Patent US3983170A successfully refreshed from Google Patents.
US3983170A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the purification of malic acid
Assignee: KH Neochem Co Ltd
•
Filing: 1974-12-06
•
Granted: 1976-09-28
•
Expires: 1994-12-06
Abstract
Abstract A process for the purification of D,L-malic acid. An aqueous solution of D,-L-malic acid containing maleic acid and fumaric acid as impurities is treated with a strongly basic anion-exchange resin to remove the maleic acid and fumaric acid to provide substantially pure D,L-malic acid.
Inventors
- 👤 Shozo Sumikawa
- 👤 Rikichi Maida
- 👤 Yuriaki Kageyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 09:18
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/42; C07C51/47
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
40 words
A process for the purification of D,L-malic acid which comprises a step of passing an aqueous malic acid solution containing maleic acid, fumaric acid or a mixture thereof as impurities through a column of a strongly basic anion exchange resin.
Claim 2
Dependent Claim
40 words
A process for the purification of D,L-malic acid which comprises a step of passing an aqueous malic acid solution containing maleic acid, fumaric acid or a mixture thereof as impurities through a column of a strongly basic anion exchange resin.
Claim 3
Dependent Claim
17 words
The process of claim 1, wherein said malic acid solution is further treated with an active carbon.
Claim 4
Dependent Claim
22 words
The process of claim 2, wherein said active carbon is a granular active carbon having a size of 12 to 40 mesh.
Claim 5
Dependent Claim
20 words
The process of claim 1, wherein the malic acid solution is further treated with a strongly acidic cation exchange resin.
Claim 6
Dependent Claim
59 words
A process for purifying D,L-malic acid which comprises passing an aqueous malic acid solution containing maleic acid, fumaric acid or a mixture thereof as impurities through a column of a strongly basic anion exchange resin; and passing the eluate through a column of a granular active carbon and thereafter through a column of a strongly acidic cation exchange resin.
Claim 7
Dependent Claim
59 words
A process for purifying D,L-malic acid which comprises passing an aqueous malic acid solution containing maleic acid, fumaric acid or a mixture thereof as impurities through a column of a strongly basic anion exchange resin; and passing the eluate through a column of a granular active carbon and thereafter through a column of a strongly acidic cation exchange resin.
References Cited (Backward Citations)
US3371112A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-09-28 | 1980-03-29 | 1980-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-09-28 | 1984-03-29 | 1984-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-09-28 | 1988-03-29 | 1988-09-28 | $7700.00 | Window Closed / Lapsed |