Intermolecular hydrogen bonding effects on the reaction of dianisidine, bisphenol A (BPA) and formaldehyde

Abstract

The synthesis of benzoxazines is a fundamental step in obtaining polybenzoxazine resins, understanding its formation mechanism is important to improve the properties of these resins. This paper analyses the Mannich-type reaction between o-dianisidine, bisphenol A (BPA) and formaldehyde. Spectroscopic studies and computational calculations revealed that this reaction only produced a monobenzoxazine, resulting from the formation of cyclic arrays by intermolecular hydrogen bonds between o-dianisidine and BPA. Such cyclic arrays prevented bifunctional benzoxazine and/or oligomer formation.

Keywords

• Mannich reaction
• Dianisidine
• Formaldehyde
• Benzoxazine
• Bisphenol