Fully renewable diphenolic acid from levulinic acid, natural-based phenols and char-derived acid catalysts

Diphenolic acid is a promising alternative to bisphenol A for the production of epoxy resins and polycarbonates, due to their structural similarity, because the serious health and environmental concerns of the latter. Traditionally, diphenolic acid is synthesized through a condensation reaction between phenol and levulinic acid, carried out in the presence of an appropriate Brønsted acid catalyst. Among the possible isomers, the p,p’-diphenolic acid is that of prevailing interest, because its use leads to superior mechanical and optical properties of the final product. Developing the PRIN 2020 LEVANTE project, the goal of our investigation is the synthesis of a fully renewable p,p’-diphenolic acid, in agreement with the principles of green chemistry. In this context, our research was focused on the diphenolic acid synthesis in the presence of sulfonated hydrochars as acid catalysts, achieving yields about 20 mol%, paving the way for its fully sustainable production.