US4260724A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of polymaleic acids from maleic anhydride in the presence of acetic anhydride and of hydrogen peroxide
Assignee: BASF SE
•
Filing: 1979-08-31
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Granted: 1981-04-07
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Expires: 1999-08-31
Abstract
Abstract An improved process for the preparation of polymaleic acids having molecular weights of from 200 to 1,500, by polymerizing maleic anhydride in acetic anhydride in the presence of from 0.2 to 0.5 mole of hydrogen peroxide per mole of maleic anhydride, at from 80° to 140° C., and builders and encrustation inhibitors comprising the polymaleic acids prepared by the said process, for use in detergents.
Inventors
- 👤 Johannes Perner
- 👤 Karl Stork
- 👤 Knut Oppenlaender
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:33
CPC Classifications
C; C11; C11D; C11D3/00; C11D3/16; C11D3/37; C11D3/3746; C11D3/3757; C08; C08F; C08F22/00; C08F22/04; C08F22/06
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
115 words
In a one-step process for the preparation of a polymaleic acid having a molecular weight of from 200 to 1,500, wherein maleic anhydride is polymerized in the presence of hydrogen peroxide and acetic anhydride and the resulting polymaleic anhydride is hydrolyzed, the improvement which comprises: dissolving the maleic anhydride to be polymerized in from 1 to 5 moles of acetic anhydride per mole of maleic anhydride; adding to the maleic anhydride solution from 0.2 to 0.5 mole of hydrogen peroxide per mole of maleic anhydride while at the same time heating the reaction batch to from 80°-140° C., whereupon the polymerization and simultaneous hydrolysis is completed at 100°-140° C., and thereafter isolating the polymaleic acid.
Claim 2
Dependent Claim
115 words
In a one-step process for the preparation of a polymaleic acid having a molecular weight of from 200 to 1,500, wherein maleic anhydride is polymerized in the presence of hydrogen peroxide and acetic anhydride and the resulting polymaleic anhydride is hydrolyzed, the improvement which comprises: dissolving the maleic anhydride to be polymerized in from 1 to 5 moles of acetic anhydride per mole of maleic anhydride; adding to the maleic anhydride solution from 0.2 to 0.5 mole of hydrogen peroxide per mole of maleic anhydride while at the same time heating the reaction batch to from 80°-140° C., whereupon the polymerization and simultaneous hydrolysis is completed at 100°-140° C., and thereafter isolating the polymaleic acid.
Claim 3
Dependent Claim
33 words
The process of claim 1, wherein the reaction is carried out in the presence of from 0.1 to 3%, based on the weight of maleic anhydride, of an inorganic or organic non-oxidizing acid.
Claim 4
Dependent Claim
32 words
The process of claims 1 or 2, wherein the reaction is carried out in the presence of from 0.1 to 3%, based on the weight of maleic anhydride, of a reducing agent.
Claim 5
Dependent Claim
30 words
The process of claim 3, wherein the reaction is carried out in the presence of from 0.1 to 3%, based on the weight of maleic anhydride, of a reducing acid.
Claim 6
Dependent Claim
19 words
A polymaleic acid having a molecular weight of from 200 to 1,500, obtained by the process of claim 1.
Claim 7
Dependent Claim
10 words
A polymaleic acid obtained by the process of claim 2.
Claim 8
Dependent Claim
10 words
A polymaleic acid obtained by the process of claim 3.
Claim 9
Dependent Claim
10 words
A polymaleic acid obtained by the process of claim 4.
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) | 1984-04-06 | 1984-10-06 | 1985-04-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-04-06 | 1988-10-06 | 1989-04-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-04-06 | 1992-10-06 | 1993-04-07 | $7700.00 | Window Closed / Lapsed |