Isomeric Speciation\nof Bisbenzoxazine Intermediates\nby Ion Spectroscopy and Ion Mobility Mass Spectrometry

Bisbenzoxazines (<b>BisBz</b>) are a relevant model\nfor the\ndiverse bifunctional benzoxazines that are used to increase the polybenzoxazines\ncross-linking extensions and modulate the final resin properties for\nvarious usages. The presence of side products and intermediates during\nmonomer formation can influence the resin characteristics by inducing\nchain termination and ramifications, affecting the polymerization\nand cure processes. This work investigated the diverse isomeric intermediates\nand side products that are present during the <b>BisBz</b> formation\nfrom bisphenol A, aniline, and formaldehyde by ion mobility coupled\nto <i>tandem</i> mass spectrometry (MS/MS) and ion spectroscopy\ntechniques. The species detected in this work suggest that these multifunctional\nphenols open diverse concurrent reaction pathways based on two main\nreactive steps: (i) the imine/iminium phenol attack to form a phenylamino\nintermediate and (ii) the formaldehyde attack followed by dehydration\nto form the oxazine ring. The species observed also support previous\nstudies of the benzoxazine formation mechanism and showcase the application\nof advanced analytical techniques in studying complex chemical systems.