The general procedure for the synthesis of solvent green 7 from 1,3,6,8-pyrene tetrasulfonic acid tetrasodium salt is as follows: 1,200 g of concentrated sulfuric acid is added to a 2,000 ml three-necked flask with stirring, 120 g of 1,3,6,8-pyrene tetrasulfonic acid tetrasodium salt is added, and the temperature is slowly raised to 90°C and maintained for 1 hour after being slightly heated to promote complete dissolution. Upon completion of the reaction, the reaction mixture was cooled to below 40°C using a water bath, and 480 g of liquid sulfur black was slowly added dropwise, with the dropwise addition process being controlled to be completed within 3 hours. Subsequently, the reaction temperature was maintained at about 100°C to continue the reaction for 5 hours. At the end of the reaction, it was cooled to room temperature, and the reaction mixture was poured into 720 g of ice water to obtain a viscous material, and the filter cake was dried after filtration to obtain pyrene tetrasulfonic acid tetrasodium salt. Next, the tetrasodium salt of pyrene tetrasulfonate was dissolved in 1000 ml of water, transferred to a 2000 ml three-necked flask, adjusted to neutrality with sodium hydroxide solution, and 300 g of flaked sodium hydroxide was added. It was slowly heated to a slight boil and kept for 5 hours. After the reaction was completed, it was cooled, and the pH was adjusted to about 7 with hydrochloric acid, then 100 g of sodium chloride was added and stirred until it was completely dissolved, and a light yellow solid was slowly precipitated. After filtering and drying, about 245 g of 8-hydroxy-1,3,6-pyrene trisodium sulfonate was finally obtained.
