CA1132582A - Process for the preparation of 5-nitrobenzimidazolone-(2) - Google Patents
Process for the preparation of 5-nitrobenzimidazolone-(2)Info
- Publication number
- CA1132582A CA1132582A CA345,289A CA345289A CA1132582A CA 1132582 A CA1132582 A CA 1132582A CA 345289 A CA345289 A CA 345289A CA 1132582 A CA1132582 A CA 1132582A
- Authority
- CA
- Canada
- Prior art keywords
- nitric acid
- benzimidazolone
- weight
- concentration
- nitrobenzimidazolone
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
PROCESS FOR THE PREPARATION OF 5-NITROBENZIMIDAZOLONE-(2) Abstract of the disclosure:
Nitration of benzimidazolone-(2) with nitric acid in water at 20 to 100°C yields 5-nitrobenzimidazolone-(2) in high yield and purity. Since no side reactions occur the mother liquor can be recycled, thus avoiding waste water problems. The product can be reduced to 5-aminobenzimida-zolone-(2) which is a diazo component for azo dyes which, in turn, can be reacted with diketene to yield 5-acetoace-tylamino-benzimidazolone which is a coupling component for azo dyes, especially pigments.
Nitration of benzimidazolone-(2) with nitric acid in water at 20 to 100°C yields 5-nitrobenzimidazolone-(2) in high yield and purity. Since no side reactions occur the mother liquor can be recycled, thus avoiding waste water problems. The product can be reduced to 5-aminobenzimida-zolone-(2) which is a diazo component for azo dyes which, in turn, can be reacted with diketene to yield 5-acetoace-tylamino-benzimidazolone which is a coupling component for azo dyes, especially pigments.
Description
113~58Z
5-Nitrobenzimidazolone-(2) serves as starting material for the prep-aration of the corresponding amino compound which is used as diazo component or in the form of the corresponding N-acetoacetyl compound as coupling compon-ent for azo dyes, especially pigments.
Nitration of benzimidazolone-(2) is state of the art. For example, in Zhur.Obshchei Khim. 27 (1957) 127-135 is described that benzimidazolone is dissolved in concentrated sulfuric acid, a mixture of concentrated sulfuric acid and the about equimolar amount of fuming nitric acid is added at 0C with vigorous agitation, and 5-nitrobenzimidazolone-~2) is isolated with a yield of 68.5% after a complicated work-up. However, under the same reaction conditions crude 5,6-dinitrobenzimidazolone-(2) is obtained with a yield of 94% by using the about 3-fold molar amount of fuming nitric acid. Apart from the complic-ated and expensive work-up, a further disadvantage of this process therefore resides in the fact that higher nitro compounds are obtained even at low tem-peratures in addition to the intended mononitro compound.
In Monatshefte fùr Chemie 107 (1976) 1307-1310 is described that ben-zimidazolone is reacted at a temperature of up to 30C in a mixture of acetic anhydride and glacial acetic acid with a nitrating suspension of the about 4,5-fold molar amount of concentrated nitric acid, glacial acetic acid and urea. Although in this process 5-nitrobenzimidazolone-(2) is obtained with a yield of 90.5%, the use of an organic solvent mixture, the high excess of con-centrated nitric acid and the thus required expensive work-up of the dilute acids formed are disadvantageous. When the nitration is carried out at 40 C
with concentrated nitric acid alone, the 5-nitro compound and the 5,6-dinitro compound are obtained in a ratio of about 1:5, and at 70C the dinitro com-pound alone is isolated.
According to these known processes, a water-binding reaction medium was used for the nitration of benzimidazolone-(2), that is, either concentrat-.~ ~
`` 1~3;~58;~
ed sulfuric acid or acetic anhydride. Surprisingly, there has now been foundthat the nitration reaction proceeds very smoothly in water as reaction medi-um.
Subject of the invention is therefore a process for the preparation of 5-nitrobenzimidazolone-(2) by reaction of benzimidazolone-(2) with nitric acid in a liquid medium, wherein the liquid medium is water and nitration iS
carried out at a temperature of from 20 to 100C.
Preferred embodiments of the invention are described as follows;
percentages being by weight:
The concentration of aqueous nitric acid should preferably not be below 10%, because otherwise the reaction would proceed too slowly even at temperatures near 100C. On the other hand, when working at a temperature of about 80 - 85C, a concentration of 10 - 12% is sufficient to obtain a reason-able time/conversion ratio. Operations at the lower limit of the temperature range as claimed require a nitric acid concentration of at least 45%. A high-er nitric acid concentration, however, is disadvantageous because formation of higher nitrated products may occur in this case. Moreover, the solubility of the nitrobenzimidazolone in the reaction medium is increased, so that after completed reaction a relatively large amount of water must be added for com-plete precipitation of the nitro compound.
For all these reasons, a concentration range of from about 10 to 45%
is preferred; the reaction temperature being from 30 to 80C.
The molar ratio of nitric acid to benzimidazolone may vary within relatively wide limits. Since the nitric acid concentration should not be be-low 10% towards the end of the reaction in order to ensure a complete nitra-tion, the mclar ratio is advantageously in a range of from 2 to 4 mols of nit-ric acid per mol of benzimidazolone.
According to an advantageous embodiment of the process of the inven-~13'~582 tion, the benzimidazoIone is introduced with agitation into an about 26% nit-ric acid. Nitration starts at about 30C and is terminated at about 35 C.
A special advantage of the process of the invention resides in the fact that due to the uniformly proceeding nitration the mother liquor can be freshened up to attain the starting concentration, and reused. This recovery of nitric acid merely needs to compensate the minimal losses which occur due to small mother liquor amounts adhering to the final product on isolation.
As a result, practically one mol of nitric acid is required only per mol of benzimidazolone. Thus, no problems of working up the aqueous nitric acid arise, especially with respect to pollution.
The following examples illustrate the invention. Parts by volume and by weight are in a ratio as that of kilogram to liter; percentages being by weight also in these cases.
EXAMPLE 1:
600 Parts by volume of water are introduced into a vessel provided with agitator and 150 parts by volume of industrial grade nitric acid (99%
strength, d = 1.51) are added at room temperature with agitation and cooling, so that 750 parts by volume of a 26% nitric acid are then present (d = 1.157).
At 25 C, 180 parts by weight of benzimidazolone are added in the form of an about 75% aqueous press cake (corresponding to 134 p.b.w. = 1 mol). The tem-perature should not rise above 35C. The solution being transparent at the start becomes turbid soon, and the 5-nitrobenzimidazolone begins to precipit-ate. After the addition is complete, agitation is continued for 1 hour at 35C. Subsequently, the batch is diluted with 1000 parts by volume of water, and agitation is continued for 1/2 hour. Subsequently, the product is suc tion-filtered via an acid-proof suction filter, washed to nearly neutral with water, and the nitro compound is dried at 105C.
173 Parts by weight of 5-nitrobenzimidazolone-~2) are obtained, , ~
~1325~32 corresponding to a yield of 97%, relative to benzimidazolone used. The prod-uct proves to be uniform in thin-layer chromatography and has a melting point of 308C.
EX~PLE 2:
.
840 Parts by weight of water are introduced into a vessel provided with agitator, and 161 parts by weight of a 99% industrial grade nitric acid (d = 1.51) are added at room temperature with agitation and cooling. lO01 parts by weight of a 16% nitric acid are thus obtained. The mixture is heat-ed to 50C, and 180 parts by weight of benzimidazolone in the form of an about 75% aqueous press cake (1 mol) are added with agitation. The reaction is controlled in such a manner that the nitration proceeds within 2 hours at 50 - 75 C. The batch is heated to 90C for 1/2 hour in order to improve the filterability of the 5-nitrobenzimidazolone-(2), then cooled to room temper-ature and suction-filtered via an acid-proof suction filter. The further work-up is as described in Example 1. The yield of nitro compound is 96%, relative to benzimidazolone used.
EXAMPLE 3:
The mother liquor of Example 2 (about 800 parts by weight of about 10% aqueous nitric acid) is freshened up with 65 parts by weight of a 99%
nitric acid, and a nitration i5 carried out as in Example 2.
The 5-nitrobenzimidazolone-(2) is obtained with a yield of 98%, relative to benzimidazolone used, and uniform quality according to thin-layer chromatography.
5-Nitrobenzimidazolone-(2) serves as starting material for the prep-aration of the corresponding amino compound which is used as diazo component or in the form of the corresponding N-acetoacetyl compound as coupling compon-ent for azo dyes, especially pigments.
Nitration of benzimidazolone-(2) is state of the art. For example, in Zhur.Obshchei Khim. 27 (1957) 127-135 is described that benzimidazolone is dissolved in concentrated sulfuric acid, a mixture of concentrated sulfuric acid and the about equimolar amount of fuming nitric acid is added at 0C with vigorous agitation, and 5-nitrobenzimidazolone-~2) is isolated with a yield of 68.5% after a complicated work-up. However, under the same reaction conditions crude 5,6-dinitrobenzimidazolone-(2) is obtained with a yield of 94% by using the about 3-fold molar amount of fuming nitric acid. Apart from the complic-ated and expensive work-up, a further disadvantage of this process therefore resides in the fact that higher nitro compounds are obtained even at low tem-peratures in addition to the intended mononitro compound.
In Monatshefte fùr Chemie 107 (1976) 1307-1310 is described that ben-zimidazolone is reacted at a temperature of up to 30C in a mixture of acetic anhydride and glacial acetic acid with a nitrating suspension of the about 4,5-fold molar amount of concentrated nitric acid, glacial acetic acid and urea. Although in this process 5-nitrobenzimidazolone-(2) is obtained with a yield of 90.5%, the use of an organic solvent mixture, the high excess of con-centrated nitric acid and the thus required expensive work-up of the dilute acids formed are disadvantageous. When the nitration is carried out at 40 C
with concentrated nitric acid alone, the 5-nitro compound and the 5,6-dinitro compound are obtained in a ratio of about 1:5, and at 70C the dinitro com-pound alone is isolated.
According to these known processes, a water-binding reaction medium was used for the nitration of benzimidazolone-(2), that is, either concentrat-.~ ~
`` 1~3;~58;~
ed sulfuric acid or acetic anhydride. Surprisingly, there has now been foundthat the nitration reaction proceeds very smoothly in water as reaction medi-um.
Subject of the invention is therefore a process for the preparation of 5-nitrobenzimidazolone-(2) by reaction of benzimidazolone-(2) with nitric acid in a liquid medium, wherein the liquid medium is water and nitration iS
carried out at a temperature of from 20 to 100C.
Preferred embodiments of the invention are described as follows;
percentages being by weight:
The concentration of aqueous nitric acid should preferably not be below 10%, because otherwise the reaction would proceed too slowly even at temperatures near 100C. On the other hand, when working at a temperature of about 80 - 85C, a concentration of 10 - 12% is sufficient to obtain a reason-able time/conversion ratio. Operations at the lower limit of the temperature range as claimed require a nitric acid concentration of at least 45%. A high-er nitric acid concentration, however, is disadvantageous because formation of higher nitrated products may occur in this case. Moreover, the solubility of the nitrobenzimidazolone in the reaction medium is increased, so that after completed reaction a relatively large amount of water must be added for com-plete precipitation of the nitro compound.
For all these reasons, a concentration range of from about 10 to 45%
is preferred; the reaction temperature being from 30 to 80C.
The molar ratio of nitric acid to benzimidazolone may vary within relatively wide limits. Since the nitric acid concentration should not be be-low 10% towards the end of the reaction in order to ensure a complete nitra-tion, the mclar ratio is advantageously in a range of from 2 to 4 mols of nit-ric acid per mol of benzimidazolone.
According to an advantageous embodiment of the process of the inven-~13'~582 tion, the benzimidazoIone is introduced with agitation into an about 26% nit-ric acid. Nitration starts at about 30C and is terminated at about 35 C.
A special advantage of the process of the invention resides in the fact that due to the uniformly proceeding nitration the mother liquor can be freshened up to attain the starting concentration, and reused. This recovery of nitric acid merely needs to compensate the minimal losses which occur due to small mother liquor amounts adhering to the final product on isolation.
As a result, practically one mol of nitric acid is required only per mol of benzimidazolone. Thus, no problems of working up the aqueous nitric acid arise, especially with respect to pollution.
The following examples illustrate the invention. Parts by volume and by weight are in a ratio as that of kilogram to liter; percentages being by weight also in these cases.
EXAMPLE 1:
600 Parts by volume of water are introduced into a vessel provided with agitator and 150 parts by volume of industrial grade nitric acid (99%
strength, d = 1.51) are added at room temperature with agitation and cooling, so that 750 parts by volume of a 26% nitric acid are then present (d = 1.157).
At 25 C, 180 parts by weight of benzimidazolone are added in the form of an about 75% aqueous press cake (corresponding to 134 p.b.w. = 1 mol). The tem-perature should not rise above 35C. The solution being transparent at the start becomes turbid soon, and the 5-nitrobenzimidazolone begins to precipit-ate. After the addition is complete, agitation is continued for 1 hour at 35C. Subsequently, the batch is diluted with 1000 parts by volume of water, and agitation is continued for 1/2 hour. Subsequently, the product is suc tion-filtered via an acid-proof suction filter, washed to nearly neutral with water, and the nitro compound is dried at 105C.
173 Parts by weight of 5-nitrobenzimidazolone-~2) are obtained, , ~
~1325~32 corresponding to a yield of 97%, relative to benzimidazolone used. The prod-uct proves to be uniform in thin-layer chromatography and has a melting point of 308C.
EX~PLE 2:
.
840 Parts by weight of water are introduced into a vessel provided with agitator, and 161 parts by weight of a 99% industrial grade nitric acid (d = 1.51) are added at room temperature with agitation and cooling. lO01 parts by weight of a 16% nitric acid are thus obtained. The mixture is heat-ed to 50C, and 180 parts by weight of benzimidazolone in the form of an about 75% aqueous press cake (1 mol) are added with agitation. The reaction is controlled in such a manner that the nitration proceeds within 2 hours at 50 - 75 C. The batch is heated to 90C for 1/2 hour in order to improve the filterability of the 5-nitrobenzimidazolone-(2), then cooled to room temper-ature and suction-filtered via an acid-proof suction filter. The further work-up is as described in Example 1. The yield of nitro compound is 96%, relative to benzimidazolone used.
EXAMPLE 3:
The mother liquor of Example 2 (about 800 parts by weight of about 10% aqueous nitric acid) is freshened up with 65 parts by weight of a 99%
nitric acid, and a nitration i5 carried out as in Example 2.
The 5-nitrobenzimidazolone-(2) is obtained with a yield of 98%, relative to benzimidazolone used, and uniform quality according to thin-layer chromatography.
Claims (10)
- THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
l. In a process for the preparation of 5-nitrobenzimidazolone-(2) by reacting benzimidazolone-(2) with nitric acid in a liquid medium the im-provement comprising performing the nitration in water at a temperature of 20 to 100°C. - 2. A process as claimed in claim 1, wherein the reaction temper-ature is 30 to 80°C.
- 3. A process as claimed in claim 1, wherein the concentration of the nitric acid is 10 to 45% by weight.
- 4. A process as claimed in claim 1, wherein 2 to 4 mols of nitric acid are added per mol of benzimidazolone-(2) to the reaction mixture.
- 5. A process as claimed in claim 1, wherein the mother liquor of a previous reaction is used as the reaction medium.
- 6. A process as claimed in claim 1, wherein the temperature is 80 to 85°C and the concentration of the nitric acid is 10 to 12% by weight.
- 7. A process as claimed in claim l, wherein the temperature is about 20°C and the concentration of the nitric acid is about 45% by weight.
- 8. A process as claimed in claim l, wherein benzimidazolone-(2) is added to nitric acid of a concentration of 26% by weight at a temperature of about 30°C and is reacted further at about 35°C.
- 9. A process as claimed in claim 1, wherein benzimidazolone-(2) is added to nitric acid of a concentration of 16 % by weight at a temperature of about 50°C and is reacted further at 50 to 75°C.
- 10. A process as claimed in claim 1, wherein the mother liquor of a previous nitration is adjusted with concen-trated nitric acid to the desired concentration and reacted with benzimidazolone-(2).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19792905126 DE2905126A1 (en) | 1979-02-10 | 1979-02-10 | METHOD FOR PRODUCING 5-NITROBENZIMIDAZOLONE- (2) |
| DEP2905126.1 | 1979-02-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1132582A true CA1132582A (en) | 1982-09-28 |
Family
ID=6062649
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA345,289A Expired CA1132582A (en) | 1979-02-10 | 1980-02-08 | Process for the preparation of 5-nitrobenzimidazolone-(2) |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0014449B1 (en) |
| JP (1) | JPS55111471A (en) |
| AU (1) | AU530061B2 (en) |
| BR (1) | BR8000800A (en) |
| CA (1) | CA1132582A (en) |
| DE (2) | DE2905126A1 (en) |
| IN (1) | IN150238B (en) |
| MX (1) | MX152429A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108329273A (en) * | 2017-12-21 | 2018-07-27 | 山东汇海医药化工有限公司 | A kind of method of second nitrification synthesis 5-Nitro-2-benzimidazolinone |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4334269B2 (en) * | 2002-04-18 | 2009-09-30 | 株式会社ワイケイワイ | Golf club display support device |
-
1979
- 1979-02-10 DE DE19792905126 patent/DE2905126A1/en not_active Withdrawn
-
1980
- 1980-02-04 DE DE8080100536T patent/DE3062853D1/en not_active Expired
- 1980-02-04 IN IN130/CAL/82A patent/IN150238B/en unknown
- 1980-02-04 EP EP80100536A patent/EP0014449B1/en not_active Expired
- 1980-02-08 AU AU55346/80A patent/AU530061B2/en not_active Expired
- 1980-02-08 CA CA345,289A patent/CA1132582A/en not_active Expired
- 1980-02-08 JP JP1379280A patent/JPS55111471A/en active Granted
- 1980-02-08 MX MX181118A patent/MX152429A/en unknown
- 1980-02-08 BR BR8000800A patent/BR8000800A/en not_active IP Right Cessation
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108329273A (en) * | 2017-12-21 | 2018-07-27 | 山东汇海医药化工有限公司 | A kind of method of second nitrification synthesis 5-Nitro-2-benzimidazolinone |
| 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 |
Also Published As
| Publication number | Publication date |
|---|---|
| AU5534680A (en) | 1980-08-14 |
| EP0014449B1 (en) | 1983-04-27 |
| JPS6326752B2 (en) | 1988-05-31 |
| EP0014449A2 (en) | 1980-08-20 |
| AU530061B2 (en) | 1983-06-30 |
| IN150238B (en) | 1982-08-21 |
| JPS55111471A (en) | 1980-08-28 |
| DE3062853D1 (en) | 1983-06-01 |
| MX152429A (en) | 1985-07-15 |
| BR8000800A (en) | 1980-10-29 |
| DE2905126A1 (en) | 1980-08-21 |
| EP0014449A3 (en) | 1980-09-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |