Process for isolation of dicarboxylic acids and hydroxycarboxylic acids
US5928485A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 4, 1997 |
| Grant date | Jul 27, 1999 |
| Priority date | — |
| Expiry date | Apr 4, 2017 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF26B11/12
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A first process involves the partial electrodialysis of a dialkali metal salt of an aromatic hydroxycarboxylic acid or a dicarboxylic acid to produce the approximate monoalkali metal salt and the alkali metal hydroxide. The monoalkali metal salt is then treated with an acid such as a bisulfate to recover the aromatic hydroxycarboxylic acid or dicarboxylic acid. The resulting inorganic salt such as sodium sulfate may then be electrolyzed to sodium bisulfate and NaOH. A second process involves the electrodialysis at elevated temperatures of a (di)alkali metal salt of p-hydroxybenzoic acid produce free p-hydroxybenzoic acid and the alkali metal hydroxide. These are efficient and economical methods for recovering the acid and alkali metal hydroxide values, as well as the parent organic compound, from these dialkali metal salts.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.