Synthesis
Trimellitic anhydride (1.0 mol, 192 g) was mixed with ethylene glycol (0.55 mol, 34 g) in a reactor and nitrogen was vented to remove air. The reaction mixture was heated to 230-240°C under continuous nitrogen protection, during which water was generated and distilled. When the amount of water distilled approached the theoretical value (18 g), the system pressure was reduced to 10-15 mmHg while the temperature was raised to 260°C and the reaction was maintained at this condition for 2 hours. Upon completion of the reaction, the reaction mixture was cooled and recrystallized from 900-1200 g of acetone to afford the intermediate ethylene glycol trimellitate as a white powder (176 g, 86% yield). Subsequently, the intermediate was dissolved in 5% aqueous sodium hydroxide solution and hydrolyzed by adjusting the pH to 1-3 with dilute hydrochloric acid, and dried after completion of the reaction to obtain the final product ethylene glycol trimellitate as white powder (211.8 g, 95% yield).
