To a 1L autoclave equipped with a mechanical stirrer, a thermometer socket, a manometer and a nitrogen displacement port, 178 g of 2,6-di-tert-butylphenol, 24.48 g of paraformaldehyde, 41.28 g of isocyanuric acid, and 4.4 g of urotropine were added sequentially. The system was vacuumed and nitrogen replacement was repeated more than three times, and after the last nitrogen replacement, 1000 mL of 70% v/v methanol aqueous solution was pumped into the reactor under -0.01 MPa negative pressure. Subsequently, the system was charged with nitrogen to a pressure of 0.6 MPa. Under the nitrogen atmosphere, the temperature was gradually increased to 120°C and maintained for 2 hours, and then continued to increase to 140°C and maintained for 4 hours to complete the reaction. At the end of the reaction, the reactor was cooled to 58°C by circulating water to obtain the crude product. After the crude product was filtered, the solid was dissolved in 70% by volume methanol aqueous solution, cooled and recrystallized. The recrystallized product was washed at least twice with anhydrous methanol at 55 °C and dried to give the white crystalline target product, hindered phenolic antioxidant 3114, in 92.3% yield.
