Synthesis method of ethyl gallate

A technology of ethyl gallate and a synthesis method, which is applied in the field of synthesis of ethyl gallate, can solve the problems of low yield rate of finished products, influence on the conversion rate of gallic acid, and high product cost, so as to achieve improved conversion rate and stable and reliable production process , The effect of cost reduction

Inactive Publication Date: 2014-10-08
遵义林源医药化工有限责任公司
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Problems solved by technology

The main disadvantage of this synthetic method is that the finished product yield of ethyl gallate is very low, only 60-70%, so the product cost is very high, and there are two main reasons for the low finished product yield: one is in the ester In the chemical reaction system, concentrated sulfuric acid is both a catalyst and a dehydrating agent, and the dosage is about 0.3 to 0.4 (the mass ratio of gallic acid to concentrated sulfuric acid is 1:0.3 to 0.4), and concentrated sulfuric acid is also a strong oxidant. It is carried out under higher temperature conditions, so the concentrated sulfuric acid has a strong oxidation effect on the raw material gallic acid participating in the reaction and the reaction product ethyl gallate at the same time, and even burns; the second is that the water generated in the esterification reaction cannot It is completely absorbed by the dehydrating agent concentrated sulfuric acid, so when the reaction system reaches equilibrium, the esterification reaction is difficult to proceed in the positive direction, which directly affects the conversion rate of gallic acid
How to solve the problems existing in the existing technology has become a difficult research topic to be solved in the field of fine chemical industry

Method used

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  • Synthesis method of ethyl gallate
  • Synthesis method of ethyl gallate
  • Synthesis method of ethyl gallate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] ①Add 100g of gallic acid, 500ml of anhydrous alcohol, and 10g of catalyst concentrated sulfuric acid into a three-necked flask; connect the constant pressure dropping funnel in turn (200g of water-absorbing molecular sieves are installed inside, and the molecular sieves are 3A molecular sieves, which must be dried in a drying oven to Anhydrous), rectification column (installed with glass filler), condensation pipe (through cooling water), thermometer (kettle temperature is controlled at 85-90°C, top temperature is controlled at 80-85°C), and electric heating with magnetic stirring Cover with heat (outside the three-necked flask), and react for 10 hours. (For the esterification reaction device, see the instruction manual figure 1 ).

[0017] ② After the reaction, distill the excess alcohol to recover 430 ml of ethanol, add 500 ml of soft water to cool and crystallize.

[0018] ③Coarsely filter the crude filtrate after 24 hours of crystallization to obtain 144.5 g of ...

Embodiment 2

[0022] ① Add 200g of gallic acid, 1000ml of absolute alcohol, and 20g of catalyst concentrated sulfuric acid into a three-necked flask. Connect to the constant pressure dropping funnel (400 g of water-absorbing molecular sieve is installed inside, the molecular sieve is 3A molecular sieve, and must be dried in a drying oven until there is no water before use), the rectification tower (installed with glass filler), and the condenser tube (through Cooling water), thermometer (kettle temperature is controlled at 85-90°C, top temperature is controlled at 80-85°C), heated on a magnetic stirring electric heating mantle, and reacted for 10 hours.

[0023] ②After the reaction, distill the excess alcohol to recover 860 ml of ethanol, add 1000 ml of soft water to cool and crystallize.

[0024] ③Coarsely filter the crude filtrate after 24 hours of crystallization to obtain coarse crystals of ethyl gallate 289 g. ④Decolorize. Put 289 g of coarse crystals of ethyl gallate into a three-ne...

Embodiment 3

[0028] ①Add 300g of gallic acid, 1500ml of absolute alcohol, and 30g of catalyst concentrated sulfuric acid into a three-necked flask. Connect to the constant pressure dropping funnel (600 g of water-absorbing molecular sieves inside, the molecular sieve is 3A molecular sieve, and must be dried in a drying oven until there is no water before use), the rectification tower (installed with glass filler), and the condenser tube (through cooling water), thermometer (kettle temperature is controlled at 85-90°C, top temperature is controlled at 80-85°C), and heated on a magnetic stirring electric heating mantle, and reacted for 10 hours.

[0029] ② After the reaction, distill the excess alcohol to recover 1300 ml of ethanol, add 1500 ml of soft water to cool and crystallize.

[0030] ③The crude filtrate was crystallized for 24 hours and then coarsely filtered to obtain 434 g of coarse crystals of ethyl gallate

[0031] ④ Decolorization Put 434g of ethyl gallate coarse cryst...

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Abstract

The invention relates to a synthesis method of ethyl gallate. The method comprises the following steps: carrying out esterification on gallic acid, absolute alcohol and sulfuric acid used as raw materials in a reaction kettle, sending water-ethanol mixed steam into a rectification tower directly connected with the reaction kettle to perform separation, controlling the reflux ratio to control the tower top temperature at 80-85 DEG C, returning the distilled ethanol into the reaction kettle to continue reaction, sending the cooled substance (water-ethanol mixture) on the rectification tower bottom into the reaction kettle via a constant-pressure dropping funnel (filled with a water-absorbing 3A molecular sieve) to continue reaction, carrying out esterification reaction for 8-10 hours while controlling the reaction temperature at 85-90 DEG C, distilling to recover the ethanol, adding soft water, cooling to crystallize, carrying out crude centrifugation, decolorizing, carrying out fine filtration, fine crystallization and fine centrifugation to obtain a fine product, and drying to obtain the ethyl gallate. The reaction procedure adopts the rectification tower and molecular sieve for water absorption, so that the reaction time is shortened, the product yield can reach 98.0%, and the ethyl gallate product purity is greater than 99.5%; and no water-carrying agent is needed in the reaction, thereby saving the cost and lowering the unit consumption.

Description

technical field [0001] The invention relates to the field of fine chemicals, and in particular provides a method for synthesizing ethyl gallate. Background technique [0002] Ethyl gallate, whose chemical name is ethyl 3,4,5-trihydroxybenzoate; its molecular formula is C 9 h 10 o 5 ; The structural formula is: [0003] Appearance: white crystalline powder; melting point 149-153 ℃. It is a fine chemical product with a wide range of uses, mainly used in organic synthesis, food, light industry and electronics industry. The traditional synthetic method of ethyl gallate is to use gallic acid and ethanol as raw materials, use concentrated sulfuric acid as catalyst and dehydrating agent, carry out esterification reaction and reclaim ethanol under 100 ℃ and condition, obtain ethyl gallate crude product, and then Washing, recrystallization and decolorization, cooling centrifugation, drying and other processes to obtain the finished product of ethyl gallate. The main disadvan...

Claims

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Application Information

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IPC IPC(8): C07C67/08C07C69/84
CPCC07C67/08
Inventor 罗勇刘林谢龙生
Owner 遵义林源医药化工有限责任公司
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