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Method for preparing 2,3,5,6-tetramethylpyrazine

A technology of tetramethylpyrazine and industrial phosphoric acid, applied in the chemical field, can solve the problems of complex production process, low yield and high raw material price, and achieve the effects of safe process operation, easy availability of raw materials and cheap raw materials

Pending Publication Date: 2018-04-06
SHANDONG JITIAN AROMA CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above synthetic methods have disadvantages such as low yield, complex production process, or high raw material prices.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] A preparation method of 2,3,5,6-tetramethylpyrazine, using industrial phosphoric acid, ammonia, and acetoin as raw materials, one-pot synthesis of 2,3,5,6-tetramethylpyrazine, specifically Include the following steps:

[0019] 1) Take a 1000ml three-neck flask, install a stirrer, thermometer, ammonia gas equipment and heating mantle;

[0020] 2) Add 120g (1.04mol) of industrial phosphoric acid (85%) and 600g of process water into the three-necked flask, and stir evenly after adding;

[0021] 3) Control the temperature at 20~40°C, pass ammonia gas into the bottle, and stop when the system is measured to pH﹦7.8~8.2;

[0022] 4) Control the temperature at 30~40°C, add 60g (0.68mol) of acetoin dropwise, and finish dropping for about 30 minutes, then keep it warm for 2 hours;

[0023] 5) Raise the temperature to 90~100°C and react for 1 hour;

[0024] 6) Heating distillation, 100 ℃ normal distillate, when the temperature rises to 103 ℃, the distillation is completed, and ...

Embodiment 2

[0029] A preparation method of 2,3,5,6-tetramethylpyrazine, using industrial phosphoric acid, ammonia, and acetoin as raw materials, one-pot synthesis of 2,3,5,6-tetramethylpyrazine, specifically Include the following steps:

[0030] 1) Add 120kg (1.04mol) of industrial phosphoric acid (85%) and 600kg of process water to the reactor, and stir evenly after adding;

[0031] 2) Control the temperature at 20-40°C, pass ammonia gas into the bottle, and stop when the system is measured to pH﹦7.8-8.2;

[0032] 4) Control the temperature at 30~40°C, add 60kg (0.68mol) of acetoin dropwise for about 30 minutes, and keep it warm for 2 hours;

[0033] 5) Raise the temperature to 90~100°C and react for 1 hour;

[0034] 6) Distillation by heating, the distillate is normally produced at 100°C, when the temperature rises to 103°C, the distillation is completed, and 350kg of distillate is obtained;

[0035] 7) Add a small amount of phosphoric acid to the distillate to adjust the pH﹦6~7, the...

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Abstract

The invention discloses a method for preparing 2,3,5,6-tetramethylpyrazine. The method comprises the following steps: adding industrial phosphoric acid and process water into a three-necked flask having a volume of 1000ml, and uniformly stirring; controlling temperature to be 20-40 DEG C, introducing ammonia gas into the flask until the pH of the system is 7.8-8.2; controlling the temperature to be 30-40 DEG C, dropwise adding acetoin for about 30 minutes, and insulating to react for 2 hours; heating to 90-100 DEG C to react for 1 hour; heating and distilling to obtain fraction at 100 DEG C, and completing distillation when the temperature is 103 DEG C to obtain distillate; adding a small amount of phosphoric acid into the distillate to regulate the pH to be 6-7, cooling to 0-5 DEG C, standing for 4 hours or more, and extracting and filtering the mixture to obtain a crude product; recrystallizing the crude product with water, separating to obtain a wet product, and drying in vacuum toobtain the product. The 2,3,5,6-tetramethylpyrazine has the benefcial effects that the raw materials are low in price and easily available, the reaction stock solution can be recycled, the process operation is safe and environmentally friendly, the product has relatively good quality and relatively low cost and is suitable for large-scale production.

Description

Technical field: [0001] The invention specifically relates to a preparation method of 2,3,5,6-tetramethylpyrazine, which belongs to the technical field of chemical industry. Background technique: [0002] At present, there are two types of 2,3,5,6-tetramethylpyrazine synthesis methods at home and abroad, one is biosynthesis, which mainly uses glucose as raw material and is a natural product obtained by microbial fermentation; the other is chemical synthesis Most of them are synthesized from 2,3-butanedione, 2,3-butanediamine or butanone and ethyl nitrite, or synthesized from acetoin and ammonium acetate in ethanol. The above synthetic methods have disadvantages such as low yield, complex production process, or high raw material prices. Invention content: [0003] In view of this, the present invention provides a kind of 2,3,5,6-tetramethylpyridine that is cheap and easy to obtain, the reaction mother liquor can be recycled, the process operation is safe, green, environmen...

Claims

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Application Information

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IPC IPC(8): C07D241/12
CPCC07D241/12
Inventor 杨亮杨位祥
Owner SHANDONG JITIAN AROMA CHEM CO LTD
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