Degree Type

Dissertation

Date of Award

1982

Degree Name

Doctor of Philosophy

Department

Chemistry

Abstract

Cothermolysis of hexamethylsilacyclopropane and cyclooctene oxide afforded cyclooctene in moderate yields. Inclusion of D(,3) in the reaction, as a silanone trap, afforded cyclooctene and D(,4) in moderate yields. Cophotolysis of dodecamethylhexasilacyclohexane and cyclooctene oxide also afforded cyclooctene, the yield of which was inversely proportional to the length of time of photolysis. Inclusion of D(,3) in the photolysis reactions also afforded D(,4) in good yields along with small amounts of D(,5). The amount of silanone trapping was found to be independent of the length of time of photolysis. These reactions were proposed to proceed by initial formation of a silyl-ylid which decomposed in a bimolecular fashion to afford the observed products;The intramolecular chemistry of a number of substituted methylsilylenes was examined. Methyl(trimethylsilyl)methylsilylene gave 1,1,3-trimethyl-1,3-disilacyclobutane in good yield. Vinyl-methyl- and (beta)-styrylmethylsilylene afforded methylsilylacetylene and 1-methyl-1-silaindene, respectively, in moderate yields. In contrast, cyclopentadienylmethylsilylene failed to afford identifiable products;Addition of dimethyl acetylenedicarboxylate to 1,1-dimethyl-2,5-diphenylsilole afforded 1,2-dicarbomethoxy-3,6-diphenyl-7,7-dimethyl-7-silanorbornadiene in good yield in CCl(,4) in the absence of O(,2). In the presence of O(,2) or upon heating in the absence of O(,2) this compound rearranged by a 1,5-silyl migration from carbon to oxygen to afford a bicyclo-O-silyl-O-alkylketenacetal. This isomerization was found to be general for 7-silanorbornadienes containing a carbonyl functionality at the one position. In addition, the previously reported chemistry of a number of 7-silanorbornadienes was clarified and corrected;The synthesis and chemistry of a number of alkenyl-substituted silyl radicals were examined. Flash-vacuum-pyrolysis of allyl-, 3-butenyl, and 4-pentenyldimethylsilane afforded the same products, which were proposed to arise by a series of nonselective bond homolysis reactions followed by bimolecular coupling reactions. Generation of alkenyl-substituted silyl radicals by hydrogen abstraction or mercury-sensitized photolysis of the corresponding silyl hydrides afforded oligomers rather than compounds derived by intramolecular cyclization.

DOI

https://doi.org/10.31274/rtd-180813-7953

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

William F. Goure

Language

en

Proquest ID

AAI8307747

File Format

application/pdf

File Size

408 pages

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