Exploring the Reactivity of Amines with Cyclic Carbonates for Tailored Urethandiol Synthesis

ABSTRACT This work presents a systematic investigation into the solvent‐free aminolysis of industrially relevant cyclic carbonates‐specifically ethylene carbonate (EC) and propylene carbonate (PC)‐with a series of structurally diverse diamines. The primary objective is to establish practical structure‐reactivity relationships that, enable the rational synthesis of hydroxy‐terminated urethane diols. These diols are subsequently evaluated as building blocks for the preparation of non‐isocyanate urethane (meth)acrylates (NIU(M)As). By employing diamines in place of toxic diisocyanates, this synthetic strategy not only circumvents the use of conventional isocyanate chemistry, but also significantly expands the accessible structural diversity of urethane (meth)acrylates, including architectures that are difficult or impossible to obtain through traditional routes. The aminolysis reaction was monitored in real time by ATR‐FTIR spectroscopy, tracking the consumption of the carbonate C═O bond, and was complemented by residual amine titration. The structures of the resulting urethane diols and their NIU(MA) derivatives were confirmed by NMR spectroscopy. The study reveals clear, structure‐dependent reactivity trends: aliphatic diamines undergo rapid ring‐opening under mild conditions (40°–75°C), whereas aromatic diamines show no measurable conversion, even at elevated temperatures. This contrast underscores the dominant role of amine nucleophilicity in determining reaction kinetics. Furthermore, aminolysis of the unsymmetrical PC yields mixtures of regio isomeric urethane diols containing primary and secondary hydroxyl groups depending on the structure of amine, a direct consequence of competing ring‐opening pathways. To demonstrate the practical utility of this approach, a representative urethane diol was successfully converted into a NIU(M)A derivative. The product was characterized by NMR, IR, GPC, and photo‐DSC, confirming the viability of this synthetic route for producing UV–curable formulations. These findings provide critical insights into the interplay between cyclic carbonate structure, amine reactivity, and product selectivity. This work thereby supports the rational design and development of advanced, non‐isocyanate‐based urethane materials for a range of potential applications.