Use of 4,4'-dinitrostilbene-2,2'-disulfonic acid wastewater as a raw material for paramycin production

This study uses 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNS) wastewater to produce paramycin (4-amino-2-hydroxybenzoic acid), an antitubercular agent and important pharmaceutical intermediate. The high concentrations of aromatic sulfonic acids contained in the wastewater, derived from a DNS production facility, have been transformed to paramycin in yields of more than 85%. This waste-disposal strategy, which combines oxidation using NaClO, reduction using iron powder, and subsequent alkaline fusion with NaOH, has been proven to be successful in dealing with ton-scale DNS wastewater. Compared with common treatment methods, which usually involve degrading the compounds, this new method recycles most of the aromatic sulfonic acids in the wastewater to produce paramycin. This effectively solves the associated environment problems associated with DNS wastewater and is also potentially profitable. The present approach could also lead to alternative solutions for dealing with other industrial wastewaters generated from oxidative coupling reactions of nitro-substituted toluenes to the corresponding substituted stilbenes.