Abstract
Irradiation of tert-butyl 9-anthroate and furan through a Uranium glass filter gave the [4+4] cyclodimer (21.8%) of tert-butyl 9-anthroate and furan and the 1,4-10',9' cyclodimer (4.2%) of tert-butyl 9-anthroate as well as the 9,10-10',9' cyclodimer (65.7%) of tert-butyl 9-anthroate. The [4+4] cyclodimer of tert-butyl 9-anthroate and furan was found to be thermally dissociated into their unit components with the activation enthalpy of 35.6 kcal/mole and the activation entropy of 7.6 eu, and photochemically dissociated to produce excited tert-butyl 9-anthroate. Quantum yields for the photodissociation to tert-butyl 9-anthroate and the formation of excited tert-butyl 9-anthroate in cyclohexane at room temperature were determined to be 0.56 and 0.19, respectively. The 1,4-10',9' cyclodimer of tert-butyl 9-anthroate in DMF was thermally dissociated into tert-butyl 9-anthroate with the activation enthalpy of 34.8 kcal/mole and the activation entropy of 16.4 eu. Upon irradiation, the [4+4] cyclodimers of tert-butyl 9-anthroate and the [4+4] cyclodimers of methyl 9-anthroate were quantitatively dissociated. However, no adiabatic photoreversion was observed from any of the cyclodimers. Quantum yields for the photodissociation in cyclohexane at room temperature were measured and compared.