Dimeric ß-Ether Thioacidolysis Products Resulting from Incomplete Ether Cleavage

Four β-ether dimers which result from incomplete β-ether cleavage of syringyl-guaiacyl lignins following non-optimized thioacidolysis/desulfurization of plant materials were identified. The compounds were ; the guaiacyl-guaiacyl dimer 3-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxy-4-propylphenoxy)propan-1-ol, the guaiacyl-syringyl dimer 2-(2,6-dimethoxy-4-propylphenoxy)-3-(4-hydroxy-3-methoxyphenyl)-propan-1-ol, the syringyl-guaiacyl dimer 3-(3,5-dimethoxy-4-hydroxyphenyl)-2-(2-methoxy-4-propylphenoxy)-propan-1-ol, and the syringyl-syringyl dimer 3-(3,5-dimethoxy-4-hydroxyphenyl)-2-(2,6-dimethoxy-4-propylphenoxy)-propan-1-ol. Synthesis of each dimer, by extending dimeric lignin model β-ether strategies, provided authentication of the structures.