Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)




Dr. William J. Leigh


The direct solution photochemistry of 1,3,3-trimethylcyclopropene and 1-t-butyl-3,3-dimethylcyclopropene has been investigated. Primary photoproducts consisting of alkynes, allenes, and 1,3-dienes are formed from vinylcarbene intermediates, a result of cleavage of the C₁ - C₃ or C₂ - C₃ bond. Cleavage of the more substituted (C₁ - C₃) bond to yield a vinylcarbenes can account for > 80% of observed products. Most of the products are formed via 1,2- and 1,4-hydrogen migrations from the intermediate vinylcarbenes.

Photolysis of 1,3,3-trimethylcyclopropene-1-¹³C supports the intermediacy of vinylcarbenes in product formation from singlet excited cyclopropenes. In addition, evidence which strongly suggests the importance of a second pathway for formation of alkyne products from alkylcyclopropenes has been obtained. This pathway involves the intermediacy of vinylidene, formed by 1,2-hydrogen migration/ring opening (sequential or concened) from the singlet excited-state of cyclopropene.

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