One‐Pot Alkoxylation of Phenols with Urea and 1,2‐Glycols

A one‐pot epoxide‐free alkoxylation process has been developed for phenolic compounds. The process involves heating phenols and urea in 1,2‐glycols at 170‐190 °C using Na₂CO₃/ZnO as co‐catalysts under atmospheric conditions. During the course of this new alkoxylation reaction, a five‐membered ring cyclic carbonate intermediate, ethylene carbonate (EC) or propylene carbonate (PPC), was produced in‐transit as the key intermediate and was subsequently consumed by phenols to form alkoxylated ether alcohols as final products in excellent yields. For instance, phenol, bisphenol A (BPA), hydroquinone and resorcinol were converted into their respective mono‐alkoxylated ether alcohols on each of their phenolic groups in 80‐95% isolated yields. In propoxylation of phenols, this approach shows great product selectivity favoring production of high secondary alcohols over primary alcohols in isomeric ratios of nearing 95/5. Since ammonia (NH₃) and carbon dioxide (CO₂) evolving from the reaction can be re‐combined in theory into urea for re‐use, the overall net‐alkoxylation by this approach can be regarded as a simple condensation reaction of phenols with 1,2‐glycols giving off water as its by‐product. This one‐pot process is simple, safe and environmentally friendlier than the conventional alkoxylated processes based on ethylene oxide (EO) or propylene oxide (PO). Moreover, this process is particularly well‐suited for making short chain‐length alkoxyether alcohols of phenols.