US4370487A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for, respectively, the production and purification of dicarboxylic and polycarboxylic acid anhydrides
Assignee: Individual
•
Filing: 1981-04-15
•
Granted: 1983-01-25
•
Expires: 2001-04-15
Abstract
Abstract A method of preparation and/or purification of acid anhydrides is disclosed. Dicarboxylic or polycarboxylic acids contained in the anhydrides to be treated, are dehydrated in an organic solvent in the presence of activated carbon.
Inventors
- 👤 Gerhard Meyer
- 👤 Erich Klimesch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:35
CPC Classifications
C; C07; C07D; C07D493/00; C07D493/02; C07D493/04; C07C; C07C51/00; C07C51/54; C07C51/56; C07C51/573
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
88 words
Process for, respectively, the production and purification of dicarboxylic and polycarboxylic acid anhydrides by dehydration of the respective dicarboxylic or polycarboxylic acids or, in given instances, by dehydration of the respective dicarboxylic or polycarboxylic acids contained in the anhydrides to be purified, characterized by heating at temperatures from 120° to 200° C., the dicarboxylic or polycarboxylic acid, or, respectively, the anhydride to be purified, in an organic solvent in the presence of activated carbon, and by removing the water becoming free thereby in azeotropic solution with the solvent.
Claim 2
Dependent Claim
88 words
Process for, respectively, the production and purification of dicarboxylic and polycarboxylic acid anhydrides by dehydration of the respective dicarboxylic or polycarboxylic acids or, in given instances, by dehydration of the respective dicarboxylic or polycarboxylic acids contained in the anhydrides to be purified, characterized by heating at temperatures from 120° to 200° C., the dicarboxylic or polycarboxylic acid, or, respectively, the anhydride to be purified, in an organic solvent in the presence of activated carbon, and by removing the water becoming free thereby in azeotropic solution with the solvent.
Claim 3
Dependent Claim
33 words
Process as per claim 1, characterized by using a solvent not miscible with water but forming an azeotrope with water, and by azeotropically distilling off, of the separated water together with the solvent.
Claim 4
Dependent Claim
13 words
Process as per claim 1, characterized by using as solvent anisole or phenetole.
Claim 5
Dependent Claim
11 words
Process as per claim 1, characterized by using pulverized activated carbon.
Claim 6
Dependent Claim
25 words
Process as per claim 1, characterized by the quantity of activated carbon amounting to a minimum of 1% by weight relative to the carboxylic acid.
References Cited (Backward Citations)
US1693915A
Cited
US1852782A
Cited
US2518312A
Cited
US2985665A
Cited
US3544602A
Cited
US3948956A
Cited
US3927039A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-01-24 | 1986-07-26 | 1987-01-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-24 | 1990-07-26 | 1991-01-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-24 | 1994-07-26 | 1995-01-25 | $7700.00 | Window Closed / Lapsed |