STUDY OF PHOTOCHEMICAL-REACTIONS OF CONIFERYL ALCOHOL .1. MECHANISM AND INTERMEDIATE PRODUCTS OF UV RADIATION-INDUCED POLYMERIZATION OF CONIFERYL ALCOHOL

Ultraviolet light-induced photochemical transformations of coniferyl a lcohol have been studied, using spectrophotometric and H-1 NMR approac hes. It was shown earlier that coniferyl alcohol can be polymerized no t only enzymically but also by photoirradiation, This study furthers o ur knowledge on the UV radiation-induced polymerization of coniferyl a lcohol. In the photochemical reaction of coniferyl alcohol, quinone-me thide is the first transient formed. In subsequent reactions quinone-m ethide produces dimers, oligomers and a polymer as the end product. Th e reaction rate constants are pH dependent. The results are interprete d in terms of an ionic mechanism of the photochemical reaction, contra ry to enzymic polymerization that involves formation of phenoxy radica ls. The study may have ecological importance because of the increase o f UV radiation reaching the earth's surface due to ozone layer depleti on.