Abstract
Though the phase-separation system composed of the concentrated acid and p-alkylphenols, the lignin-based polymers (lignophenols) with the switching devices for the functionality control were synthesized. p-Substituted phenols grafted to C1 of the lignin side chain attacked C2 in alkaline media, followed by the cleavage of 2-O-aryl ether and the exchange of phenolic functionality from C1 phenols to lignin nuclei. Using 2, 6-dimethylphenol (the control device), the switching functions of various ligno-p-alkylphenols were controlled. There was a good correlation between the frequency of phenolic nuclei with C2-attackable OH and the depolymerization degree. Furthermore, compared with ligno-2, 4-dimethylphenol, the rate of alkaline depolymerization of ligno-p-n-propylphenol was lower, indicating that the switching functions of C1-grafted p-alkylphenols were affected to a larger extent by their steric factors rather than their electronegativity.
