2-Chloro-5-iodobenzoic acid

89-54-3

19094-56-5

The general procedure for the synthesis of 2-chloro-5-iodobenzoic acid from 5-amino-2-chlorobenzoic acid was as follows: 123 g of 2-chloro-5-aminobenzoic acid was added to 2000 g of 20% aqueous sulfuric acid solution, and the temperature of the reaction was maintained at 0 to 10 °C. An aqueous sodium nitrite solution (51 g sodium nitrite dissolved in 200 g water) was prepared and added drop by drop to the reaction system, and the progress of the reaction was monitored by TLC (unfolding agent ratio of petroleum ether/ethyl acetate = 1:3) during the reaction. Upon completion of the reaction, 1.2 g of urea was added and cooled to 0 °C with stirring, potassium iodide solution (130 g KI dissolved in 500 g of water) was quickly added and stirring was continued until no bubbles were produced and then stirred for 30 min. The reaction mixture was filtered and washed with 200 g of water to give a brown solid. The solid was dissolved in 400 g of ethyl acetate and washed sequentially with 300 mL of 1N hydrochloric acid, 300 mL of 10% sodium bisulfite solution and 400 mL of saturated brine, and the organic phase was dried with magnesium sulfate. After drying, the crude product was obtained by concentration under reduced pressure at 50 °C. The crude product was dissolved in 400 mL of toluene and heated at 80 °C for 1 hour, then cooled to 0-5 °C for 1 hour for crystallization. Finally, it was dried under reduced pressure at 50 °C to give 191 g of 2-chloro-5-iodobenzoic acid as a pale yellow solid with 99.6% purity and 93.7% yield.