Barbituric acid (BA) cannot be used for synthesis of oligoetherols in a straightforward reaction with ethylene oxide (EO) or propylene oxide (PO) or alkylene carbonates because it undergoes tautomeric conversion into the tri-enolic form. The latter is insoluble in oxiranes and alkylene carbonates and does not react with them further. This obstacle was eliminated by initial functionalization of BA with glycidol (GL) leading to hydroxyalkyl derivatives of BA. The hydroxyalkyl derivatives of BA dissolve easily in oxiranes or in alkylene carbonates like ethylene (EC) or propylene (PC) carbonates and react with them to give oligoetherols with enhanced thermal stability.
Kania, E., & Lubczak, J. (2014). New method of synthesis of oligoetherols with pyrimidine ring from barbituric acid and glycidol. Polimery, 59(11-12), 851–854. https://doi.org/10.14314/polimery.2014.851
References
“Dictionary of Organic Compounds”, Vol. V, Eyre and Spottivoode Publishers, New York University