Visible-Light-Induced Selective C–C Bond Cleavage Reactions of Dimeric β‑O‑4 and β‑1 Lignin Model Substrates Utilizing Amine-Functionalized Fullerene

Finding a selective and efficient
fragmentation process under ambient
conditions is pivotal for the generation of fuels and chemical feedstocks
from lignoceullosic biomass. In the present study, visible-light and
amine-functionalized fullerene-based photocatalyst-promoted photodegradation
reactions of dimeric β-O-4 and β-1 lignin model compounds,
containing varying numbers of methoxy substituents on the arene ring,
were explored to find and develop mild, eco-friendly photochemical
techniques for efficient delignification. The results showed that,
in contrast to well-known organic photoredox catalysts, amine-functionalized
fullerene photocatalyst promoted photochemical reactions of lignin
model compounds could lead to more efficient lignin fragmentation
reactions through a pathway involving a selective Cα–Cβ bond cleavage process, and in addition,
Cα-hydroxyl moiety in lignin model compounds played
a significant role in the success of the Cα–Cβ bond cleavage reaction of lignin model substrates.