Date of Award


Document Type

Dissertation - Restricted

Degree Name

Doctor of Philosophy (PhD)



First Advisor

Mark G. Steinmetz

Second Advisor

Sheldon E. Cremer

Third Advisor

Kazuo Nakamoto

Fourth Advisor

Michael A. Mckinney

Fifth Advisor

Michael D. Ryan


The photochemistry of four-six membered ring vinylidenecycloalkanes and, additionally, the ground and excited state chemistry of a homologous series of spiro 2.n alk-1-enes (n = 3-5) were studied. The allenes were found to undergo excited state, 1,2-H migration on 185 nm photolysis to produce isomeric spirocyclopropenes ((PHI) = 0.016-0.034) and ethynylcycloalkanes ((PHI) = 0.011-0.019). Vinylmethylenes are discussed as potential intermediates. Isomeric 1-vinylcycloalkenes ((PHI) = 0.005) were also formed, presumably via carbene intermediates which undergo 1,4-H shifts. Depending on the structure of allene reactant, additional products were formed. For example photofragmentation of six and five-ring vinylidenecycloalkanes produced corresponding methylenecycloalkanes at short wavelength, 185 nm, but not at longer wavelength 228 nm. In the case of four and five-ring homologs, ring expansion to 3-methylenecycloalkenes was also important. Indication of the exocyclic allenic system and cyclobutane ring was significant for vinylidenecyclobutane, as evidenced by facile ((PHI) = 0.14) photochemical cleavage to ethylene and butatriene; in contrast pyrolysis produced 1,2-dimethylenecyclobutane. Comparison between ground and excited state chemistry of spirocyclopropenes revealed striking differences, photolysis at 185 nm led to isomerization to corresponding allenes ((PHI) = 0.10-0.15) and ethynylcycloalkanes ((PHI) = 0.07-0.17) for n = 3-5. For n = 4,5 1-vinylcycloalkenes were also photoproducts ((PHI) = 0.03). Photoextrusion of ethylene was the most efficient process ((PHI) = 0.46) of spiro 2.3 hex-1-ene, suggestive of spirocyclic interaction of cyclobutane ring and cyclopropene double bond. In contrast, pyrolysis of spirocyclopropenes (n = 3-4) gave high yields of ethynylcycloalkanes to the exclusion of isomeric allenes; 1-vinylcycloalkene was also formed for n = 4. Loss of ethylene was not observed in the ground state for spiro 2.n hex-1-ene.



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