Caracteristiques photochimiques de quelques cetones polycycliques: Reactivite du cetene intermediaire

The photoreaction of some polycyclic ketones, derived from natural sesquiterpenic hydrocarbons, involves the formation of the ketene intermediate. This ketene can either add to protic solvents such as alcohols to give the corresponding esters, or decarbonylate in aprotic solvents. This decarbonylation of the ketene occurs only if its vibrational energy reaches a sufficient level, and leads to a carbene with a good yield. In comparison with aprotic solvents, the quantum yield of photoreactivity is increased when alcohol is present, while the quantum yield of phosphorescence is lower.