Conformational Analysis: A Forcefield for Ketones and Aldehydes

Flitman, Howard Philip (1978) Conformational Analysis: A Forcefield for Ketones and Aldehydes. MSc(R) thesis, University of Glasgow.

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Abstract

A force-field currently in use for application to alkanes and alkenes is extended, herein, so as to include a ketone/aldehyde capability. This is done by the inclusion of further constants to take into account terms due to 13 interactions involving the carbonyl group. The force-field is parameterized so as to reproduce as closely as possible the geometries of 27 carbonyl compounds possessing widely differing structural features and also the standard heats of formation of 39 ketones and 10 aldehydes, these being all the carbonyl compounds for which appropriate data are available to date. The actual precise degree of correspondence obtained between the calculated and experimental data is not so high as in the case of the parent hydrocarbon force-field but vies favourably in comparison with the other principal carbonyl force-field in existence. An analysis follows of the geometrical and thermochemical results of carbonyl compounds for which the appropriate experimental data are as yet unavailable, so precluding comparisons. Miscellaneous applications include analyses of the conformers of ring-ketones and their relative energies and a survey of the compounds of (3.3.1) bicyclic structural types. Calculations find the chair-boat conformer of 1-methyl-7-exo-t-butyl(3.3.1)-bicyclononane-2,9-dione to be more stable than the twin-chair form, in agreement with observation. Similarly, 9-thia(3.3.1)-bicyclononane-2,6-dione is calculated to be slightly skewed, to relieve unfavourable non-bonded interactions, as is found experimentally, and two other sulphur-containing systems, 3-Oxa-7,9-dithia- and 9-oxa-3,7-dithia(3.3.1)bicyclononane are conformationally analyzed. For these cases, a further extension of the force-field so as to incorporate sulphide and ether parameters is described.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Keywords: Organic chemistry
Date of Award: 1978
Depositing User: Enlighten Team
Unique ID: glathesis:1978-78805
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2020 14:52
Last Modified: 30 Jan 2020 14:52
URI: http://theses.gla.ac.uk/id/eprint/78805

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