Resorcinol is an important organic synthetic material, mainly used in rubber adhesive, analytical reagent, preservative, medicine, dye, synthetic resin and other raw materials. For example, Shuhong is an important triphenylmethane dye, dyed with bright red, mainly used for dyeing silk. It is used to prepare intermediate fluorescent yellow by CO heating of Resorcinol and phthalic anhydride in the presence of zinc chloride or concentrated sulfuric acid, It is prepared by tetrabromination. Eosin is commonly used to make red ink, and can also be used as a dye for microscopic examination of biomaterials. If the intermediate fluorescent yellow is brominated in the acetic acid solution, only dibromylation can be carried out, and then the red mercury (also called amalgam) can be obtained by CO heating with mercury acetate. It is an important antiseptic. It is easy to dissolve in water, 2% of the water solution is the "red medicine water" used for daily sterilization and disinfection. The alcohol acetone solution of mercury can also be used for skin disinfection. 4-n-hexanediol can be obtained by acylation of resorcinol and caproic acid, which is also a disinfectant. It is also used as local anti itching agent and intestinal digestive agent in medicine.