Degree Type

Dissertation

Date of Award

1986

Degree Name

Doctor of Philosophy

Department

Chemistry

Abstract

Exploratory and mechanistic photochemistry of tetraphenyl-, triphenyl-, diphenyl- and phenyl-allene are described in alcohol and hydrocarbon solvents. Phenylallene singlet excited states yield predominantly allylic methyl ethers in methanol. A high stereoselectivity and deuterium isotope effect observed for product formation strongly argue for a rate determining protonation and fast methoxide trapping in an effectively concerted manner. By contrast, phenylallenes undergo photoisomerization to cyclopropenes, indenes and propynes in hydrocarbon solvents. The common, but not exclusive, intermediacy of vinyl-carbenes in allene and cyclopropene photochemistry is strongly indicated by product studies, independent generation and deuterium isotope effects. Reactions of photogenerated radical cations of tetraphenyl- and triphenyl-allene and triphenylpropyne in methanol are described. Allene radical cations yield vinyl methyl ethers as the major products whereas the predominant pathway for the propyne radical cations is efficient deprotonation-reprotonation to allene.

DOI

https://doi.org/10.31274/rtd-180813-5734

Publisher

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

Copyright Owner

Michael W. Klett

Language

en

Proquest ID

AAI8615059

File Format

application/pdf

File Size

201 pages

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