CN113121447A - Synthetic method for preparing 5-aminobenzimidazole ketone - Google Patents
Synthetic method for preparing 5-aminobenzimidazole ketone Download PDFInfo
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- 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
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Abstract
The invention discloses a synthetic method for preparing 5-aminobenzimidazole ketone (TM), which comprises the following steps of firstly carrying out diazotization reaction on aniline to prepare aniline diazonium salt; and (2) coupling aniline diazonium salt with o-phenylenediamine to generate an azo compound, reacting the azo compound with urea under the catalysis of concentrated sulfuric acid to generate an azobenzimidazolone compound, and carrying out hydrogenation reduction reaction on the azobenzimidazolone compound to obtain the target compound 5-aminobenzimidazolone. The method has the advantages of simple process, high selectivity, high product yield, utilization of all the used reactants and high atom economy. Avoids the use of a nitration reagent, namely concentrated nitric acid, greatly reduces the generation of salt in the wastewater and the waste water, and is a green production process. In addition, the hydrocracking reduction operation is simple, other iron mud such as iron powder reduction is not generated, waste residues are basically avoided, the quality of finished products is obviously improved, filter-pressing rinsing water can be repeatedly used for more than one time, the cost is reduced, and the environmental pollution is reduced.
Description
Technical Field
The invention belongs to the field of organic chemical intermediates, and particularly relates to a synthetic method for preparing 5-aminobenzimidazole ketone.
Background
Benzimidazolone pigments belong to the class of high-performance organic pigments which were first developed successfully by the German husky company in the sixties of the last century, have very brilliant colors and high tinctorial strength. Due to the existence of the cyclic amide group in the molecule, the polarity of the molecule is increased, a hydrogen bond can be formed, the aggregation state of the molecule is changed, and the pigment has excellent performance. 5-aminobenzimidazole ketone (TM) is a key intermediate for synthesizing a high-performance pigment variety, namely benzimidazolone pigment, with the rapid development of the industries such as plastics, coatings, printing ink and the like, the demand for 5-aminobenzimidazole ketone is rapidly increased at home and abroad, and a large amount of waste water and waste residues are generated in the production process at home, so that the production process is not beneficial to environmental protection. Therefore, the search for a route for synthesizing the 5-aminobenzimidazole ketone, which has the advantages of low cost, good product quality, less three wastes and environmental protection, becomes the key for developing and synthesizing the benzimidazolone organic pigment.
The 5-aminobenzimidazole ketone (TM) is a white to light yellow crystal, and the production processes and synthesis methods at home and abroad at present are as follows:
one route is that o-phenylenediamine (I) and urea are used as raw materials, and the reaction process is carried out according to the following steps:
o-phenylenediamine (I) and urea generate benzimidazolone (II) in a solid phase or a solvent phase, the benzimidazolone (II) generates 5-nitrobenzimidazolone (III) through nitration reaction, and the 5-nitrobenzimidazolone (III) is reduced by iron powder, hydrazine hydrate, catalytic hydrogenation, electrochemical reduction and other methods to prepare the 5-aminobenzimidazolone (TM). (Chinese patent CN101307023A, CN 104130194).
The disadvantage of this route is that benzimidazolone and chlorobenzene are subjected to nitration in concentrated nitric acid, which has the disadvantage that chlorobenzene with high toxicity is used in nitration, and a large amount of three wastes are generated when concentrated nitric acid is used for nitration.
Shenyongjia, written "organic pigment-variety and application", chapter 16, page 174, describes a nitration route of benzimidazolone in concentrated nitric acid and concentrated sulfuric acid, which mentions that although the synthesis method is simple and the raw materials are easily available, the disadvantage is that the benzimidazolone is easy to generate dinitro substance during nitration, and the dinitro substance is not easy to remove, and the reaction by-product is difficult to remove, which affects the quality of the final product. The concentrated nitric acid and the concentrated sulfuric acid used in the reaction also generate a large amount of waste water, and the environmental pollution is large.
In another route, 2, 4-dinitrochlorobenzene (IV) is used as a raw material, 5-nitrobenzimidazolone (III) is prepared through the following route, and the 5-nitrobenzimidazolone (III) is reduced into 5-aminobenzimidazolone (TM). However, the preparation of the raw material 2, 4-dinitrochlorobenzene (IV) is also subjected to nitration reaction by concentrated nitric acid and concentrated sulfuric acid, and three wastes generated by the nitration reaction are high, so that the method is not environment-friendly. (Zhouculong, organic pigment chemistry and technology, third edition, page 44.)
In conclusion, in the two common routes, concentrated nitric acid or concentrated nitric acid and concentrated sulfuric acid are used for nitration in the nitration process, so that the water consumption and the energy consumption are high, the three wastes pollution is high, and byproducts are difficult to remove.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a synthetic method for preparing 5-aminobenzimidazole ketone, which has simple technical process and high product yield. The aniline used in the reaction can be repeatedly used, the atom economy is high, the reaction does not contain a nitration process, the concentrated nitric acid is not used, and the three-waste pollution is less.
In order to achieve the purpose, the invention adopts the following technical scheme that the synthesis method for preparing the 5-aminobenzimidazole ketone (TM) mainly comprises the following steps:
(1) diazotization of aniline and coupling with o-phenylenediamine: firstly, carrying out diazotization reaction on aniline to prepare aniline diazonium salt; the aniline diazonium salt is coupled with o-phenylenediamine (I) to form azo compound (V)
Under the temperature condition of-5 to 5 ℃, a certain amount of sodium nitrite is added into hydrochloric acid solution of aniline, sulfamic acid is added for reaction, and aqueous solution of aniline diazonium salt is prepared. Dropwise adding the diazo solution into an o-phenylenediamine solution at a pH of 5 to 10 to carry out a coupling reaction at a temperature of-6 ℃ to 30 ℃ (preferably-4 ℃ to 5 ℃) to obtain the azo compound (V);
wherein the molar ratio of the aniline to the o-phenylenediamine is 1: (0.9-1.1).
(2) Preparation of the azobenzimidazolone compound (VI): and (3) reacting the azo compound (V) with urea under the catalysis of concentrated sulfuric acid to generate an azobenzimidazolone compound (VI).
Mixing an azo compound (V) and urea in a molar ratio of 1: 0.99-1.4, adding a certain amount of water into a condensation reaction kettle, preserving the temperature for 2-3 hours at 90-120 ℃, slowly adding concentrated sulfuric acid in the process of preserving the temperature, controlling the pH value to be 6-7, and drying the obtained material to obtain the azobenzimidazolone compound (VI).
(3) Preparation of 5-aminobenzimidazole ketone (TM): and (3) carrying out hydrogenation reduction reaction on the azo benzimidazolone compound (VI) to obtain a target compound 5-aminobenzimidazole ketone (TM).
Placing azobenzimidazolone compound (VI), a transition metal catalyst (such as palladium carbon, Raney nickel catalyst) and ethanol (or methanol) in an autoclave, replacing for 5 times by hydrogen, raising the temperature to the reaction temperature, introducing hydrogen into the autoclave at the pressure of 0.5-3MPa (preferably 1-3MPa), keeping for 1-5 hours at 20-100 ℃ (preferably 40-90 ℃), filtering out the catalyst from the reaction solution (recovering the catalyst), concentrating the filtrate (recovering the solvent and aniline), performing suction filtration, washing with water, and drying the filter cake in vacuum to obtain the 5-aminobenzimidazolone with high purity and yield.
The raw materials and reagents involved in the invention are all commercial industrial-grade chemical products: 95-99% of aniline, 95-99.5% of o-phenylenediamine, 40-55% of urea, 98% of concentrated sulfuric acid, 30-34% of hydrochloric acid and 30-32% of liquid caustic soda.
The aniline generated in the reaction can be recycled, so that the pollution is reduced, the cost is reduced, and the atom economy of the invention is greatly improved.
The invention has the beneficial effects that:
the synthesis method for preparing 5-aminobenzimidazole ketone provided by the invention has the advantages of simple process, high selectivity and high product yield, all the used reactants are utilized, and the atom economy is very high. Compared with the existing synthetic route of 5-aminobenzimidazole ketone, the method avoids the use of a nitration reagent, namely concentrated nitric acid, greatly reduces the generation of salt in wastewater and waste water, and is a green production process. In addition, the hydrocracking reduction operation is simple, other iron mud such as iron powder reduction is not generated, waste residues are basically avoided, the quality of finished products is obviously improved, filter-pressing rinsing water can be repeatedly used for more than one time, the cost is reduced, and the environmental pollution is reduced.
Detailed Description
The present invention will be described in detail below by way of examples. Although the present invention has been described with reference to specific examples, it will be apparent to one skilled in the art that various changes in the derivatives, analogs, etc. may be made without departing from the spirit and scope of the invention.
The structure of the 5-aminobenzimidazole compounds prepared according to the invention has been confirmed by different analytical methods, such as nuclear magnetic resonance, mass spectrometry. The content of the reaction product was determined by High Performance Liquid Chromatography (HPLC).
Example 1
Diazotization of aniline and coupling with o-phenylenediamine
A500 mL beaker was charged with 50mL of water, 37.5mL (0.45mol) of concentrated hydrochloric acid and 14g (0.15mol) of aniline, and 150g of crushed ice was added. Under stirring, 30% sodium nitrite solution 37.0g is dripped into the mixture for 20 minutes at 0-5 ℃, the mixture reacts for 30 minutes at 0-5 ℃, a small amount of sulfamic acid is added until the sodium nitrite is not excessive, and the mixture is filtered to obtain bright yellow clear aniline diazo liquid.
17.3g (0.16mol) of o-phenylenediamine is dissolved in 500g of hot water, hydrochloric acid is added to adjust the pH value to 6-7, the temperature is adjusted to-4 ℃, prepared diazo liquid is started to be dripped into the o-phenylenediamine solution for unidirectional coupling, coupling components are slightly excessive when the coupling is finished, the mixture is continuously stirred for 30min, the temperature is raised to 95 ℃, the reaction is carried out for 3 hours, the mixture is filtered, washed with water and dried to obtain 29.2g of yellow solid (azo compound V), the yield is 89.3 percent, and the purity is 97.2 percent. EI-MS M/z [ M ]]+＝212.1(100％)。
And (3) reacting the azo compound (V) with urea under the catalysis of concentrated sulfuric acid to generate an azobenzimidazolone compound (VI).
21.8g (0.1mol) of azo compound (V) and 13.2g (0.11mol) of urea with the content of 50% are added into a condensation reaction kettle, 80g of water is added, the mixture is heated and kept at 115 ℃ for 2 hours, 3.0g of concentrated sulfuric acid is slowly added in the keeping process, the pH value is controlled at 6.5, the mixture is cooled to room temperature after the reaction is finished, filtered, washed by water and dried at 85 ℃ for 10 hours to obtain 22.1g of azo benzimidazolone compound (VI), the yield is 91.7%, and the purity is 98.7%.
Hydrocracking:
adding 72.3g (0.3mol) of azobenzimidazolone compound (VI), 5g of 5% palladium carbon and 500mL of absolute ethyl alcohol into a 1L stainless steel autoclave with electromagnetic stirring, carrying out hydrogen replacement for 5 times, carrying out hydrogenation (2MPa) at 85 ℃ for 4 hours (sampling and carrying out HPLC tracking till no azobenzimidazolone (VI) peak exists in the system), carrying out hot filtration to recover the catalyst, concentrating the filtrate to recover the absolute ethyl alcohol, carrying out filtration and washing, and drying the filter cake in a vacuum oven to obtain 42.7g of white 5-aminobenzimidazole (TM) solid, wherein mp is 249-252 ℃, the yield is 94.6%, and the purity is 99.0%.
1H-NMR(400MHz,DMSO-d6):
δ10.179(s,1H),10.025(s,1H),6.560(d,1H),6.221(s,1H),6.168(d,1H),4.628(s,2H)；
EI-MS m/z[M]+＝149(100％)。
Example 2
Diazotization of aniline and coupling with o-phenylenediamine
A500 mL beaker was charged with 50mL of water, 37.5mL (0.45mol) of concentrated hydrochloric acid and 14g (0.15mol) of aniline, and 150g of crushed ice was added. Under stirring, 30% sodium nitrite solution 37.0g is dripped into the mixture for 20 minutes at 0-5 ℃, the mixture reacts for 30 minutes at 0-5 ℃, a small amount of sulfamic acid is added until the sodium nitrite is not excessive, and the mixture is filtered to obtain bright yellow clear aniline diazo liquid.
Dissolving 17.3g (0.16mol) of o-phenylenediamine in 500g of hot water, adding acetic acid to adjust the pH value to 5-6, adjusting the temperature to-2-0 ℃, beginning to dropwise add the prepared diazo solution into the o-phenylenediamine solution for unidirectional coupling, keeping the coupling component in slight excess when the coupling is finished, continuing stirring for 30min, raising the temperature to 95 ℃, reacting for 2 hours, filtering, washing with water, and drying to obtain 29.4g of yellow solid (azo compound V), wherein the yield is 91.0% and the purity is 98.5%. EI-MS M/z [ M ]]+＝212.1(100％)。
And (3) reacting the azo compound (V) with urea under the catalysis of concentrated sulfuric acid to generate an azobenzimidazolone compound (VI).
Adding 21.8g (0.12mol) of azo compound (V) and 15.6g (0.13mol) of urea with the content of 50% into a condensation reaction kettle, adding 90g of water, heating to keep the temperature at 115 ℃ for 2 hours, slowly adding 3.5g of concentrated sulfuric acid in the heat preservation process, controlling the pH value to be 6.5, cooling to room temperature after the reaction is finished, filtering, washing with water, and drying at 85 ℃ for 10 hours to obtain 26.9g of azo benzimidazolone compound (VI), wherein the yield is 93.2% and the purity is 99.0%.
Hydrocracking:
60.1g (0.25mol) of azobenzimidazolone compound (VI), 5g of 5% palladium carbon and 500mL of anhydrous methanol are added into a 1L stainless steel autoclave with electromagnetic stirring, hydrogen is replaced for 5 times, hydrogenation (1.5MPa) is carried out at 75 ℃ for 6 hours (sampling is carried out, HPLC tracking is carried out, until no azobenzimidazolone (VI) peak exists in the system), the catalyst is recovered by heat filtration, the filtrate is concentrated and recovered with methanol, the filtrate is filtered and washed with water, and the filter cake is dried in a vacuum oven, so that 35.3g of white 5-aminobenzimidazolone (TM) solid is obtained, wherein mp is 248-251 ℃, the yield is 93.7%, and the purity is 98.9%.
1H-NMR(400MHz,DMSO-d6):
δ10.179(s,1H),10.025(s,1H),6.560(d,1H),6.221(s,1H),6.168(d,1H),4.628(s,2H)；
EI-MS m/z[M]+＝149(100％)。
The foregoing merely represents preferred embodiments of the invention, which are described in some detail and detail, and therefore should not be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, various changes, modifications and substitutions can be made without departing from the spirit of the present invention, and these are all within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (8)
1. A synthetic method for preparing 5-aminobenzimidazole ketone is characterized by comprising the following steps:
(1) diazotization of aniline and coupling with o-phenylenediamine: firstly, carrying out diazotization reaction on aniline to prepare aniline diazonium salt; the aniline diazonium salt is coupled with o-phenylenediamine (I) to generate azo compound (V), and the synthetic route is as follows:
(2) preparation of the azobenzimidazolone compound (VI): the azo compound (V) and urea react under the catalysis of concentrated sulfuric acid to generate an azo benzimidazolone compound (VI), and the synthetic route is as follows:
(3) preparation of 5-aminobenzimidazole ketone (TM): the azo benzimidazolone compound (VI) is subjected to hydrogenation reduction reaction to obtain a target compound 5-amino benzimidazolone (TM), and the synthetic route is as follows:
2. the synthetic method for preparing 5-aminobenzimidazole ketone according to claim 1, wherein the specific process of step (1) is as follows: under the temperature condition of-5 to 5 ℃, adding a certain amount of sodium nitrite into hydrochloric acid solution of aniline, and adding sulfamic acid for reaction to prepare aqueous solution of aniline diazonium salt; and dropwise adding the diazo liquid into an o-phenylenediamine solution at a pH of 5-10 to perform a coupling reaction, wherein the coupling reaction temperature is-6 ℃ to 30 ℃ to obtain the azo compound (V).
3. The synthetic method of claim 2 wherein the coupling reaction temperature is from-4 ℃ to 5 ℃.
4. The synthetic method for preparing 5-aminobenzimidazole ketone according to claim 1 or 2, wherein the molar ratio of aniline to o-phenylenediamine is 1: 0.9 to 1.1.
5. The synthetic method for preparing 5-aminobenzimidazole ketone according to claim 1, wherein the specific process of the step (2) is as follows: mixing an azo compound (V) and urea in a molar ratio of 1: 0.99-1.4, adding a certain amount of water into a condensation reaction kettle, preserving the temperature for 2-3 hours at 90-120 ℃, slowly adding concentrated sulfuric acid in the process of preserving the temperature, controlling the pH value to be 6-7, and drying the obtained material to obtain the azobenzimidazolone compound (VI).
6. The synthetic method for preparing 5-aminobenzimidazole ketone according to claim 1, wherein the specific process of step (3) is as follows: placing azobenzimidazolone compound (VI), a transition metal catalyst and ethanol or methanol in an autoclave, replacing for about 5 times by hydrogen, raising the temperature to the reaction temperature, introducing hydrogen into the autoclave at the pressure of 0.5-3MPa, keeping at 20-100 ℃ for 1-5 hours, filtering out the catalyst from a reaction solution, concentrating the filtrate, carrying out suction filtration, washing with water, and drying the filter cake in vacuum to obtain the 5-aminobenzimidazolone with high purity and yield.
7. The synthetic method of claim 6, wherein the transition metal catalyst is palladium on carbon or Raney nickel catalyst.
8. The synthesis method for preparing 5-aminobenzimidazole ketone according to claim 6, characterized in that the pressure of hydrogen gas introduced into the reaction kettle is 1-3MPa, and the temperature in the reaction kettle is 40-90 ℃.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2933502A (en) * | 1958-02-12 | 1960-04-19 | Du Pont | Benzimidazolone derivatives |
| US4677200A (en) * | 1984-04-05 | 1987-06-30 | Hoechst Aktiengesellschaft | Amino compounds derived from 5-acetoacetylamino-benzimidazolones |
| CN102002002A (en) * | 2010-12-06 | 2011-04-06 | 张家港市蓝迪森新材料科技有限公司 | Preparation method of 5-aminobenzimidazole |
| CN104130194A (en) * | 2014-08-12 | 2014-11-05 | 南通醋酸化工股份有限公司 | Synthesis method of 5-amino benzimidazolone |
-
2021
- 2021-04-30 CN CN202110485209.1A patent/CN113121447B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2933502A (en) * | 1958-02-12 | 1960-04-19 | Du Pont | Benzimidazolone derivatives |
| US4677200A (en) * | 1984-04-05 | 1987-06-30 | Hoechst Aktiengesellschaft | Amino compounds derived from 5-acetoacetylamino-benzimidazolones |
| CN102002002A (en) * | 2010-12-06 | 2011-04-06 | 张家港市蓝迪森新材料科技有限公司 | Preparation method of 5-aminobenzimidazole |
| CN104130194A (en) * | 2014-08-12 | 2014-11-05 | 南通醋酸化工股份有限公司 | Synthesis method of 5-amino benzimidazolone |
Non-Patent Citations (2)
| Title |
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| 王世荣等: "苯并咪唑酮型隐颜料的合成及应用", 《天津大学学报》 * |
| 马洪庆等: "以Ni-B为催化剂合成5-氨基苯并咪唑酮", 《化学工业与工程》 * |
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