Abstract Two kinds of pyrogallol-based di-benzoxazines (PG-FA and PG-A) with a free phenolic hydroxyl between two oxazine rings attaching to the same benzene were synthesized. The chemical structures of PG-FA and PG-A were identified by 1H NMR, 13C NMR and FTIR tests. The ring-opening polymerization (ROP) behavior of PG-FA and PG-A was monitored by DSC, TGA, FTIR and in situ FTIR measurements. The pyrogallol-containing benzoxazines showed latent catalytic activity as they reached melting condition. The inter- and intramolecular hydrogen bonds from the phenolic hydroxyl and oxygen or nitrogen were converted into weak OH⋯π intramolecular hydrogen bonding, which easily released the free phenolic hydroxyl. Then, the free hydroxyl could accelerate the breakage of oxazine ring. The para-position of free phenolic hydroxyl in pygarollol-based benzoxazines was preferentially polymerized with the carbocations. The temperature-dependent evolution of the chemical structure of PG-FA and PG-A on ROP was consistent with the change of hydrogen bonds.

中文翻译：

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具有潜在催化特性的邻苯三酚基苯并恶嗪：氢键对开环聚合的温度依赖性影响

摘要 合成了两种邻苯三酚基二苯并恶嗪（PG-FA 和PG-A），在连接到同一个苯上的两个恶嗪环之间具有游离酚羟基。PG-FA和PG-A的化学结构通过1H NMR、13C NMR和FTIR测试确定。PG-FA 和 PG-A 的开环聚合 (ROP) 行为通过 DSC、TGA、FTIR 和原位 FTIR 测量进行监测。含连苯三酚的苯并恶嗪在达到熔化条件时表现出潜在的催化活性。酚羟基与氧或氮的分子间和分子内氢键转化为弱的OH⋯π分子内氢键，容易释放游离的酚羟基。然后，游离羟基会加速恶嗪环的断裂。基于苯并恶嗪的苯并恶嗪中游离酚羟基的对位优先与碳正离子聚合。ROP上PG-FA和PG-A化学结构的温度依赖性演化与氢键的变化一致。