Emodin was synthesized by demethylation of physcion.Three catalysts of demethylation, AlCl3, H2SO4 and HBr, were compared.

• 摘要目的与方法将大黄素甲醚脱甲基制备大黄素，对以三氯化铝、浓硫酸、氢溴酸作为催化剂的3种方法进行比较。