Zur Photochemie von Δ1,9-10-Methyl-2-octalon

Some aspects of the photochemistry of Δ^1,9-10-methyl-2-octalone ( 1 ) were reinvestigated. In view of the hitherto neglected substantial thermal reversibility of the photolytic double bond shift under previous conditions of analysis (1) the solvent-dependent selectivity in product formation in C₆H₆ and t-BuOH was confirmed, (2) the essentially exclusive double bond shift and its intermolecular nature in C₆F₆ were established, (3) the quantum yields of the major products in these three solvents were measured, and (4) the dependence of triplet quenching data on temperature, enone concentration and conversion was shown in C₆F₆ for the double bond shift. In conclusion, the previously published experimental basis for the postulate of two differentially reactive triplet states of 1 is insufficient, although the postulate itself is not necessarily disproved.