Ribeiro Francisco W M, Silva-Oliveira Danilo, Cervi Gustavo, Koyanagui Eduardo D, Correra Thiago C
Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748, Cidade Universitária, São Paulo, São Paulo 05508-000, Brazil.
ACS Omega. 2024 Sep 18;9(39):40932-40940. doi: 10.1021/acsomega.4c06205. eCollection 2024 Oct 1.
Bisbenzoxazines () are a relevant model for the diverse bifunctional benzoxazines that are used to increase the polybenzoxazines cross-linking extensions and modulate the final resin properties for various usages. The presence of side products and intermediates during monomer formation can influence the resin characteristics by inducing chain termination and ramifications, affecting the polymerization and cure processes. This work investigated the diverse isomeric intermediates and side products that are present during the formation from bisphenol A, aniline, and formaldehyde by ion mobility coupled to mass spectrometry (MS/MS) and ion spectroscopy techniques. The species detected in this work suggest that these multifunctional phenols open diverse concurrent reaction pathways based on two main reactive steps: (i) the imine/iminium phenol attack to form a phenylamino intermediate and (ii) the formaldehyde attack followed by dehydration to form the oxazine ring. The species observed also support previous studies of the benzoxazine formation mechanism and showcase the application of advanced analytical techniques in studying complex chemical systems.
双苯并恶嗪是多种双功能苯并恶嗪的相关模型，这些双功能苯并恶嗪用于增加聚苯并恶嗪的交联延伸，并调节最终树脂的性能以用于各种用途。单体形成过程中副产物和中间体的存在会通过引发链终止和支化来影响树脂特性，从而影响聚合和固化过程。这项工作通过离子淌度与质谱联用（MS/MS）和离子光谱技术，研究了由双酚A、苯胺和甲醛形成双苯并恶嗪过程中存在的各种异构中间体和副产物。在这项工作中检测到的物种表明，这些多功能酚基于两个主要反应步骤开启了不同的并发反应途径：（i）亚胺/亚胺鎓酚进攻以形成苯基氨基中间体；（ii）甲醛进攻随后脱水以形成恶嗪环。观察到的物种也支持了先前关于苯并恶嗪形成机理的研究，并展示了先进分析技术在研究复杂化学体系中的应用。
