Multi-step degradation method for β-O-4 linkages in lignins: α-TSA method. Part 1: Reaction of non-phenolic dimeric β-O-4 model compound

The α-TSA method has been developed for the cleavage of β-O-4 linkages in lignin. It consists of three steps: (1) thioetherification at α-position of β-O-4 substructures, (2) sulfonylation, and (3) mild alkali treatment of the α-sulfone derivative. The method was tested on a nonphenolic dimeric β-O-4 lignin model compound, namely on 4-benzyloxy-3-methoxyphenylglycerol-β-guaiacyl ether. It demonstrated that the mild alkali degradation of the α-sulfone derivative proceeds efficiently, i.e., the electron-withdrawing sulfone group at α-position contributes to the cleavage of the β-O-4 linkage in the same mechanism as that in the γ-TTSA method.