US4269989A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the preparation of benzimidazolone-(2)
Assignee: Hoechst AG
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Filing: 1979-12-19
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Granted: 1981-05-26
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Expires: 1999-12-19
Abstract
Abstract Benzimidazolone-(2) is obtained in good yield and high purity when o-phenylene diamine is condensed with urea in water at a pH of 4 to 9 and a temperature above 90° C.
Inventors
- 👤 Hartmut Heise
- 👤 Ernst Hille
- 👤 Reinhard Wagner
- 👤 Kurt Kummerle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 23:02
CPC Classifications
C; C07; C07D; C07D235/00; C07D235/02; C07D235/04; C07D235/24; C07D235/26
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
63 words
In a process for the preparation of benzimidazolone-(2) by heating o-phenylenediamine and an excess of urea in water to a temperature of at least 90° C., the improvement comprising heating o-phenylenediamine and an excess amount of urea, the molar ratio of urea to o-phenylenediamine being up to 1.5:1, and maintaining the pH in a range of from 4 to 9 throughout the reaction.
Claim 2
Dependent Claim
63 words
In a process for the preparation of benzimidazolone-(2) by heating o-phenylenediamine and an excess of urea in water to a temperature of at least 90° C., the improvement comprising heating o-phenylenediamine and an excess amount of urea, the molar ratio of urea to o-phenylenediamine being up to 1.5:1, and maintaining the pH in a range of from 4 to 9 throughout the reaction.
Claim 3
Dependent Claim
16 words
A process as claimed in claim 1, wherein the pH is of from 4 to 8.
Claim 4
Dependent Claim
16 words
A process as claimed in claim 1, wherein the pH is of from 4.5 to 7.
Claim 5
Dependent Claim
16 words
A process as claimed in claim 1, wherein the reaction temperature is at least 100° C.
Claim 6
Dependent Claim
15 words
A process as claimed in claim 1, wherein the reaction is performed without applying pressure.
Claim 7
Dependent Claim
39 words
A process as claimed in claim 1, wherein o-phenylene diamine and part of the urea are introduced into a reaction vessel and further amounts of urea and the acid for maintaining said pH range are added during the reaction.
Claim 8
Dependent Claim
23 words
A process as claimed in claim 1, wherein at the beginning of the reaction less than the stoichiometric amount of urea is present.
Claim 9
Dependent Claim
36 words
A process as claimed in claim 1, wherein o-phenylene diamine and water are introduced into a reaction vessel and urea and the acid for maintaining said pH range are added in the course of the reaction.
Claim 10
Dependent Claim
21 words
A process as claimed in claim 1, wherein at the end of the reaction the pH is adjusted to above 5.
Claim 11
Dependent Claim
21 words
A process as claimed in claim 1, wherein at the end of the reaction the pH is adjusted to above 6.
Claim 12
Dependent Claim
16 words
A process as claimed in claim 1, wherein the reaction is performed under exclusion of oxygen.
Claim 13
Dependent Claim
17 words
A process as claimed in claim 1, wherein a reducing agent is added to the reaction mixture.
Claim 14
Dependent Claim
20 words
A process as claimed in claim 12, wherein the reducing agent is an alkali metal dithionite, sulfite or hydrogen sulfite.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-05-25 | 1984-11-24 | 1985-05-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-05-25 | 1988-11-24 | 1989-05-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-05-25 | 1992-11-24 | 1993-05-26 | $7700.00 | Window Closed / Lapsed |