Patent US4550176A successfully refreshed from Google Patents.
US4550176A
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Preparation of imidazole-4,5-dicarboxylic acid
Assignee: BASF SE
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Filing: 1984-01-11
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Granted: 1985-10-29
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Expires: 2004-01-11
Abstract
Abstract Imidazole-4,5-dicarboxylic acid is prepared by a process in which imidazole is reacted with formaldehyde, and the reaction mixture is treated with nitric acid.
Inventors
- 👤 Toni Dockner
- 👤 Uwe Kempe
- 👤 Anton Frank
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:40
CPC Classifications
C; C07; C07D; C07D233/00; C07D233/54; C07D233/66; C07D233/90
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
47 words
A process for the preparation of imidazole-4,5-dicarboxylic acid which comprises: reacting imidazole in a first stage with a 2-fold to 5-fold molar amount of formaldehyde at elevated temperatures, and then treating the reaction mixture in a second stage with nitric acid at from 100° to 140° C.
Claim 2
Dependent Claim
47 words
A process for the preparation of imidazole-4,5-dicarboxylic acid which comprises: reacting imidazole in a first stage with a 2-fold to 5-fold molar amount of formaldehyde at elevated temperatures, and then treating the reaction mixture in a second stage with nitric acid at from 100° to 140° C.
Claim 3
Dependent Claim
24 words
A process as claimed in claim 1, wherein the reaction of imidazole with formaldehyde is carried out in the presence of a strong base.
Claim 4
Dependent Claim
20 words
A process as claimed in claim 1, wherein the reaction of imidazole with formaldehyde is carried out in aqueous solution.
Claim 5
Dependent Claim
23 words
A process as claimed in claim 1, wherein the reaction of imidazole with formaldehyde is carried out at from 80° to 120° C.
Claim 6
Dependent Claim
21 words
A process as claimed in claim 2, wherein the strong base used is an alkali metal or alkaline earth metal hydroxide.
Claim 7
Dependent Claim
21 words
A process as claimed in claim 1, wherein the molar ratio of nitric acid to imidazole is from 15:1 to 20:1.
Claim 8
Dependent Claim
39 words
A process as claimed in claim 1, wherein the first stage reaction of imidazole is carried out in an aqueous solution in the presence of a strong base and at an elevated temperature of from 80° to 120° C.
Claim 9
Dependent Claim
26 words
A process as claimed in claim 7 wherein the strong base is used in an amount of from 30 to 100 mole% based on the imidazole.
Claim 10
Dependent Claim
20 words
A process as claimed in claim 8 wherein the strong base is an alkali metal or alkaline earth metal hydroxide.
Claim 11
Dependent Claim
32 words
A process as claimed in claim 7 wherein the second stage treatment is carried out in aqueous solution with a molar ratio of nitric acid to imidazole of from 15:1 to 20:1.
Claim 12
Dependent Claim
24 words
A process as claimed in claim 10, wherein the second stage treatment is carried out at a temperature of from 130° to 135° C.
Claim 13
Dependent Claim
25 words
A process as claimed in claim 10 wherein the strong base used in the first stage is an alkali metal or alkaline earth metal hydroxide.
Claim 14
Dependent Claim
21 words
A process as claimed in claim 12 wherein the strong base is selected from the group consisting of KOH and NaOH.
Claim 15
Dependent Claim
30 words
A process as claimed in claim 1, wherein the reaction mixture obtained after treatment in said second stage is cooled, and the imidazole-4,5-dicarboxylic acid product is crystallized out and separated.
Claim 16
Dependent Claim
31 words
A process as claimed in claim 14 wherein the first stage reaction time is about 1 to 3 hours, and the second stage reaction time is about 6 to 10 hours.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-10-28 | 1989-04-29 | 1989-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-28 | 1993-04-29 | 1993-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-28 | 1997-04-29 | 1997-10-29 | $7700.00 | Window Closed / Lapsed |