Anthracenes in Direct Photooxygenation Reactions

The type II direct photooxygenation of anthracene and its derivatives has been studied quantitatively by Bowen,2 Livingston,3 and their co-workers. Quantum yields of fluorescence, dimerizations, and 

As in the former cases, k2 was calculated from the integrated extinction coefficients,149 k3 + kt was derived from fluorescence quantum yields,149 while k3 and k4 were separately estimated from the maximum quantum yields of photooxygenations at high oxygen concentrations.150 Flash spectroscopy techniques were used in order to determine k5 and k7, while kB was obtained from the Stern-Volmer quenching constant of oxygen.149 The ratio ke/kg was determined from the variation of / AOz with the concentration of the anthracene.71 When photodimerization occurred, k13l(kia + k13) was calculated from the maximum yield of 

Dimerization was unequivocally shown to occur for anthracene in benzene and bromobenzene even in the presence of oxygen.71 The quantum yields of dimerization, f Az, as a function of concentrations of anthracene, A, and of oxygen follows 

Carbon disulfide quenches the fluorescence of anthracene quite efficiently,145,149 but seems to have little effect on its triplet lifetime.147 Diphenylanthracene in benzene fluoresces with a quantum yield of 0.8 and shows a high sensitivity to the oxygen concentration in photooxygenation reactions. With about 1 vol% of CS2 present, f AC 2 is practically independent of [02] ( 10 5 mole/liter). In jjoth cases, where carbon disulfide was either used as solvent or was added to an otherwise strongly fluorescent solution, the quantum yields of photooxygenation followed 

Spectroscopic Data, Quantum Yields, and Rate Constants Anthracenes in Different Solvents at Room Temperature (from refs. 71 and 146) 

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