A kind of method of secondary nitration synthesis 5-nitrobenzimidazolone

A technology of nitrobenzimidazolone and benzimidazolone, which is applied in the field of synthesizing 5-nitrobenzimidazolone, can solve the problems of large product impurity peaks, large environmental pollution, and low safety factor, and achieve stable reaction, The effect of improving product purity and reducing pollution

Active Publication Date: 2021-05-18
SHANDONG HUIHAI PHARMA & CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a method for secondary nitration to synthesize 5-nitrobenzimidazolone, which overcomes the problems of low safety factor, large environmental pollution, large impurity peak and low purity in the prior art.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] A method for secondary nitration to synthesize 5-nitrobenzimidazolone. The steps are: add 60g of benzimidazolone dry product and 347g of nitric acid mother liquor (9% nitric acid mass concentration) to a 1L reactor, and control the temperature at 45 Between -70°C, keep warm for 1 hour. After the material in the reaction kettle turns green, transfer the material liquid to 200g of dilute nitric acid prepared in advance through the metering pump (the mass concentration of nitric acid is 30.58%), and the temperature is controlled at 60-70°C In between, heat preservation for 1 hour, the heat preservation reaction is completed, and the temperature is lowered to 50° C. for hot suction filtration. The filtrate, namely the nitric acid mother liquor, is applied mechanically to the next batch of nitration reactions. After testing, the molar yield was 99.5%, and the purity was 99.33%.

Embodiment 2

[0030] A method for secondary nitration to synthesize 5-nitrobenzimidazolone, the steps are: add 60g of benzimidazolone dry product and 347g of nitric acid mother liquor (9% nitric acid mass concentration) to a 1L reactor, and control the temperature at 25 Between -45°C, keep warm for 1 hour. After the material in the reaction kettle turns green, transfer the material liquid into 200g of dilute nitric acid prepared in advance through the metering pump (the mass concentration of nitric acid is 30.58%), and the temperature is controlled at 60-70°C In between, heat preservation for 1 hour, the heat preservation reaction is completed, and the temperature is lowered to 50° C. for hot suction filtration. The filtrate, namely the nitric acid mother liquor, is applied mechanically to the next batch of nitration reactions. After testing, the molar yield was 99.1%, and the purity was 98.62%.

Embodiment 3

[0032] A method for secondary nitration to synthesize 5-nitrobenzimidazolone. The steps are: add 60g of benzimidazolone dry product and 347g of nitric acid mother liquor (9% nitric acid mass concentration) to a 1L reactor, and control the temperature at 45 Between -70°C, keep warm for 1 hour. After the material in the reaction kettle turns green, transfer the material liquid to 200g of dilute nitric acid prepared in advance through the metering pump (the mass concentration of nitric acid is 25%), and the temperature is controlled at 60-70°C In between, heat preservation for 1 hour, the heat preservation reaction is completed, and the temperature is lowered to 50° C. for hot suction filtration. The filtrate, namely the nitric acid mother liquor, is applied mechanically to the next batch of nitration reactions. After testing, the molar yield was 98.45%, and the purity was 97.89%.

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Abstract

The invention discloses a method for synthesizing 5-nitrobenzimidazolone by secondary nitration. The steps are as follows: put benzimidazolone into a primary nitration kettle, add nitration mother liquor into the primary nitration kettle to start stirring, and control Adjust the reaction temperature and reaction time to carry out the initial nitration reaction. Then prepare the acid solution in the secondary nitration kettle, and after the heat preservation is over, transfer the primary nitration material liquid into the secondary nitration reaction kettle through the material liquid pump to carry out the nitration reaction; carry out the second heat preservation, and finally pass the solid-liquid separation 5‑nitrobenzimidazolone is obtained. The invention reduces the risk of nitrification by improving the nitrification method, not only reduces the labor intensity of mass production, improves product quality, but also solves the problems of safety and environmental protection.

Description

technical field [0001] The invention relates to the field of fine chemical technology, in particular to a method for synthesizing 5-nitrobenzimidazolone. Background technique [0002] 5-Nitrobenzimidazolone is a yellow-green powder with a molecular weight of 179 and a melting point of 316-318°C. It is mainly used as a raw material for the synthesis of pigment yellow and pigment orange. [0003] At present, the method of large-scale production of 5-nitrobenzimidazolone at home and abroad is mainly based on o-phenylenediamine and urea as raw materials, which are prepared through nitration reaction. The nitrification reaction uses the traditional dropping method, which is characterized by large heat release, viscous material, partial over-reaction, and is difficult to control. The 5-nitrobenzimidazolone produced has low purity and low safety factor, which is a dangerous process stipulated by the state. The nitrification reaction releases a lot of heat, which intensifies the ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D235/26
CPCC07D235/26
Inventor 侯利国王磊王明飞张国辉王乐强李华振
Owner SHANDONG HUIHAI PHARMA & CHEM
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