3-Nitrobenzenesulfonic acid

3-Nitrobenzenesulfonic acid (CAS 98-47-5) is an aromatic sulfonic acid carrying a nitro substituent at the meta position. It is also referenced under the names m-Nitrobenzenesulfonic acid, 3-Nitrophenylsulfonic acid, and NSC 166284. No assigned E-code applies to this substance.

In pharmaceutical synthesis, it serves as an acid catalyst and intermediate in sulfonation reactions, facilitating the formation of dye precursors and active pharmaceutical ingredients. In textile and leather processing, it functions as a coupling component and pH-regulating agent during dyeing operations, where its dual functional groups enable controlled reactivity with fiber substrates.

This compound is supplied for industrial and research applications and falls under REACH registration requirements for quantities above one tonne per year within the EU. Procurement teams should confirm supplier documentation including Safety Data Sheets and certificates of analysis. Packaging formats and available grades vary by supplier and should be confirmed at the point of enquiry.