The classic synthesis method is glacial acetic acid as acylating agent and zinc chloride as catalyst, but the decolorization is difficult and the yield is not high, mostly 60%~8%; Acetic anhydride Chemicalbook is also used as acylating agent and ion exchange resin as catalyst; There are also acetyl chloride, acetonitrile as acylating agents, and SnCl as catalysts, but these methods are not suitable for industrialization.