Item – Theses Canada

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OCLC number
57002869
Link(s) to full text
LAC copy
LAC copy
Author
Ikeda, Glenn Kazuo,1979-
Title
Kinetic isotope effects in the fragmentation of N1' -methyl-2-(1-hydroxybenzyl)thiamin.
Degree
M. Sc. -- University of Toronto, 2003
Publisher
Ottawa : National Library of Canada = Bibliothèque nationale du Canada, [2004]
Description
1 microfiche.
Notes
Includes bibliographical references.
Abstract
The N1'-methylated conjugate of thiamin and benzaldehyde, N1'-methyl-2-(1-hydroxybenzyl)thiamin (MHBzT) decomposes in solution to yield trimethyl amino pyrimidine and phenyl thiazole ketone. The mechanism of this fragmentation is hypothesized to involve reversible proton removal from carbon, prior to a subsequent step involving cleavage of the C-N bond linking the two heterocycles. A buffer dependence study revealed that at low buffer concentrations, proton transfer is rate-determining, while at high buffer concentrations, reprotonation competes with the subsequent fragmentation step. Fragmentation was found to be very fast and surprisingly competitive with the kinetically significant rate of protonation. A buffer dependent primary kinetic isotope effect was measured for MHBzT-C2[alpha] (H/D), which demonstrated significant variation due to differing contributions from the hydroxide and buffer-catalyzed proton removal steps. An inverse solvent isotope effect was also measured and is characteristic of reversible protonation of carbon.
ISBN
0612841502
9780612841505