PHOTOCHEMICAL REACTIONS OF CARBONYL COMPOUNDS IN SOLUTION .2. PATERNO-BUCHI REACTION AND ENERGY TRANSFER

Abstract— Photosensitization with sensitizers of various triplet energy levels was applied to the addition of 9‐anthraldehyde to 2,3‐dimethyl‐2‐butene in order to determine the nature of two reactive excited states of 9‐anthraldehyde. The results indicate that they are most likely an upper triplet state (T2) and a singlet excited state of 9‐anthraldenyde. In a separate series of experiments, it was demonstrated that Paterno‐Büchi reactions occur concurrently with energy transfers from the triplet state of carbonyl compounds to simple olefins in high efficiency. The triplet state of simple olefins is likely to have a nonplanar configuration after the energy transfer. The possible mechanisms of such transfers are discussed. La fotosensitivación con sentivizadores con varios niveles de energia en el estado triplete fué aplicado a la adición de 9‐antraldehido a 2,3 dimetil‐2‐buteno, con el objeto de deteminar la naturaleza de los estados excitados reactivos del 9‐antraldehido. Los resultados indican que son un estado triplete superior (T2) y un estado singulete del 9‐antraldehido. En una serie separada de experimentos se ha demonstrado que las reacciones de Paterno‐Büchi ocurren con transferencias de energía del estado triplete de compuestos carbonílicos a olefinas simples con eflciencia alta. El estado triplete de olefinas simples parece tener una configuración no planar después de la transferencia de energía. Se discuten los mecanismos posibles de esas transferencias. Copyright © 1968, Wiley Blackwell. All rights reserved