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Crystallographic studies related to the solid state photochemistry of [alpha]-cycloalkylacetophenones Evans, Stephen Vincent Ashley
Abstract
The crystal and molecular structures of fifteen α-cycloalkylacetophenones and propiophenones have been determined with the use of X-ray crystallography. All of the compounds are known to undergo the Norrish type II reaction in the solid state, which involves abstraction of a favourably oriented Ƴ-hydrogen atom to yield a biradical which can undergo either cleavage or cyclization. The compounds were studied to examine the effect of variation in aromatic ring substituents and cycloalkyl ring size on the nature and surroundings of the reaction site, and, if possible, to develop structure-reactivity relationships for reactions in the solid state. Almost all of the acetophenone derivatives with simple cycloalkyl rings studied assume a common conformation in the solid state, with the acetophenone moiety occupying an equatorial position on the cycloalkyl ring, and with the Ƴ-hydrogen atom most likely to be abstracted utilizing a boatlike abstraction geometry. The effect of α-methyl substitution of the α-cycloalkylacetophenones (to produce the corresponding propiophenones) is to rotate the cycloalkyl moiety by approximately 100° about the acyl-carbon α-carbon bond. The conformations of the cycloalkyl rings are in accord with those expected. The cycloheptyl rings assume twist-chairs (though somewhat disordered), while the cyclooctyl ring all display boat-chair conformations. Four α-adamantylacetophenones assume similar conformations in the solid state (with chair like abstraction geometries), but small differences in conformation were found to account for large differences in photochemical behaviour. Structural studies of a 3-methyladamantyl derivative yielded information as to the preferred pathways for cyclobutanol formation in the solid state, and provided an opportunity for producing an optically active product mixture from an achiral starting.
Item Metadata
Title |
Crystallographic studies related to the solid state photochemistry of [alpha]-cycloalkylacetophenones
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1986
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Description |
The crystal and molecular structures of fifteen α-cycloalkylacetophenones
and propiophenones have been determined
with the use of X-ray crystallography. All of the compounds
are known to undergo the Norrish type II reaction in the solid
state, which involves abstraction of a favourably oriented
Ƴ-hydrogen atom to yield a biradical which can undergo either
cleavage or cyclization. The compounds were studied to examine
the effect of variation in aromatic ring substituents and
cycloalkyl ring size on the nature and surroundings of the reaction
site, and, if possible, to develop structure-reactivity
relationships for reactions in the solid state.
Almost all of the acetophenone derivatives with simple
cycloalkyl rings studied assume a common conformation in the
solid state, with the acetophenone moiety occupying an
equatorial position on the cycloalkyl ring, and with the
Ƴ-hydrogen atom most likely to be abstracted utilizing a
boatlike abstraction geometry.
The effect of α-methyl substitution of the α-cycloalkylacetophenones
(to produce the corresponding propiophenones) is
to rotate the cycloalkyl moiety by approximately 100° about
the acyl-carbon α-carbon bond. The conformations of the cycloalkyl rings are in accord
with those expected. The cycloheptyl rings assume
twist-chairs (though somewhat disordered), while the cyclooctyl ring all display boat-chair conformations.
Four α-adamantylacetophenones assume similar conformations
in the solid state (with chair like abstraction
geometries), but small differences in conformation were found
to account for large differences in photochemical behaviour.
Structural studies of a 3-methyladamantyl derivative yielded
information as to the preferred pathways for cyclobutanol
formation in the solid state, and provided an opportunity for
producing an optically active product mixture from an achiral
starting.
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Genre | |
Type | |
Language |
eng
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Date Available |
2012-03-09
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0062313
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.