1779-11-9

1779-10-8

1779-11-9

The general procedure for the synthesis of 3-hydroxy-7-bromo-2-naphthalenecarboxylic acid from 1,6-dibromo-2-hydroxynaphthalene-3-carboxylic acid was as follows: in a 1L three-necked flask, 40 g of 4,7-dibromo-3-hydroxy-2-naphthalenecarboxylic acid (0.116 mol) and 500 ml of glacial acetic acid were added, and the mixture was stirred thoroughly until uniform. Subsequently, 18 g of tin powder (0.153 mol) and 130 ml of concentrated hydrochloric acid were sequentially added to the reaction mixture. The reaction mixture was heated to 125°C and the reaction was refluxed at this temperature for 12 hours. After completion of the reaction, 300 ml of water was added to the mixture and cooled to room temperature with stirring. The reaction mixture was filtered and the filter cake was washed twice with 200 ml of water. Finally, the filter cake was dried in an oven to give 29.9 g of the target product 3-hydroxy-7-bromo-2-naphthalenecarboxylic acid in 96.5% yield.