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On the conformational analysis and photochemical reactivity of 1,6-cyclodecanedione

TitleOn the conformational analysis and photochemical reactivity of 1,6-cyclodecanedione
Publication TypeJournal Article
Year of Publication1996
AuthorsLewis, TJ, Rettig, SJ, Sauers, RR, Scheffer, JR, Trotter, J, Wu, CH
JournalMolecular Crystals and Liquid Crystals Science and Technology Section a-Molecular Crystals and Liquid Crystals
Volume276
PaginationA289-A298
Type of ArticleProceedings Paper
ISBN Number1058-725X
KeywordsABSTRACTION, C-H...O, II REACTIONS, KETONES, MOLECULAR MECHANICS METHODOLOGY
Abstract

Photolysis of 1,5-cyclodecanedione, both in the crystalline state and in solution, fails to lead to any Norrish/Yang type II products despite the fact that the conformation of the molecule in the solid state is nearly ideal for hydrogen atom abstraction. Based on X-ray crystal structure and molecular modeling studies, it is argued that gamma-hydrogen abstraction does occur in the solid state, but that closure of the resulting 1,4-biradical is slower than reverse hydrogen atom transfer owing to difficulty in forming the expected 8-membered ring-containing photoproduct. In solution, on the other hand, molecular mechanics calculations indicate that the lack of photoreactivity of 1,5-cyclodecanedione stems from the fact that this molecule exists nearly exclusively in a conformation for which gamma-hydrogen abstraction is sterically impossible.

URL<Go to ISI>://A1996UJ43200083