Method of preparing rhein

A technology of rhein and aloe-emodin, which is applied in the directions of oxidative preparation of carboxylic acid and the like, can solve problems such as environmental pollution, achieve the effects of easy availability of raw materials, good promotion and application prospects, and reduction of environmental pollution

Inactive Publication Date: 2009-08-19
ZHEJIANG UNIV OF TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This method also has problems such as serious environmental pollution due to using a large amount of potassium permanganate

Method used

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  • Method of preparing rhein
  • Method of preparing rhein
  • Method of preparing rhein

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] In the 100ml reaction vessel, drop into aloe-emodin (5.4g, 20mmol), then drop into the aqueous solution 4ml of nitric acid whose concentration is 5mol / L, and stir until all the solids are dissolved. Calcium hypochlorite (11.4 g, 80 mmol) was added at a temperature of 20°C, and the temperature was raised to 50°C within 10 minutes to react for 3 hours. After the reaction was over, the reaction solution was poured into ice water to precipitate solids, filtered, and the filter cake was washed with water until the filtrate was neutral, recrystallized with glacial acetic acid, filtered, and dried to obtain 4.21 g of rhein, with an HPLC purity of 98.1%. The rate is 73.2%.

Embodiment 2

[0024] Drop into aloe-emodin (5.4g, 20mmol) in the 100ml reaction container, then drop into concentration and be the aqueous solution 40ml of the nitric acid of 5mol / L, stir until solid all dissolves. Calcium hypochlorite (11.4 g, 80 mmol) was added at a temperature of 40° C., and the temperature was raised to 60° C. within 10 minutes to react for 3 hours. After the reaction was over, the reaction solution was poured into ice water to precipitate solids, filtered, and the filter cake was washed with water until the filtrate was neutral, recrystallized with glacial acetic acid, filtered, and dried to obtain 5.23 g of rhein, with an HPLC purity of 98.5%. The rate is 91.2%.

Embodiment 3

[0026] Drop into aloe-emodin (5.4g, 20mmol) in 100ml reaction vessel, then drop into concentration and be the aqueous solution 60ml of the nitric acid of 5mol / L, stir until solid all dissolves. Calcium hypochlorite (11.4 g, 80 mmol) was added at a temperature of 40° C., and the temperature was raised to 80° C. within 10 minutes to react for 3 hours. After the reaction was over, the reaction solution was poured into ice water to precipitate solids, filtered, and the filter cake was washed with water until the filtrate was neutral, recrystallized with glacial acetic acid, filtered, and dried to obtain 5.51 g of rhein, with an HPLC purity of 98.8%. The rate is 96.5%.

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Abstract

The invention discloses a method for the preparation of rhein having a structure represented by the formula (II), comprising the steps of: adding into a reaction vessel aloe emodin represented by the formula (I) and aqueous solution of inorganic acids, stirring until solids are completely dissolved, feeding an oxidant at the temperature ranging from 20 to 50 DEG C, with amount ratio of the oxidant to the aloe emodin of 0.5-10:1, after feeding the oxidant, heating up to 50 to 90 DEG C for reaction, tracing the reaction progress by means of TLC, detecting the amount of the diacerein to measure a reaction endpoint, upon finish of the reaction, pouring reaction solution into icy water to separate out solid, filtering, washing filter cake with water until the filtrate is neutral, and then obtaining the rhein via recrystalliation by glacial acetic acid, filtering and drying; the amount ratio of the aloe emodin to organic acid feeding substances is 1:1-20. The invention has the advantages of great availability of raw material, simple processes, small use amount of solvent, higher yield and purity of the obtained products and no residues of harmful metal ions, and is a preparation method for the rhein having favorable popularization and application prospect.

Description

(1) Technical field [0001] The invention relates to a preparation method of rhein. (2) Background technology [0002] Rhein is a yellow needle-like crystal. Insoluble in water, slightly soluble in ethanol, chloroform, ether, petroleum ether and benzene. It is commercially available in two forms, the red potassium salt and the pink sodium salt. Rhein has high medicinal value and is widely used in various medicines. So far, research on the medicinal activity of rhein has found that rhein has various effects such as antibacterial, antitumor, immunosuppressive, diuretic, purgative, anti-inflammatory, and treatment of diabetic nephropathy. Moreover, many derivatives with better biological activity can be obtained through structural modification and transformation of rhein. More importantly, rhein is a key intermediate in the preparation of diacerein (diacetylrhein), and diacerein is a new type of interleukin 1β (1L-1β) inhibitor, which can significantly relieve Osteoarthriti...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C66/02C07C51/16
Inventor 苏为科朱兴一张志敏
Owner ZHEJIANG UNIV OF TECH
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