What is Sulfanilic Acid?
Sulfanilic Acid (CAS 121-57-3) is an important organic compound widely used in the dye, pigment, pharmaceutical, and chemical industries. With the molecular formula C6H7NO3S and a molecular weight of 173.19 g/mol, it contains both an amine (-NH2) and a sulfonic acid (-SO3H) functional group attached to a benzene ring. This dual functionality makes it highly valuable as a chemical intermediate.
The compound typically appears as a white to light beige crystalline powder, soluble in water and slightly soluble in alcohol. Due to its ability to form diazonium salts, sulfanilic acid plays a crucial role in the synthesis of azo dyes and related derivatives.
Key Properties of Sulfanilic Acid (121-57-3)
CAS Number: 121-57-3
Chemical Formula: C6H7NO3S
Appearance: White to off-white crystalline powder
Solubility: Soluble in water, slightly soluble in ethanol
Stability: Stable under normal storage conditions
Reactivity: Readily forms diazonium salts, suitable for azo dye manufacturing
Applications of Sulfanilic Acid
1. Dyes and Pigments
Sulfanilic acid is a key intermediate in the production of azo dyes such as Methyl Orange, Acid Orange, and Direct Dyes. It provides strong, stable colors that are widely used in textiles, paper, and leather processing.
2. Optical Brightening Agents
It is also used in the manufacture of optical brighteners that enhance the whiteness and brightness of fabrics and paper products.
3. Pharmaceutical Industry
Sulfanilic acid is an important precursor for sulfa drugs and other pharmaceutical intermediates. Its ability to interact with other organic compounds makes it useful in active pharmaceutical ingredient (API) production.
4. Analytical Chemistry
In laboratories, sulfanilic acid is widely applied for the quantitative determination of nitrate and nitrite ions in environmental testing, food safety analysis, and water quality monitoring.
5. Other Uses
Electroplating chemicals
Specialty resins and polymers
Restricted applications in food colorants (regulated by region)
Safety and Handling
Hazards: May cause irritation to eyes, skin, and respiratory tract.
Protective Measures: Use personal protective equipment (gloves, goggles, protective clothing).
Storage Conditions: Store in a cool, dry, and well-ventilated area, away from oxidizing agents.
Regulatory Compliance: Ensure handling and transport follow local and international chemical safety standards.
Global Market and Suppliers
The global demand for Sulfanilic Acid 121-57-3 continues to grow, especially in Asia-Pacific regions where textile and dye industries are expanding. China and India are among the leading manufacturers, supplying to Europe, North America, and the Middle East.
B2B buyers in the dye, pharmaceutical, and specialty chemical sectors often look for:
High-purity sulfanilic acid
Reliable supply chain partners
Competitive pricing for bulk orders
Compliance with international standards (ISO, REACH, etc.)
Why Choose a Trusted Supplier?
Selecting a reliable sulfanilic acid manufacturer is essential for consistent quality and timely delivery. Leading suppliers provide:
Verified COA (Certificate of Analysis)
Batch-to-batch consistency
Fast global shipping
Technical support for industrial applications
Conclusion
Sulfanilic Acid (CAS 121-57-3) is a versatile and indispensable chemical raw material for azo dyes, optical brighteners, pharmaceuticals, and analytical reagents. With stable demand across multiple industries, sourcing from a reputable global supplier ensures high quality, safety, and compliance.