Process for the preparation of crystalline, salt-free, chlorine-substituted 3-nitrobenzenesulfonic acid hydrates
US5451699A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 6, 1994 |
| Grant date | Sep 19, 1995 |
| Priority date | — |
| Expiry date | Apr 6, 2014 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C303/44
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
The present invention relates to a process for the preparation of crystalline, salt-free, chlorine-substituted 3-nitrobenzenesulfonic acid hydrates from sulfonation mixtures containing chlorine-substituted 3-nitrobenzenesulfonic acid, in which the sulfonation mixture is mixed with from 8 to 25% strength by weight aqueous sulfuric acid at from 40.degree. C. to 100.degree. C., the resulting suspension is cooled to from 5.degree. C. to 20.degree. C., the precipitate is filtered off and dissolved with water at from 30.degree. C. to 100.degree. C., filtration is carried out if desired, the solution is cooled to from 5.degree. to 40.degree. C. and filtered, and the sulfuric acid-containing filtrate is recycled if desired.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.