| dc.contributor.author | Thangarasa, Rasiah. | en_US |
| dc.date.accessioned | 2014-10-21T12:38:27Z | |
| dc.date.available | 1990 | |
| dc.date.issued | 1990 | en_US |
| dc.identifier.other | AAINN64368 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/55164 | |
| dc.description | The $\sp{119}$Sn and $\sp $C nmr spectra of solutions of 2,2-di-n-butyl-1,3,2-dioxastannolane (1) and a number of its symmetrical derivatives in non-polar solvents have been studied as functions of temperature and concentration. The species present for solutions of 1 and of related derivatives of disecondary diols have been identified as dimers, trimers, tetramers and pentamers. The compositions of the mixtures of oligomers were found to be approximately the same for all of these compounds at the same temperature and concentration. In contrast to earlier work, no evidence for the presence of monomers was obtained. Thermodynamic parameters for equilibration of the oligomers of 1 and another compound were calculated. The compositions of the oligomeric mixtures are extremely temperature dependent because of the large entropy terms. A derivative of a ditertiary diol, 2,2-di-n-butyl-4,4,5,5-tetramethyl-1,3,2-dioxastannolane exists in non-polar solvents predominantly as a dimer over the temperature range studied, from $-$60 to +80$\sp\circ$C. It undergoes exchange with a very small amount of monomer present in the solution. | en_US |
| dc.description | A number of di-n-butylstannylene acetals derived from carbohydrates have been studied in solution by $\sp1$H, $\sp $C and $\sp{119}$Sn nmr spectroscopy. The oligomeric species present in solutions of these compounds have been identified. The particular oligomer or oligomers present has been found to be mainly determined by the orientations of the substituents on carbons in the pyranose ring adjacent to those in the stannylene ring. The regiochemistry of reactions of stannylene acetals was related to the species present in solution. The species present in solutions of stannylene acetals containing N-methylimidazole (NMI) were identified as dimer, dimer-NMI and monomer-NMI adducts. Evidence was presented as to which of the NMI adducts is responsible for the marked increase in reaction rate and the change in regioselectivity sometimes observed in the presence of nucleophiles. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 1990. | 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 | Oligomerization equilibria of 1,3,2-dioxastannolane derivatives of simple diols and carbohydrates, the effects of addition of nucleophiles and their selective reactions. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
