The synthesis of 4-BroMo-9H-carbazoleis as follows：Under the protection of inert gas, 30g zinc powder, 100mL ethanol,100 mL water, 10 mL glacial acetic acid, 22.6 g (0.1 mol) 4-nitrocarbazole was placed in a 500 mL reaction flask, heated to 40 ° C, and kept for 2 h.Stop the reaction when the reaction solution is grayish white, add sodium hydroxide,Adjust the pH of the system to 9, after the reaction system is cooled,The organic layer was extracted by adding 150 mL of dichloromethane, and the organic layer was taken out.Distill off the dichloromethane, and when the product is about to be precipitated, add 150 mL of 40% hydrobromic acid, and add 150 mL of water.The ice water bath was cooled for 30 min; 50 mL of a 20% sodium nitrite aqueous solution (13.7 g, 0.2 mol of sodium nitrite) was added dropwise, and after the dropwise addition was completed,After holding for 30 min, continue to add 200 mL of a 40% aqueous solution of cuprous bromide (21.5 g of cuprous bromide, 0.15 mol);After 2 h of reaction, 10 g of sodium hydrogen sulfite was added to remove excess bromine.The aqueous phase was extracted with 150 mL of dichloromethane and the dichloromethane was evaporated.Then recrystallized by adding 150 mL of methanol.Filtration gave a pale yellow solid of 17.7 g of 4-bromocarbazole with a content of 99.8%.The yield was 72%.
