4-Nitrophenol employed in Scheme 8 is a light yellow powder that immediately colors benzoxazines and benzoxazine-containing solutions bright red. The reaction product from nitrothiophenol and phenyl benzoxazine is a yellow solid. The reaction was run in a variety of deuterated solvents,including chloroform, acetone, methanol, and DMSO. Theproduct precipitates out of chloroform and,if moderately concentrated, from acetone, but in methanol and DMSO the reaction proceeds readilyto completion.