CN107365273B - Production method for synthesizing 5-nitrobenzimidazole ketone by one-pot method - Google Patents
Production method for synthesizing 5-nitrobenzimidazole ketone by one-pot method Download PDFInfo
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- CN107365273B CN107365273B CN201710685730.3A CN201710685730A CN107365273B CN 107365273 B CN107365273 B CN 107365273B CN 201710685730 A CN201710685730 A CN 201710685730A CN 107365273 B CN107365273 B CN 107365273B
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- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D235/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, condensed with other rings
- C07D235/02—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, condensed with other rings condensed with carbocyclic rings or ring systems
- C07D235/04—Benzimidazoles; Hydrogenated benzimidazoles
- C07D235/24—Benzimidazoles; Hydrogenated benzimidazoles with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached in position 2
- C07D235/26—Oxygen atoms
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Abstract
The invention provides a production method for synthesizing 5-nitrobenzimidazole ketone by a one-pot method, which comprises the following steps: adding o-phenylenediamine and urea into a chlorobenzene solvent in a reaction kettle for condensation reaction to obtain benzimidazolone; after the condensation reaction is finished, cooling to 80-90 ℃, then supplementing a chlorobenzene solvent into the reaction kettle, and simultaneously adjusting the pH value to be between 5 and 7; continuously reducing the temperature of the reaction system to 50-60 ℃, and then directly dripping nitric acid solution into the reaction kettle for nitration reaction; after the reaction is finished, cooling to room temperature, and separating out chlorobenzene mother liquor from the reaction liquid to obtain the product 5-nitrobenzimidazole ketone. The invention combines the two-step reaction operation of condensation and nitration in one reactor, does not need filtration and separation, and shortens the process flow; the recycled chlorobenzene containing nitric acid is used for adjusting the solution after condensation, so that raw materials are saved, the yield and quality of products are improved, and the production cost is reduced.
Description
Technical Field
The invention relates to the field of chemical product preparation processes, and particularly relates to a production method for synthesizing 5-nitrobenzimidazole ketone by a one-pot method.
Background
The current production process of 5-nitrobenzimidazole ketone is as follows: firstly, generating benzimidazolone through condensation reaction in a solvent, then filtering and separating to remove the solvent, transferring the benzimidazolone into a nitration procedure to carry out nitration reaction, and carrying out nitration reaction in a water phase by adopting a mixed acid process; the defects of the process steps are that the first condensation reaction needs filtration and separation, the process flow is long, the production period is long, the equipment investment is large, and the second condensation reaction and the nitration reaction have different solvents and cannot be recycled, so that the waste of resources is caused; the trinitration reaction adopts a water phase reaction to generate a large amount of acid-containing wastewater, thereby improving the pressure of subsequent wastewater treatment and greatly improving the production cost.
Disclosure of Invention
Aiming at the technical defects, the invention provides the production method for synthesizing the 5-nitrobenzimidazole ketone by the one-pot method, which has the advantages of simple process, convenient operation and low cost, and can greatly improve the yield and the purity of the 5-nitrobenzimidazole ketone.
The technical scheme of the invention is as follows:
the production method for synthesizing 5-nitrobenzimidazole ketone by one-pot method comprises the following steps:
(1) adding raw materials of o-phenylenediamine and urea into a chlorobenzene solvent according to the molar ratio of 1: 1.05-1.20 in a reaction kettle to form a reaction system, and carrying out condensation reaction to obtain benzimidazolone; the condensation reaction is controlled at the temperature of 100-120 ℃ for 4-6 h; the dosage of the chlorobenzene solvent is 3-4 times of the weight of the o-phenylenediamine as the raw material;
(2) after the condensation reaction is finished, cooling the reaction system to 80-90 ℃, and then supplementing a chlorobenzene solvent into the reaction kettle until the total weight of the chlorobenzene solvent is 6-8 times of the weight of the o-phenylenediamine; simultaneously adjusting the pH value of the reaction system to be between 5 and 7;
(3) continuously reducing the temperature of the reaction system to 50-60 ℃, and then directly dripping nitric acid solution into the reaction kettle for nitration reaction, wherein the nitration reaction time is 0.5-5 h; the molar ratio of the nitric acid to the raw material o-phenylenediamine is 3:1-4: 1;
(4) after the reaction is finished, cooling the reaction system to room temperature, and separating out chlorobenzene mother liquor from the reaction liquid to obtain the product 5-nitrobenzimidazole ketone.
Further preferably, the additional chlorobenzene solvent in the step (2) is chlorobenzene mother liquor separated in the previous step (4).
Further preferably, the nitric acid solution is a nitric acid solution with a mass concentration of 65-67%.
Further preferably, a part of the chlorobenzene mother liquor obtained in the step (4) is separated and recovered by distillation, and is used as a solvent for the condensation reaction in the step (1).
Further preferably, the separation in the step (4) adopts a filtration separation mode
Compared with the prior art, the invention has the following advantages: the invention combines the two-step reaction operation of condensation and nitration in one reactor, does not need filtration and separation, shortens the process flow and reduces the equipment; the recycled chlorobenzene containing nitric acid is used for adjusting the solution after condensation, so that the raw materials are saved; the nitration reaction adopts a solvent phase to carry out reaction, replaces a mixed acid nitration process, avoids producing a large amount of acid-containing wastewater, reduces the production cost, and has the product yield of more than 97.4 percent and the product content of more than 98.5 percent.
Detailed Description
The present invention is described in detail below by way of specific examples, but the use and purpose of these exemplary embodiments are merely to exemplify the present invention, and do not set forth any limitation on the actual scope of the present invention in any form, and the scope of the present invention is not limited thereto.
Example 1
The production method for synthesizing 5-nitrobenzimidazole ketone by one-pot method comprises the following steps:
1. adding o-phenylenediamine and urea into a chlorobenzene solvent according to the molar ratio of 1:1.05 in a reaction kettle to form a reaction system, and carrying out condensation reaction to obtain benzimidazolone; the condensation reaction is controlled at 100 ℃ for 6 h; the weight of the chlorinated benzene solvent is 3 times of the total weight of the o-phenylenediamine.
2. After the condensation reaction is finished, cooling the reaction system to 90 ℃, then supplementing a chlorobenzene solvent into the reaction kettle until the total weight of the chlorobenzene solvent is 6 times of the addition amount of the o-phenylenediamine, and simultaneously adjusting the pH value of the reaction system to be 5.
3. Continuously reducing the temperature of the reaction system to 60 ℃, and then directly dropwise adding a nitric acid solution with the mass concentration of 65-67% into the reaction kettle to carry out nitration reaction, wherein the nitration reaction time is 1 h; the molar ratio of the nitric acid to the raw material o-phenylenediamine is 3: 1.
4. After the reaction is finished, cooling the reaction system to room temperature, and separating out chlorobenzene mother liquor from the reaction liquid to obtain the product 5-nitrobenzimidazole ketone.
Example 2
The production method for synthesizing 5-nitrobenzimidazole ketone by one-pot method comprises the following steps:
1. adding o-phenylenediamine and urea into a chlorobenzene solvent according to the molar ratio of 1:1.2 in a reaction kettle to form a reaction system, and carrying out condensation reaction to obtain benzimidazolone; the condensation reaction is controlled at 120 ℃ for 4 hours; the weight of the chlorinated benzene solvent is 4 times of the total weight of the o-phenylenediamine and the urea.
2. After the condensation reaction is finished, cooling the reaction system to 80 ℃, adding a chlorobenzene solvent into the reaction kettle until the total weight of the chlorobenzene solvent is 8 times of the addition amount of the o-phenylenediamine, and adjusting the pH value of the reaction system to be 7.
3. Continuously reducing the temperature of the reaction system to 50 ℃, and then directly dropwise adding a nitric acid solution with the mass concentration of 65-67% into the reaction kettle to carry out nitration reaction, wherein the nitration reaction time is 5 hours; the molar ratio of the nitric acid to the raw material o-phenylenediamine is 4: 1.
4. After the reaction is finished, cooling the reaction system to room temperature, and separating out chlorobenzene mother liquor from the reaction liquid to obtain the product 5-nitrobenzimidazole ketone.
Example 3
The production method for synthesizing 5-nitrobenzimidazole ketone by one-pot method comprises the following steps:
1. adding o-phenylenediamine and urea into a chlorobenzene solvent according to the molar ratio of 1:1.1 in a reaction kettle to form a reaction system, and carrying out condensation reaction to obtain benzimidazolone; the condensation reaction is controlled at the temperature of 110 ℃ for 5 hours; the weight of the chlorinated benzene solvent is 3.5 times of the total weight of the o-phenylenediamine and the urea.
2. After the condensation reaction is finished, cooling the reaction system to 85 ℃, adding a chlorobenzene solvent into the reaction kettle until the total weight of the chlorobenzene solvent is 7 times of the addition amount of the o-phenylenediamine, and adjusting the pH value of the reaction system to be 6.
3. Continuously reducing the temperature of the reaction system to 55 ℃, and then directly dropwise adding a nitric acid solution with the mass concentration of 65-67% into the reaction kettle to carry out nitration reaction, wherein the nitration reaction time is 3 h; the molar ratio of nitric acid to the raw material o-phenylenediamine is 3.5: 1.
4. After the reaction is finished, cooling the reaction system to room temperature, and separating out chlorobenzene mother liquor from the reaction liquid to obtain the product 5-nitrobenzimidazole ketone.
Example 4
The other process steps of example 1 were kept unchanged and only the additional chlorobenzene solvent in step 2 was changed to the additional chlorobenzene mother liquor obtained in example 1.
Example 5
The other process steps of example 2 were kept unchanged and only the additional chlorobenzene solvent in step 2 was changed to the additional chlorobenzene mother liquor obtained in example 2.
Example 6
The other process steps of example 3 were kept unchanged and only the additional chlorobenzene solvent in step 2 was changed to the additional chlorobenzene mother liquor obtained in example 3.
Comparative example 1
The other process steps of example 3 were kept unchanged, only step 2 was deleted, i.e. the condensation reaction was followed directly to the nitration reaction.
Comparative example 2
The other process steps of example 6 were kept unchanged, only step 2 was deleted, i.e. the condensation reaction was followed directly to the nitration reaction.
The 5-nitrobenzimidazolone obtained by the production methods of the above examples 1 to 6 and comparative examples 1 to 2 showed the following results:
| examples | Yield of | Content (wt.) |
| Example 1 | 97.4 | 98.6 |
| Example 2 | 97.5 | 98.5 |
| Example 3 | 98.4 | 99.2 |
| Example 4 | 97.8 | 98.7 |
| Example 5 | 97.7 | 98.8 |
| Example 6 | 98.8 | 99.5 |
| Comparative example 1 | 82.1 | 82.5 |
| Comparative example 2 | 85.4 | 83.2 |
As can be seen from the data in the table above: the chlorobenzene solvent supplemented in the step 2 is replaced by the chlorobenzene mother liquor obtained in the previous batch, and the yield and the content of the final product are both slightly improved after the chlorobenzene mother liquor is reused by comparing the embodiments 1-3 and 4-6; by comparing the examples 3 and 6 with the comparative examples 1 and 2, the step (2) is introduced after the condensation reaction, and then the nitration reaction is carried out, so that the process design can greatly improve the yield and the content of the product; overall, the best technical result is obtained in example 6, i.e. the highest yields and contents of product are obtained by the production process.
The above description is only exemplary of the present invention, and those skilled in the art may modify the present invention or modify the present invention into equivalent technical solutions by using the technical solutions described above. Therefore, any simple modifications or equivalent substitutions made in accordance with the technical solution of the present invention are within the scope of the claims of the present invention.
Claims (5)
1. A production method for synthesizing 5-nitrobenzimidazole ketone by a one-pot method is characterized by comprising the following steps:
(1) adding raw materials of o-phenylenediamine and urea into a chlorobenzene solvent according to the molar ratio of 1: 1.05-1.20 in a reaction kettle to form a reaction system, and carrying out condensation reaction to obtain benzimidazolone; the condensation reaction is controlled at the temperature of 100-120 ℃ for 4-6 h; the dosage of the chlorobenzene solvent is 3-4 times of the weight of the o-phenylenediamine as the raw material;
(2) after the condensation reaction is finished, cooling the reaction system to 80-90 ℃, and then supplementing a chlorobenzene solvent into the reaction kettle until the total weight of the chlorobenzene solvent is 6-8 times of the weight of the o-phenylenediamine; simultaneously adjusting the pH value of the reaction system to be between 5 and 7;
(3) continuously reducing the temperature of the reaction system to 50-60 ℃, and then directly dripping nitric acid solution into the reaction kettle for nitration reaction, wherein the nitration reaction time is 0.5-5 h; the molar ratio of the nitric acid to the raw material o-phenylenediamine is 3:1-4: 1;
(4) after the reaction is finished, cooling the reaction system to room temperature, and separating out chlorobenzene mother liquor from the reaction liquid to obtain the product 5-nitrobenzimidazole ketone.
2. The production method for synthesizing 5-nitrobenzimidazolone according to the one-pot method of claim 1, wherein the additional chlorobenzene solvent in the step (2) is chlorobenzene mother liquor separated from the previous batch of the step (4).
3. The production method for synthesizing 5-nitrobenzimidazolone according to the one-pot method of claim 1, wherein the nitric acid solution is a nitric acid solution with a mass concentration of 65-67%.
4. The production method for synthesizing 5-nitrobenzimidazole ketone by the one-pot method according to claim 1, which is characterized in that a part of the chlorobenzene mother liquor obtained in the step (4) is separated by distillation to recover chlorobenzene for use in the condensation reaction in the step (1) as a solvent.
5. The production method for synthesizing 5-nitrobenzimidazole ketone by the one-pot method according to claim 1, wherein the separation in the step (4) is implemented by filtration and separation.
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| CN108329273B (en) * | 2017-12-21 | 2021-05-18 | 山东汇海医药化工有限公司 | Method for synthesizing 5-nitrobenzimidazole ketone by secondary nitration |
| CN108101850B (en) * | 2017-12-21 | 2021-12-07 | 山东汇海医药化工有限公司 | Method for improving quality of 5-acetoacetylaminobenzimidazolone |
| CN109320462A (en) * | 2018-11-23 | 2019-02-12 | 山东汇海医药化工有限公司 | A kind of method of o-phenylenediamine impurity in reduction 5-Nitro-2-benzimidazolinone |
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