The curing reaction of 3-aryl substituted benzoxazine

The reaction pathways on the curing reaction of 3-aryl substituted benzoxaz ine was investigated from the model reaction of 3,4-dihydro-6,8-dimethyl-3- phenyl-2H-1,3-benzoxazine (1) with 2,4-xylenol(2). The reaction was carried out at 140 degrees C for 5 h. N,N-Bis(2-hydroxy-3,5-dimethylbenzyl)phenyla mine (3) and N-(2-hydroxy-3,5-dimethylbenzyl)phenylamine (4) were isolated as main products at an early stage. The reaction of 3 by the thermal treatm ent was studied by H-1-NMR spectroscopy. This result indicates that compoun d 3 produces several inter- and intramolecular rearrangement products. Base d on these data, some possible reaction pathways were proposed. In the pres ence of p-toluenesulfonic acid monohydride, 3,3'[4,4'-methylenediphenyl]bis (3,4-dihydro-6,8-dimethyl-2H-1,3-benzoxazine) (9) was isolated as one of th e intermediates.