Core Raw Material: Phthalic anhydride (CAS No.: 85-44-9)
Chlorination Reagent: Chlorine (Cl₂)
Solvent/Catalyst: Depending on the process, fuming sulfuric acid, chlorosulfonic acid, iodine, or Lewis acids (such as FeCl₃, CoCl₂) can be used.
Solvent Method: Phthalic anhydride is dissolved in fuming sulfuric acid or chlorosulfonic acid, iodine or iodine chloride is added as a catalyst, and chlorine gas is passed through to carry out an electrophilic substitution reaction.
Melting Method: Phthalic anhydride is chlorinated directly with chlorine gas in the molten state, using Mg, Fe, Sb, etc. as catalysts.
Gas-Phase Method: Phthalic anhydride undergoes gas-phase chlorination at high temperatures of 200–400℃ catalyzed by Lewis acids.
