Process for preparing aloe-emodin

摘要

A process for preparing aloe-emodin from aloin by oxidizing aloin by treatment with an oxygen-containing gas in the presence of an acid. The aloe-emodin may be used for the production of rhein and diacerein by oxidizing aloe-emodin by treatment with a chromium-free oxidizing medium to obtain rhein and purifying the rhein obtained. The rhein may be acetylated to obtain diacerein.