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Process for preparing aloe-emodin

一种芦荟大黄素、芦荟素的技术，应用在制备大黄酸和双醋瑞因领域，能够解决复杂纯化工艺等问题

Active Publication Date: 2007-10-17
LABE MEDIDOM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] However, the known methods of preparing aloe-emodin have several disadvantages in that known synthetic methods require the use of metal reagents, or other harmful or toxic substances, and require complex purification processes to remove the metal reagents or other harmful reagents. the remains

Method used

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  • Process for preparing aloe-emodin

Examples

Experimental program
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Effect test

Embodiment 1

[0113] Crude aloin (72 g, containing 39% pure aloin) was dissolved in ethylene glycol (250 ml). This solution was poured into a one liter reactor and heated to 120°C under a nitrogen atmosphere. Upon reaching a temperature of 120 °C, HNO diluted in ethylene glycol (50 ml) was added over a period of 20 minutes 3 (7.58g). At this point, oxygen was introduced into the reactor through a sparger at a flow rate of 4 L / min. Samples were taken from the reactor every hour for analysis by HPLC to determine the completion of the reaction. After 6 hours, the reaction was complete. Under the above conditions, the conversion rate of aloin into aloe-emodin is 61%.

[0114] Then by continuously pouring the reaction mixture into water, extracting aloe-emodin with toluene or methylene chloride, evaporating toluene or methylene chloride, drying aloe-emodin (purity: 50%), precipitating aloe-emodin in ethanol, filtering aloe-emodin Aloe-emodin and dried aloe-emodin to separate aloe-emodin to ...

Embodiment 2

[0116] Crude aloin (3.24 Kg, containing 36% pure aloin) was dissolved in ethylene glycol (13.5 L) under nitrogen atmosphere. 170 g of nitric acid (dissolved in ethylene glycol) were added over a period of 5 minutes under continuous stirring. The solution was heated to 105°C. At this point, nitrogen was flushed out by introducing an oxygen flow for a period of 10 minutes. The reactor was then pressurized up to a pressure of 1.5 bar absolute by introducing oxygen. The oxygen pressure was maintained at 1.5 bar absolute for 5 min. The reactor was then depressurized to ambient pressure and cooled to room temperature. Under the above conditions, the conversion rate of aloin into aloe-emodin is 80%.

[0117] The aloe-emodin is then isolated. The reaction mixture containing suspended aloe-emodin was passed through a pressurized stainless steel filter press (8 bar absolute, 1 hour). The filter cake was then washed with half volume (7 L) of ethylene glycol under pressure (8 bar ab...

Embodiment 3

[0122] The oxidizing medium was prepared by dissolving sodium nitrite (255 g) in sulfuric acid (1.2 L). The oxidizing medium was heated to 120° C., and then aloe-emodin (100 g) was slowly added thereto. After the oxidation reaction was finished (3 hours), the reaction mixture was poured into distilled water (7.2 L) at 2°C to precipitate rhein, which was filtered and dried. Rhein with a purity of 90-95% was obtained with a yield of more than 85%.

[0123] Purification of Rhein

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Abstract

The present invention provides 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.

Description

Background of the invention [0001] The invention relates to a method for preparing aloe-emodin from aloin. Additionally, methods for preparing rhein and diacerein from aloin are provided. [0002] Diacerein is known to be useful in the treatment of diseases associated with abnormal degeneration of connective tissue, more specifically, in the treatment of inflammatory states of joints and connective tissue such as rheumatoid arthritis, osteoarthritis and osteoporosis, Acute respiratory syndrome, or emphysema, in adults. [0003] The best-known method for preparing diacerein from aloin involves acetylation of aloin followed by chromium oxidation of the acetylated product to obtain diacerein. [0004] For example, WO-A-98 56750 (Synteco) discloses a process for the preparation of diacerein from aloin, which involves acetylating aloin to obtain acetylaloe vera, using a solution of chromic anhydride in acetic acid The oxidizing agent oxidizes acetyl aloin to obtain crude diacere...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/27C07C66/02C07C67/08C07C69/16
CPCC07C66/02A61P11/00A61P19/02A61P19/10A61P29/00A61P35/00
Inventor S·卡里诺G·迪纳伯利
Owner LABE MEDIDOM
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