Valerophenone triplet quenching

Figure 5.35. Comparison of the theoretical and the observed relation between and I/r for triplet quenching of valerophenone by 2,S-dimethyl-2,4-hexa-diene (adapted from Wagner and Kochevar, 1968).

This latter equation correctly predicts the rates at which 1-iodo-naphthalene quenches triplet naphthalene in several fairly viscous solvents.165 It also correctly predicts the rate at which 2,5-dimethyl-2,4-hexadiene quenches triplet valerophenone in cyclooctane if the ketone s triplet lifetime is the same as that estimated from quenching experiments and from the flash spectroscopically measured rate constant for diffusion-controlled quenching in benzene.183... 

A very early example is provided by the study of solvent viscosity effects on the rate constants for bimolecular quenching of triplet valerophenone by dienes. Several studies by the Wagner group on the competing type II reactions of a,co-diacylaIkanes have provided measures of the rates of internal triplet energy transfer between the two carbonyl groups. 

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