N-[3,5-Bis(chlorocarbonyl)-2,4,6-triiodophenyl]amine (100g, 0.17mol) ) was added with 100ml of DMA to dissolve, and methoxyacetyl chloride (27.3g, 0.25mol) was added dropwise at 20°C for about 1 hour. The reaction was kept at 20-30°C for 5-8 hours. Cool the mixture to 5°C, water, potassium carbonate (58.7 g, 0.42 mol), 400 ml of dichloromethane, and 3-amino-1,2-propanediol (17.8 g, 0.2 mol) were added dropwise. After 8 hours, 400 ml of cold water was quickly added to the reaction solution. After crystallization, filtered, washed with a small amount of water, and dried to obtain 5-methoxyacetylamino-2,4,6-triiodoisophthalic acid (2,3-dihydroxypropyl)amide chloride.
