Photoreaction of Phenacyl Aryl Ether Type Lignols

Photoreactions of two dilignols, a trilignol and two tetralignols, all of which contain a phenacyl aryl ether type structure, were investigated. All lignols in ethanol yielded products showing the homolytic cleavage of a phenacyl aryl ether bond in this structure. As to tetralignols photodiscoloration was hardly observed in the absence of air, and the preexistence of a free phenolic hydroxyl groups showed no influence on discoloration even in the presence of air. Photoreaction on a filter paper revealed that main reactions are the recombination of radicals once formed by irradiation and the reaction of radicals with oxygen.