Sintesi dell´etilestere dell´acido difenolico promossa da catalizzatori acidi

The present invention concerns the obtaining of diphenolic acid (DPA) ethyl esters, starting from ethyl levulinate and phenol in the presence of acid catalysts, with high selectivity to give the p,p-DPA isomer, useful for the synthesis of isocyanate-free polyurethane foams (NIPU). The proposed synthesis route is an alternative to the classical one, in which levulinic acid is used, a synthesis strategy that suffers from selectivity since the p,p/o,p ratio is particularly low (generally equal to 3).