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A kind of preparation method of 2-methylimidazole

A technology of methylimidazole and acetaldehyde, which is applied in the field of preparation of 2-methylimidazole, can solve the problems of high raw material cost, high reaction temperature, and affecting system balance, so as to reduce production cost, increase product yield, and shorten crystallization the effect of time

Active Publication Date: 2020-11-06
HUBEI HONGYUAN PHARMA
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  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

The nitrile amine method has been rarely used because of its high cost, high reaction temperature, and strict requirements on reaction equipment; the glyoxal method has higher requirements for glyoxal, and the glyoxal used in China is mainly imported. The cost of raw materials is high, and the concentration of glyoxal has a great influence on the yield. In addition, the purity of the 2-methylimidazole obtained by this method is relatively low; there is a low yield in the process of directly producing glyoxal by oxidation of acetaldehyde nitric acid. problem, and the solubility of the intermediate generated by the reaction of glyoxal, acetaldehyde and ammonium bicarbonate is very small, which affects the balance of the system and will make the yield of 2-methylimidazole low

Method used

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preparation example Construction

[0010] The present embodiment provides a kind of preparation method of 2-methylimidazole, comprises the steps:

[0011] (1) Reduce the temperature of the reactor to below 18°C, and put 685-777 parts of ammonia water with a mass concentration of 22-23% (in pure quantity) and 100-150 parts of ammonium bicarbonate into the reactor in parts by weight In, stir to mix evenly;

[0012] If the amount of ammonium bicarbonate instead of ammonia water is too much, it will increase the production cost, and the discharge of tail gas will also increase, which is also not conducive to the subsequent concentration of 2-methylimidazole; if the amount of ammonium bicarbonate instead of ammonia water is too small, it will affect 2 - The color of the finished methylimidazole product and the stability of the crystal structure, so the selected ammonia water is 685-777 parts by weight (converted to pure quantity), and the weight ratio of ammonium bicarbonate is 100-150 parts;

[0013] (2) Add 840~9...

Embodiment 1

[0021] (1) Reduce the temperature of the reactor to below 18°C, put 685 kg of ammonia water with a mass concentration of 22% into the reactor, and 140 kg of ammonium bicarbonate, and stir and mix evenly;

[0022] (2) Add 884 kg of acetaldehyde with a mass concentration of 48.5% to the reactor, stir evenly, raise the temperature of the reactor to 18°C, and react at this temperature for 3 hours. Continue to keep warm for 0.3h at ℃;

[0023] (3) Add 1220 kg of glyoxal with a mass concentration of 41% to the reactor, and further raise the temperature of the reactor to 40°C, and after 3 hours of reaction, raise the temperature of the reactor to 45°C ℃, keep warm for 0.8h;

[0024] (4) After the heat preservation reaction in step (3) is completed, the reaction solution is concentrated into a saturated solution under the conditions of temperature lower than 67°C, steam pressure ≥ 0.2Mpa, circulating water pressure ≥ 0.2Mpa, and vacuum degree ≤ -0.08Mpa , transfer the saturated solu...

Embodiment 2

[0026] (1) Reduce the temperature of the reactor to below 18°C, put 738 kg of ammonia water with a mass concentration of 22% into the reactor, and 150 kg of ammonium bicarbonate, and stir and mix evenly;

[0027] (2) Add 928 kg of acetaldehyde with a mass concentration of 48% to the reactor, stir evenly, raise the temperature of the reactor to 20°C, and react at this temperature for 3.5 hours. Continue the heat preservation reaction at 20°C for 0.5h;

[0028] (3) Add 1220 kg of glyoxal with a mass concentration of 40% to the reactor, and further raise the temperature of the reactor to 42°C, and after 4 hours of reaction, raise the temperature of the reactor to 46 ℃, keep warm for 1h;

[0029] (4) After the heat preservation reaction in step (3) is completed, the reaction solution is concentrated into a saturated solution under the conditions of temperature lower than 67°C, steam pressure ≥ 0.2Mpa, circulating water pressure ≥ 0.2Mpa, and vacuum degree ≤ -0.08Mpa , transfer t...

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Abstract

The invention discloses a preparation method of 2-methylimidazole. The preparation method comprises the following steps: uniformly mixing ammonia water and ammonium hydrogen carbonate at 18 DEG C below; heating to 18-22 DEG C, adding acetaldehyde into a mixture solution obtained in the step 1 for reacting for 3-4 hours, and then performing a heat-preservation reaction for 0.3-0.8 hour; then heating to 40-44 DEG C, adding glyoxal to a mixture solution obtained in the step 2 for reacting for 3-5 hours, and then after the reaction, heating to 45-47 DEG C for performing a heat-preservation reaction for 0.8-1.2 hours; and finally, concentrating a reaction solution to a saturated solution, and adjusting the pH value of the saturated solution to 7-9 for crystalizing, and performing centrifugal separation and subsequent treatment to obtain 2-methylimidazole. The method provided by the invention improves the reaction yield and purity and lowers the production cost of the final product by adjusting the reaction raw materials, the reaction process and the parameters.

Description

technical field [0001] The invention belongs to the technical field of chemical synthesis, and in particular relates to a preparation method of 2-methylimidazole. Background technique [0002] The molecular formula of 2-methylimidazole is C4H6N2, the relative molecular weight is 82.11, the appearance is light yellow crystal, the melting point is 142~143°C, the boiling point is 267°C, it is soluble in water and alcohol, but insoluble in cold benzene. 2-Methylimidazole is an intermediate in the synthesis of anti-anaerobe infection drugs such as metronidazole, tinidazole, ornidazole, and is also widely used as a curing agent for epoxy resins. At present, the synthesis methods of 2-methylimidazole mainly include the following: (1) nitrile amine method: ethylenediamine is mixed with acetonitrile, and sulfur is used as a catalyst to react under certain conditions, then add zinc powder for desulfurization, and then add Raney nickel is dehydrogenated at high temperature, and finall...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D233/58
CPCC07D233/58
Inventor 方耀徐双喜邓支华喻莎莎晏浩哲潘云渠童武黄佐周拥军陈申邓洋汪宏福
Owner HUBEI HONGYUAN PHARMA
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