Overview
Sulfanilic acid (CAS 121-57-3 ), also known as sulphanilic acid, is an aminosulfonic acid used as a key intermediate in the synthesis of azo dyes, optical brighteners, and specialty chemicals.
Its bifunctional structure, carrying both amine and sulfonic acid groups, makes it a productive building block for coupling reactions in dye manufacturing and industrial chemical synthesis.
In textile dyeing, this compound is diazotized and coupled with naphthol or other aromatic compounds to produce direct and reactive azo dyes used on cotton and wool fibers.
The paper and packaging industries rely on it to manufacture fluorescent whitening agents that improve brightness in various coated and uncoated paper grades across the global market.
Leather processing operations use derivatives of this acid to achieve consistent, penetrating coloration on finished hides. It also functions as a cross-linking component in polymeric colorants.
Furthermore, it is utilized in the production of pigment dispersants for printing inks. The material is supplied as a white to off-white crystalline powder for industrial handling.
Technical grade is the standard commercial form, with purity typically specified at 99% minimum for dye intermediate applications. Reagent-grade material is available for laboratory use.
Analytical applications often require tighter specifications for consistency. Our product meets rigorous industrial benchmarks to ensure performance in complex chemical synthesis and manufacturing.
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Physical Properties
| Melting Point | 288 °C |
| Boiling Point | 279 °C |
| Density | 1.485 g/cm³ @ Temp: 25 °C |
| Appearance | greyish-white crystals or powder |
| Color | White to Off-White |
| Form | solid |
| Water Solubility | 0.1 g/100 mL (20 ºC) |
| Vapor Pressure | 0Pa at 25℃ |
| Refractive Index | 1.5500 (estimate) |
| pH | 2.5 (10g/l, H2O, 20℃) |
| Log P | -2.3 at 25℃ |
Safety & Handling
Warning GHS07 Hazard Statements H315 Causes skin irritation H317 May cause an allergic skin reaction H319 Causes serious eye irritation Precautionary Statements P261 Avoid breathing dust/fume/gas/mist/vapours/spray. P264 Wash … thoroughly after handling. P272 Contaminated work clothing should not be allowed out of the workplace. P280 Wear protective gloves/protective clothing/eye protection/face protection. P321 Specific treatment (see … on this label). P501 Dispose of contents/container in accordance with local regulations. P264+P265 Wash … thoroughly after handling. P302+P352 IF ON SKIN: Wash with plenty of water. P332+P317 Get emergency medical help. P333+P317 Get emergency medical help. P337+P317 If eye irritation persists: Get medical advice/attention. Get emergency medical help. P362+P364 Take off contaminated clothing and wash it before reuse. P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
Trade & Regulatory
| HS Code | 29214210 |
| UN Number | 2790 |
| ADR Class | 8 |
| Packing Group | III |
| WGK (Germany) | 1 |
Other Names
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Chemical Properties
- CAS Number
- 121-57-3
- EC Number
- 204-482-5
- Mol. Weight
- 173.19
- HS Code
- 29214210
- Category
- Monomers & Building Blocks