Strategies to Enhance the Reaction Efficiency: A Model Study Using Bisphenol A, Hexylamine, and Formaldehyde for the Synthesis of 1,3-Benzoxazine Monomer.

The present work demonstrates the feasibility of conducting the synthesis of benzoxazines under room temperature conditions without sacrificing good reaction yields using a model benzoxazine based on bisphenol A, hexylamine, and formaldehyde (BA-hex). It also presents the identification of the key crude products participating in the reaction. Understanding their chemical structure and role is important to then be able to enhance the reaction efficiency. This was possible by carrying out the reaction in different solvents. Based on these results, a possible reaction path is proposed, which applies to the synthesis of benzoxazines independently of the temperature at which it is conducted. Carrying out the reaction at elevated temperatures shows no significant difference using any solvent, whereas the best solvent to carry out this reaction at room temperature is also proposed.