Sulphanilic Acid
4-Aminobenzenesulfonic Acid, p-Aminobenzenesulfonic Acid.
- CAS
- 121-57-3
- EC
- 204-482-5
- Sectors
- Textiles, Leather & Paper, Pharma & Healthcare
Sulphanilic Acid (CAS 121-57-3) is an aromatic amine sulfonic acid that carries amino and sulfonic acid functional groups, supplied as a greyish-white crystalline solid in Technical Grade and used as an intermediate for azo dyes, optical brighteners and sulfonamide-based pharmaceuticals and as a diagnostic reagent. It is a critical intermediate in the synthesis of Azo Dyes and various sulfonamide-based pharmaceutical products.
The compound is highly valued for its ability to undergo diazotization, a process essential for creating vibrant dyes and pigments used in the textile and food industries. Its high purity (>99%) ensures consistent quality in the production of optical brighteners and food-safe colorants.
In the medical field, it is used as a diagnostic reagent and as a building block for sulfonamides, a class of synthetic antimicrobial agents. Its stable zwitterionic structure provides high thermal stability, making it a reliable precursor for complex industrial organic chemistry.
Typical Properties
| Molecular formula | C6H7NO3S |
|---|---|
| Molecular weight | 173.19 g/mol |
| Appearance | greyish-white crystals or powder |
| Form | solid |
| Color | White to Off-White |
| Melting point | 288 °C |
| Boiling point | 279 °C |
| Density | 1.485 g/cm³ @ Temp: 25 °C |
| Water solubility | 0.1 g/100 mL (20 °C) |
| pH | 2.5 (10g/l, H2O, 20°C) |
| GHS signal word | Warning · Irritant / harmful |
| HS code | 29214210 |
| Grades available | Technical Grade |
Typical literature values for identification; lot-specific results are stated on the certificate of analysis (COA) and the safety data sheet (SDS) that accompany every delivery.
Sulphanilic Acid
Applications
- Dye Manufacture: Primary intermediate for the production of Acid Orange, Methyl Orange, and various other azo-based textile and food dyes.
- Optical Brighteners: Used in the synthesis of fluorescent whitening agents for the paper and detergent industries to enhance product brightness.
- Pharmaceuticals: Acts as a precursor for sulfa drugs and as a reagent in medical testing for the detection of nitrous acid or bilirubin.
Safety & Risks
Classified as Skin Sensitizer and Eye Irritant. May cause allergic reactions; wear Nitrile Gloves, Lab Coats, and Eye Protection. Handle in a Dust-Controlled Environment.
Packaging
25 kg Woven Bags with PE liners and 500 kg Fiber Drums.