate but the proton magnetic resonance spectra showed that they possessed a different structure from the corresponding 2-methylthiazole adducts. Thiazoles did not react with ditetrahydropyranyl acetylene-dicarboxylate nor with a saturated solution of acetylene in N-methyl-2-pyrrolidone. The addition reactions of thiazoles were extended to methyl propiolate which was found to be less reactive than dimethyl acetylenedicarboxylate. Adducts could only be isolated in low yield from thiazole, 2,4-dimethylthiazole and 2-methylthiazole. The structures proposed for these adducts did not bear analogy to those isolated from dimethyl acetylenedicarboxylate. Further investigations into the preparation of pyrrolo[2,1-b] thiazoles were attempted using other methods. Low yields of 6-substituted pyrrolo[2,1-b] thiazoles were obtained from the cyclisation of acetonyl and phenacyl-2-alkylthiazolium salts in aprotic solvents. Attempted cyclisations of 3-acetonyl-2-niethyl-thiazolium perchlorate with thionyl chloride and 3-formylmethyl-2-methylthiazolium chloride with sodium acetate and acetic anhydride gave only traces of the corresponding pyrrolo[2,1-b]thiazoles.

This thesis is divided into three sections, Parts 1, 2 and 3. Each part is divided into a number of principal sections, prefixed by capital letters, and these sections are further divided into sub-sections prefixed by Roman numerals or small letters. Part 1A deals with the relationship between azulene, indolizine and pyrrolo [2,1-b] thiazole, while part 1B consists of a review of the preparation and properties of thiones and thials. Part 2A-C is a discussion of results achieved in the course of investigations into the reactivity of indolizines and pyrrolo [2,1-b]-thiazoles towards electrophilic reagents. In Part 2D are described synthetic routes to some stable heterocyclic thiocarbonyl compounds, together with a preliminary investigation into the physical and spectral properties of these compounds. Part 3 is devoted entirely to a description of experimental details and is a complement to Part 2. Where reference is made to the chemical literature, this is indicated by a number in superscript, a key to which can be found at the end of part 3. The structural formulae which have been produced for illustrative purposes have been assigned Roman numerals, which correspond to the numbers which have been assigned to the relevant compounds in the text. The structure keys to Parts 1 and 2 are distinct. The structure key to part 3 is the same as that for Part 2.

A number of synthetic approaches to the pyrrolo [2.1-b] this sole system have been investigated. Two useful preparative methods have been developed. The first is based on the cyclisation of the quaternary salts from 2-methyl- or 2-methylene- thiatoles and o-haloketones using sodium acetate in acetic snhydride and leads to a variety of 6-alkyl and 6-aryl pyrrolo [2,1-b] thiszoles. The second method involves the thermal cyclisation of the product from 2'-thiaxolyl lithium and epichlorohydrin and affords the parent base, although in low yield. An investigation of the properties of the pyrrolo [2,1-b] thiazole system has been carried out. The ready formation of trint trobenzene complexes of the alkyl pyrrolo [2,1-b] thiazoles together with the evidence afforded by ultra-violet and nuclear magnetic resonance spectroscopy, is indicative of the aromatic nature of the system. Pyrrolo [2,1-b] thiezoles readily from salts with picric and perchloric acid. Nuclear magnetic resonance studies have shown that this process, the simplest form of electrophilic attack, involves the 5-position of the nucleus. A brief examination of the electrophilic substitution reactions of 6-methylpyrrolo [2,1-b] thiazole has shown that substitution takes place extremely readily and that the first substituent group enters at position 5 the second at position 7. An examination of the properties of groups attached to the nucleus has been limited to methyl groups and it has been found in contrast to the analogous indolizine system a methyl group in the 3-position of pyrrolo [2,1-b] thiazole is not sufficiently acidic to allow proton abstraction by n butyl lithium. However methyl groups at the 5- and 7-positlon readily suffer abstraction of a hydride ion in analogy to the methyl indolizines. The results obtained, taken as a whole, indicate a lower degree of polarization of the ground state of pyrrolo [2,1-b] thiazole than exists in indolizine. Furthermore in the transition state of electrophilic substitution at positions 5 and 7 there appears to be a lesser degree of accommodation of the positive charge on the thiazole ring as compared with similar inter-mediates in the indolizine series.

No description available.

Thiourea, 1-substituted thioureas and 1,3-disubstituted thioureas react under acidic or basic catalysis with 1,2-diketones to give a wide variety of products. The nature of the product or products depends on the conditions used, the degree of substitution of the thiourea and on the nature of the aromatic or aliphatic groups attached to the dicarbonyl unit of the diketone. The mechanisms of formation of the various products have been investigated by a variety of techniques, including the determination of rate equations by ultraviolet spectroscopy, the influence of side group substituents on the rate and course of the reactions and the synthesis of putative Intermediates on the reaction pathway. The single most informative technique used was, without a doubt, the detection of low concentrations of transient intermediates and side products by the application of carbon-13 nmr spectroscopy to the reaction as it progressed using carbon-13 labelled di ketones to enhance the detection of low level intermediates. It has been shown convincingly that some organic reactions proceed via a small number of irreversible processes amongst a very complex set of more rapid equilibrium processes.

The chemistry of rhenium has received considerable interest due to its versatility in various catalytic applications, fixation and especially the potential use of 186Re and 188Re radionuclides in nuclear medicine. This study investigates the synthesis and characterisation of rhenium complexes with potentially multidentate ligands containing the amino, imino, hydroxyl and thiol groups. It reports new rhenium complexes in the +1, +3, +4 and +5 oxidation states, which display structural diversity, from monomers to ligand-bridged dimers as well as metal-metal multiply bonded dimers. The reaction of orotic acid (H2oa) and 2-mercapto-orotic acid (H2moa) with trans- [ReOX3(PPh3)2] (X = Cl, Br) were studied and led to the formation of ligand-bridged dimers with metal-metal multiple bonds i.e. (μ-Br)(μ-O)(μ-oa)[Re2 IVBr(OEt)2(PPh3)2], (μ-X)(μ-O)(μ-oa)[Re2 IVX2(OiPr)(PPh3)2] and (μ-Cl)(μ-O)(μ-moa)2[Re(PPh3)]2. The reaction of H2oa with [ReO2(py)4]Cl, [Re(dab)Br3(PPh3)2] (H2dab = 1,2- diaminobenzene) and [Re(CO)5Cl] were also studied and monomeric complexes [ReO(py)2(OEt)(oa)], [Re(dab)Br(oa)(PPh3)2] and (Ph4P)[Re(CO)3(H2O)(oa)] were isolated. The treatment of 5-amino-orotic acid (H2aoa) with [ReOBr3(PPh3)2] led to dimers with metal-metal triple bonds ReIV≡ReIV i.e. (μ-Br)(μ-O)(μ-oa)[Re2 IVBr(OEt)2(PPh3)2], (μ-Br)(μ-O)(μ-oa)[Re2 IVBr2(OiPr)(PPh3)2], as well as the monomer [ReV(apd)Br(aoa)(PPh3)2] (apd2− = 5-imidopyrimidine-2,4-dione). The chelating ligand 5-aminopyrimidine-2,4-dione (H2apd) was formed by oxorhenium(V)-catalysed decarboxylation of 5-amino-orotic acid (H2aoa) (see Scheme 1). The reaction of the Schiff base derivative of 5-amino-ortic acid, salicylimine-orotic acid (H2soa), with trans-[ReOI2(OEt)(PPh3)2] in ethanol was also investigated and led to the formation of the rhenium(III) complex salt [Re(coa)I(PPh3)2]I [Hcoa = 5-(2- hydroxybenzylideneamino)pyrimidine-2,4(1H,3H)-dione]. The chelating Hcoa is also formed from the oxorhenium(V)-catalysed decarboxylation of H2soa and coordinates to the rhenium(III) ion as a monoanionic tridentate N,O,O-donor chelate via the phenolate and ketonic oxygens, and the imino nitrogen atom. However, decarboxylation of H2soa was not observed in its reaction with [ReOCl3(PPh3)2], which led to the isolation of [ReOCl(soa)(PPh3)]. The reaction of the carboxamide derivative of 5-aminoorotic acid, 5-(5-aminopyrimidine-2,4(1H,3H)- dioxamido)-1,2,3,6-tetrahedro-2,6-dioxopyrimidine-4-carboxylic acid (H2ampa) with [Re(CO)5Cl] in ethanol led to the formation of a zwitterionic rhenium(I) complex [Re(CO)3(H2O)(amef)] [amef = {5-(5-ammoniumpyrimidine-2,4(1H,3H)-dioxamido)- 1,2,3,6-tetrahedro-2,6-dioxopyrimidine-4-ethylformate}]. The chelating ion amef was formed from the combined tricarbonylrhenium(I)-catalysed esterification and aminoprotonation of H2ampa (see Scheme 1) and coordinates to the fac-[Re(CO)3]+ core as a dianionic bidentate N,N-donor chelate via the amido nitrgens.

The reactions of butyl mercaptides with fluoro-, bromo-, nitro-, and methoxynaphthalenes in DMSO and methanol have been studied. The halonaphthalene reactions gave reasonably good yields of alkyl naphthyl sulfides via direct nucleophilic substitution. 1-Halonaphthalene gave only 1-substituted alkyl naphthyl sulfide and 2-halo- naphthalenes gave only 2-substituted alkyl naphthyl sulfides. No alkyl naphthyl sulfide was produced from either methoxynaphthalene or nitronaphthalene.