Pogr
The Final Oral Examination
for the Degree of
DOCTOR OF PHILOSOPHY
(academic unit)
Student name
2000
1997
UBC
McGill University
M.Sc.
Hons. B.Sc.
“title of dissertation”
May 12th, 2008
2:00 pm
David F. Strong building, room C114
Supervisory Committee:
Dr. Peter C. Wan, Department of Chemistry, UVic
(Supervisor)
Dr. Alexander G. Briggs, Department of Chemistry, UVic
Dr. Reginald H. Mitchell, Department of Chemistry, UVic
Dr. Richard Keeler Department of Physics and Astronomy,
UVic (Outside Member)
External Examiner:
Dr. Mark S. Workentin, Department of Chemistry,
University of Western Ontario
Chair of Oral Examination:
TO BE COMPLETED BY FGS, Department of English, UVic
Abstract
The discovery and mechanistic investigation of a
new class of photochemical reactions of benzophenones
and related compounds is documented in this Thesis.
Their photobehaviour in aqueous solvent media varied
dramatically from their well-known behaviour in organic
solvents and suggests unique and unprecedented
mechanistic pathways.
The aqueous photoredox
chemistry of various substituted benzophenones was
initially explored. Particular attention was paid to 3(hydroxymethyl)benzophenone, which upon photolysis in
acidic aqueous media undergoes an intramolecular
photoredox reaction to produce 3-formylbenzhydrol.
Extensive investigation into the mechanistic behaviour of
3-(hydroxymethyl)benzophenone produced evidence of a
unique solvent mediated, acid catalysed photoreaction. A
mechanism has been proposed for the intramolecular
photoredox reaction that proceeds via the protonated
triplet state. This protonated triplet state subsequently
promotes the deprotonation of the benzylic carbon before
rearranging to form the redox product. The modification
of the benzylic carbon with an alkyl group or with a
phenyl group resulted in only slight changes in the
photobehaviour. In both cases intramolecular photoredox
reactions were observed although significantly more
oligomeric side products were observed in some cases.
To more fully elucidate photobehaviour and to test
the generality of the photoredox reaction, a variety of
different, structurally related hydroxyalkyl aromatic
carbonyls were synthesized and studied.
Alternative
chromophores were explored using xanthone and
fluorenone derivatives.
Both derivative compounds
underwent
intramolecular
photoredox
reaction,
supporting the assertion that the intramolecular
photoredox reaction could be considered a general
feature of aromatic carbonyls under aqueous conditions.
However, significant differences in photoreactivity were
also
observed.
It
was
found
that
2(hydroxymethyl)xanthone
exhibited
sufficient
photoactivity that the intramolecular photoredox reaction
was observable even under neutral conditions whereas 2(hydroxymethyl)fluorenone was nearly photoinert.
The last topic focuses on the extension of the
electronic transmission from the carbonyl functional group
to the benzylic alcohol by insertion of an additional phenyl
group. The addition of the phenyl group also provided a
bichromophoric
molecule,
rather
than
the
monochromophoric substrates studied to this point. The
substituent’s position played an important role in the
photobehaviour, in that both of the meta- and orthosubstituted
compounds
underwent
intramolecular
photoredox reaction, while the para- substituted
compound primarily exhibited photobehaviour indicative
of hydrogen abstraction.
Awards, Scholarships, Fellowships
2002
1993-1997
1993-1997
Dr. E. and Mrs. M. von Rudloff Scholarship
J.W. McConnell Entrance Scholarship
Canada Scholarship for Science and
Engineering
Presentations
1. Mitchell, D. and Wan, P. “Intramolecular Photoredox
Chemistry induced by Anthraquinone through the
Biphenyl Ring Systems” 85th Conference of the
Canada Society for Chemistry, Vancouver, British
Columbia, Canada. June 2002 (poster)
2. Mitchell, D; Lukeman, M. and Wan, P. “Intramolecular
Photoredox Chemistry of Substituted Benzophenones –
A New Class of Reaction for Aromatic Ketones.” 86th
Conference of the Canada Society for Chemistry,
Ottawa, Ontario, Canada., Aug. 2003.(oral)
3. Mitchell, D.; Basaric, N.; and Wan, P. “Intramolecular
Photoredox Chemistry of Substituted Benzophenonesthe Effect of Phenyl Substituents.” 89th Conference of
the Canada Society for Chemistry, Halifax, Nova
Scotia, Canada. May. 2006.(oral)
Publications
1. Storr, T.;* Mitchell, D.; Buglyó, P.; Thompson, K.H.;
Yuen, V.; McNeill, J.H. and Orvig, C. *“VanadylThiazolidinedione Combination Agents for Diabetes
Therapy.” Bioconjugate Chemistry 2003, 14 (1), 212 221.
2. Mitchell, D.*; Lukeman, M.; Lehnherr, D. and Wan, P.
*“ Formal Intramolecular Photoredox Chemistry of
Meta-Substituted Benzophenones” Organic Letters,
2005, 7(15), 3387 – 3389
3. Basaric, N.; Mitchell, D.; Wan, P. “Substituent effects
in the intramolecular photoredox reactions of
Benosphenones in aqueous solution.” Canadian
Journal of Chemistry, 2007, 85, 561 - 571