Laser Techniques in the Study of the Photochemistry of Carbonyl Compounds Containing Ligninlike Moieties

The photochemistry and photophysics of some lignin-related compounds has been studied. The triplet state of these compounds is relatively low at 60 kcal/mol, and is π-π* in nature. The π-π* nature is due to methoxy substitution on the chromophore and results in relatively long triplet lifetimes and low reactivity, compared to n-π* triplets like that of benzophenone. The α-phenoxy group of α-guaiacoxyacetoveratrone provides this lignin model compound with a β-phenyl ring for triplet deactivation as well as a source of a phenoxy radical after cleavage. The intersystem crossing quantum yield is significantly less than unity which is consistent with evidence for cleavage from the singlet state.