Formaldehyde → Dihydrobenzoxazine

33.2 g (0.2 mole) of dicyclopentadiene novolac (hereinafter abbreviated as DCPDNO) and 32.4 g of aqueous formaldehyde (37%, 0.4 mole) were added into a 4-neck reactor equipped with a stirrer, temperature controller, and condenser, and then 100 ml of 1,4-dioxane was added as a solvent. The mixture was stirred at room temperature, and to the resulting solution 18.6 g (0.2 mole) aniline in 30 ml 1,4-dioxane was dripped at a rate of one drop per second while stirring. Upon completion of the dripping the solution was heated and reacted under refluxing for five hours. The reaction mixture was dried in a rotary evaporator under vacuum to obtain a dark brown solid. The dark brown solid was dissolved in ethyl ether and washed with 3N aqueous NaOH three times, followed by 1 N aqueous HCl solution several times and pure water several times, before removing the solvent in vacuo to obtain DCPDNO dihydrobenzoxazine solid. The solid was ground to light brown powder. Softening point (SP) 143° C.