The general procedure for the synthesis of 2,6-bis((4,6-dimethoxypyrimidin-2-yl)oxy)benzoic acid from 2,6-dihydroxybenzoic acid and 2-methanesulfonyl-4,6-dimethoxypyrimidine was as follows: 0.04 mol of 2,6-dihydroxybenzoic acid, 0.05 mol of 2-methanesulfonyl-4,6-dimethoxypyrimidine, 0.004 mol of tetra butylammonium bromide and 0.08 mol of potassium carbonate in a reaction vessel. 300 mL of toluene was added as a solvent and heated to reflux for 8 to 10 hours. Upon completion of the reaction, the reaction mixture was cooled to room temperature and the solid product was separated by filtration. The filter cake was washed with toluene and subsequently dried. The dried solid product was mixed with 500 mL of water and 30% hydrochloric acid was added slowly and dropwise with stirring to adjust the pH of the system to 3 to 4. It was filtered again and dried to give 15.7 g of the gray solid product 2,6-bis((4,6-dimethoxypyrimidin-2-yl)oxy)benzoic acid with a purity of 97% and a yield of 85%.
