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Esterification method of catechin or tea polyphenol

A technology for tea polyphenols and catechins, applied in the field of esterification of catechins or tea polyphenols, can solve the problems of difficult separation, low acylation ability of carboxylic acids, weak activity of carboxylic acids and phenols, etc.

Active Publication Date: 2015-02-04
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In the prior art, when an organic carboxylic acid is used as an acylating agent, due to the low acylation ability of the carboxylic acid, it must be activated with a catalyst
The direct esterification of carboxylic acid and alcohol can be catalyzed by dehydrating agents such as DCC (dicyclohexylcarbodiimide), but the activity of DCC to catalyze the direct esterification of carboxylic acid and phenol is not strong, and after catalyzing the esterification of phenol Transform into dicyclohexyl urea, which is difficult to separate and easily contaminates the product

Method used

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  • Esterification method of catechin or tea polyphenol

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0083] Dissolve 1.78g (11mmol) of CDI in 50mL of ethyl acetate, add 0.60g (10mmol) of acetic acid, heat to reflux, and stir the reaction until no gas is released. Solution is cooled to 60 ℃, adds 0.47g (1.0mmol) EGCG (purity 97%, the same below), under N 2 Under protection, continue to heat and reflux for 2 hours. Cool to room temperature, add 50mL of 0.5M HCl, stir for 2min, separate to remove the water phase, wash with 2×50mL (represents washing twice, each time 50mL, the same below) saturated brine, dry over anhydrous sodium sulfate, filter, The solvent was removed by rotary evaporation, and the obtained solid was recrystallized from ethanol-water to obtain 0.76 g of a white solid after drying. The H-NMR analysis result was consistent with the EGCG peracetate reported in the literature, and the yield was 96%.

Embodiment 2

[0085] Dissolve 2.09g (11mmol) of 1,1□-carbonylbis(2-methylimidazole) in 50mL of tetrahydrofuran, add 0.60g (10mmol) of acetic acid, heat to reflux, and stir the reaction until no gas is released. Cool the solution to 60°C, add 0.47g (1.0mmol) EGCG, and 2 Under protection, continue to heat and reflux for 2 hours. Cool to room temperature, add 1.5M HCl dropwise with stirring until the pH of the solution is about 2, continue to add 100mL distilled water dropwise, filter with suction, and wash with water until neutral. The resulting solid was recrystallized from tetrahydrofuran-water, and dried in vacuo to obtain 0.75 g of EGCG peracetate as a white solid, with a yield of 94%.

Embodiment 3

[0087] 1.0g (14.7mmol) imidazole and 0.47g (1.0mmol) EGCG were dissolved in 30mL acetone, in N 2 Under protection, a 20 mL acetone solution containing 1.1 g (14 mmol) of acetyl chloride was added dropwise, and the reaction was stirred. After the dropwise addition was completed, it was heated to reflux, and the stirring reaction was continued for 2 hours. Cool to room temperature, add 10mL of 0.1M HCl, then dropwise add 150mL of distilled water under stirring, filter with suction, wash with water until neutral, and dry in vacuo. The obtained solid was separated and purified by silica gel column chromatography (ethyl acetate / petroleum ether 3:1, v / v) to obtain 0.78 g of EGCG peracetate as a white solid, with a yield of 98%.

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Abstract

The invention discloses an esterification method of catechin or tea polyphenol. In the esterification method, a catalyst for esterification is carbonyl diimidazole and / or imidazole. The esterification method comprises esterification between an organic carboxylic acid and the catechin or the tea polyphenol with catalysis of the carbonyl diimidazole, or the esterification between an anhydride or an acyl chloride and the catechin or the tea polyphenol with synergetic catalysis of the imidazole and / or the carbonyl diimidazole. The carbonyl diimidazole is a strong dehydrating agent and can eliminate influence of water on the esterification in the reaction system. The carbonyl diimidazole can effectively activate carboxylic acid so that not only can the carboxylic acid be used as an acylation reagent, but also free carboxylic acids existing in the esterification of the anhydride or the acyl chloride can be fully utilized, so that esterification degree of esterification products can be conveniently controlled according to proportion of raw materials and a residual amount of the free carboxylic acids after reaction is less. Meanwhile, the carbonyl diimidazole and the imidazole is very easy to separate from the esterification products, thereby greatly enabling separation and purification of the products to be convenient.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, and in particular relates to an esterification method of catechins or tea polyphenols. Background technique [0002] Tea polyphenols are tea extracts with catechins as the main components. The catechins are mainly composed of C, EC, EGC, ECG, EGCG and GCG, and the content of EGCG is the highest. Catechin has won the attention and favor of the world for its superior biological and pharmacological activities. With the deepening of research, its application field is expanding continuously. However, catechins and tea polyphenols are easily soluble in water but poorly soluble in oil, have a small oil-water partition coefficient and low bioavailability, which limits their application fields and inhibits their physiological and pharmacological activities. [0003] There are three main methods to enhance the solubility of catechin compounds in oils: solvent method, emulsification method and m...

Claims

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Application Information

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IPC IPC(8): C07D311/62
CPCC07D311/62
Inventor 钟建华
Owner ZHEJIANG UNIV
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