dc.contributor.author Rockwell, Glen Donald. en_US dc.date.accessioned 2014-10-21T12:36:30Z dc.date.available 2014-10-21T12:36:30Z dc.date.issued 1997 en_US dc.identifier.other AAINQ24761 en_US dc.identifier.uri http://hdl.handle.net/10222/55501 dc.description The positions of the equilibria between the diaxial and diequatorial conformers of $\sp$C-labelled trans-1,2-dimethoxycyclohexane (2) and trans-2-methoxycyclohexanol (9) were measured accurately using $\sp$C NMR at 193 K in a variety of solvents ranging in polarity from pentane to methanol. The population of the diequatorial conformer was observed to increase as solvent polarity increased. Improved parameters for the OCCO torsional term in the MM3(94) force field have been developed that fit experimental observations for a variety of ethers much better than the original values. The $\sp1$H NMR spectrum of 1,2-dimethoxypropane (5) in cyclohexane-$d\sb$ was analysed and the composition of its conformational mixture was determined. The previous gas phase results for this compound have been shown to be inaccurate and have been reinterpreted. en_US dc.description Methyl 2,3,4,6-tetra-O-$\rm \lbrack \sp2H\sb3\rbrack$methyl-$\alpha$- scD-glucopyranoside (6a), its 4-$\sp$C-labelled analog and methyl 2,3,-tri-O-$\rm \lbrack\sp2 H\sb3\rbrack$methyl-$\alpha$- scD-glucopyranoside (18) were synthesized. The C5-C6 rotameric compositions for these compounds were determined in a range of solvents from the $\sp3J\sb{\rm H5,H6R}$ and $\sp3J\sb{H5,H6S}$ values obtained from their 500 and 600 MHz $\sp1$H NMR spectra. Unambiguous assignments of the H6R and H6S signals were made from the 4-$\sp$C-labelled compound. The results showed that solvent had no significant effect on rotameric population unless OH-6 was available to form intramolecular hydrogen bonds. en_US dc.description Conformational analyses of tri-, tetra-, and pentathiacycloalkanes ranging in ring size from nine to sixteen membered were performed. The torsional terms in MM3(94) for CSCC, SCCC, and SCCS terms were improved and used in stochastic searches. For 1,4,7-trithiacyclononane (23), experimental results showed that the C$\sb3$ conformer (present in the solid phase) was not the dominant conformer in solution. Instead, a mixture of conformers was present. By contrast, 1,5,9-trithiacyclododecane (25) was found to adopt the same conformation in solution and in the solid phase. The calculations predict that at least two other macrocyclic thioethers would be good complex formers. The calculations successfully predicted the conformational stability of the D$\sb4$ conformer of 1,4,7,10-tetetrathiacyclododecane (26). Thermal analyses of six macrocyclic thioethers were also performed using differential scanning calorimetry. en_US dc.description Thesis (Ph.D.)--Dalhousie University (Canada), 1997. en_US dc.language eng en_US dc.publisher Dalhousie University en_US dc.publisher en_US dc.subject Chemistry, Organic. en_US dc.title Experimental and molecular mechanics studies of the conformations of compounds containing oxygen and sulfur. en_US dc.type text en_US dc.contributor.degree Ph.D. en_US
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