Introduction. 2-Isopropenyl-2-oxazoline (iPOx) is a monomer belonging to the 2-oxazolines class. Unlike typical 2-oxazolines that undergo ring-opening polymerization, iPOx polymerizes via its vinyl group, retaining the 2-oxazoline functionality which offers valuable sites for post-polymerization modifications, especially with carboxylic compunds. Thus, iPOx serves as a versatile building block for the design of functional (co)polymers. Conventional synthesis routes for iPOx often involve harsh conditions, limiting their practicality and scalability. This study explores multiple synthetic routes for the preparation of iPOx, aiming to establish a more accessible and practical method.
Methods. The synthesis followed well-established protocols, starting from methacrylic acid or its derivatives, which are reacted with aminoalcohols or haloalkylamines in various solvents. The resulting hydroxyamides or haloamides were then cyclized to obtain the final product, iPOx.
Results. Several synthetic routes were evaluated for the preparation of iPOx, varying the starting methacrylate derivatives, nucleophiles, and solvents. Reactions using methacrylic anhydride and 2-chloroethylamine yielded the highest purity intermediates, which were efficiently cyclized to iPOx under basic conditions. Hydroxyamide-based routes also produced good yields although they required harsher conditions during the cyclization step. Overall, the optimized pathway demonstrated improved scalability, reduced reaction times, and minimized byproduct formation compared to conventional methods. FTIR and NMR spectroscopy was used for structural confirmation of intermediates.
Conclusions. This study systematically evaluated various synthetic routes for the preparation of iPOx. The influence of the starting materials and reaction conditions on the reaction yield and purity of the final compound was also assessed. The optimized synthesis protocol provided a more practical and scalable route to iPOx, with improved efficiency and reduced byproduct formation.
