The direct cleavage of the CC bond into lignin bonds is a promising route to the production of high quality aromatics, but it is usually related to metal-based catalysts and harsh conditions. A photothermal strategy is reported here to deconstruct the Cα-Cβ bond in lignin β-O-4 and β-1 linkages in ionic liquid [BMim] [NTf2] . It was found that the synergism of UV light and heating could trigger the Norrish Type I reaction by inducing the cleavage of the Cα-Cβ bond and provide aromatic aldehydes via free radicals in modest yields. In the meantime it is [BMim] [NTf2] could interact with lignin units and stabilize the intermediates that contribute significantly to Cα-OH protonation and accelerate the breakdown of lignin bonds between the units. In this unique way, the Cα-Cβ bond could be cleaved at 50 ° C and UV irradiation without metal. A further comparison with photochemical or thermochemical sole strategies shows that the photothermal route offers a significant improvement in reactivity for cleavage of the Cα-Cβ bond. Alkali lignin could also be broken down into aromatic monomers [BMim] [NTf2] using the protocol. Given the need for biomass upgrading, this work could provide a green and unique technology to enhance inert C — C bond cleavage in photothermal synergism under metal-free and mild conditions that could support future advances in photothermal transformation and renewable energy generation.

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