Diphenolic acid is emerging as a bio-based alternative to the toxic bisphenol A in the production of epoxy resins, polycarbonates, and isocyanate-free polyurethanes, finding applications also as an additive in fire-retardant materials and painting formulations. Typically, it is synthesized through the solvent-free condensation between two molecules of phenol and levulinic acid in the presence of a Brønsted acid catalyst. Mineral acids, such as hydrochloric and sulfuric acid, are conventionally used as homogeneous catalysts, anyway showing important disadvantages connected with their use, such as corrosion issues and intensive work-up within the wastewater treatment. Heterogeneous catalysts offer a more environmentally friendly alternative due to their safety and ease of separation from the reaction mixture. Together with the formation of diphenolic acid, esterification of levulinic acid may occur as a side reaction, decreasing the selectivity to the desired product. New synthetic routes involving novel heterogeneous catalysts and substrates can be investigated. The reactivity of levulinic acid can be slowed by using ethyl levulinate instead of the acid, as the trans-esterification rate is typically slower than esterification with standard acid catalysts. Therefore, ethyl levulinate can be used as a substrate to improve selectivity. In this study, a catalytic screening was conducted to identify catalysts exhibiting the most promising performances in the reaction involving levulinic acid/ethyl levulinate and phenol. Various catalysts, including both homogeneous and heterogeneous ones, were tested, focusing the attention both on commercial and synthetic ones. Among the catalysts commercially available, sulfuric acid, zeolites including H-Y Zeolite and β-Zeolite, and sulfonic acid resins, such as Amberlite IR120, Dowex 50WX8, and Amberlyst-15, were tested. Additionally, synthetic catalysts, such as sulfonated hydrochars, were also considered. Therefore, a feasibility study was conducted to identify the catalyst with promising characteristics with the aim to perform the reaction in a continuous device.
DPA synthesis: a feasibility study towards the continuous application
Domenico Licursi;Claudia Antonetti;Anna Maria Raspolli Galletti;
2024-01-01
Abstract
Diphenolic acid is emerging as a bio-based alternative to the toxic bisphenol A in the production of epoxy resins, polycarbonates, and isocyanate-free polyurethanes, finding applications also as an additive in fire-retardant materials and painting formulations. Typically, it is synthesized through the solvent-free condensation between two molecules of phenol and levulinic acid in the presence of a Brønsted acid catalyst. Mineral acids, such as hydrochloric and sulfuric acid, are conventionally used as homogeneous catalysts, anyway showing important disadvantages connected with their use, such as corrosion issues and intensive work-up within the wastewater treatment. Heterogeneous catalysts offer a more environmentally friendly alternative due to their safety and ease of separation from the reaction mixture. Together with the formation of diphenolic acid, esterification of levulinic acid may occur as a side reaction, decreasing the selectivity to the desired product. New synthetic routes involving novel heterogeneous catalysts and substrates can be investigated. The reactivity of levulinic acid can be slowed by using ethyl levulinate instead of the acid, as the trans-esterification rate is typically slower than esterification with standard acid catalysts. Therefore, ethyl levulinate can be used as a substrate to improve selectivity. In this study, a catalytic screening was conducted to identify catalysts exhibiting the most promising performances in the reaction involving levulinic acid/ethyl levulinate and phenol. Various catalysts, including both homogeneous and heterogeneous ones, were tested, focusing the attention both on commercial and synthetic ones. Among the catalysts commercially available, sulfuric acid, zeolites including H-Y Zeolite and β-Zeolite, and sulfonic acid resins, such as Amberlite IR120, Dowex 50WX8, and Amberlyst-15, were tested. Additionally, synthetic catalysts, such as sulfonated hydrochars, were also considered. Therefore, a feasibility study was conducted to identify the catalyst with promising characteristics with the aim to perform the reaction in a continuous device.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
