An electric stirrer, reflux condenser and thermometer were assembled in each of the four reaction bottles. To each reaction vial was added 20.3 g of m-toluene dicarbonyl chloride, 36 g of 2,2,6,6-tetramethylpiperidinamine, 60 g of solvent, and 1.5 g of catalyst. the stirrer was started, heated to 110 °C and started to time, and the reaction time ranged from 4.5 to 10 hours. Upon completion of the reaction, the reaction mixture was slowly added to an alkaline aqueous solution under strong stirring to remove unreacted isophthaloyl chloride. Subsequently, the mixture was cooled to 15-20°C to promote crystallization. The crystallized product was collected by filtration to afford N1,N3-bis(2,2,6,6-tetramethylpiperidin-4-yl)isophthalamide. The light stabilizer had a yield of 97.38% and a melting point of 270-275 °C.
