Synthesis of Lignin‐Derived Bisphenols Catalyzed by Lignosulfonic Acid in Water for Polycarbonate Synthesis

Abstract Lignosulfonic acid, a byproduct of the paper industry, was demonstrated to be an efficient and green catalyst in water for the stoichiometric condensation of creosol with formaldehyde to synthesize lignin‐derived renewable bisphenols. The distribution and structures of the products were confirmed by 1 H NMR, 13 C NMR, and FTIR spectroscopy and X‐ray analysis; furthermore, a possible reaction mechanism was proposed. A polycarbonate was prepared from the bisphenol product and characterized as a model application, and thermogravimetric analysis (TGA) showed that decomposition occurred in a single stage with the maximum rate of degradation at approximately 420 °C. Differential scanning calorimetry (DSC) analysis showed that the glass transition temperature and melting peak of the polycarbonate were approximately 122 and 314 °C, respectively. The environmentally friendly characteristics of this study are featured by the integrated utilization of a biorenewable feedstock, a green biomacromolecule catalyst, and a green solvent for the preparation of valuable biochemicals and materials.