Overview
Benzenesulfonic acid (CAS 98-11-3 ), also known as phenylsulfonic acid, is a strong aromatic sulfonic acid used industrially as a catalyst, pH regulator, and intermediate in the synthesis of dyes, pigments, and surface-active agents.
Its acid strength and water solubility make it a practical processing aid across several chemical manufacturing sectors. In dye and pigment manufacturing, it acts as a sulfonation intermediate and coupling agent.
This chemical directly influences color yield and batch consistency during production. Textile and leather processors use it for pH control during dyeing and tanning operations, where precise acidity affects fiber uptake.
It ensures surface treatment uniformity across various materials. In coatings and resin systems, it functions as an acid catalyst for curing reactions, particularly in baking enamels and crosslinked polymer formulations.
Printing ink formulators incorporate it as a dispersing aid to stabilize pigment suspensions and improve ink flow on press. This versatility makes it a staple in high-performance industrial chemical applications.
Benzenesulfonic acid is supplied as an aqueous solution, most commonly at concentrations around 65–70%, and as a dry crystalline solid. Technical grade is the standard commercial form for industrial synthesis.
Higher-purity grades are available for catalyst and specialty chemical applications where consistent acid content and low impurity profiles are required. These standards ensure reliability in sensitive manufacturing environments.
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Physical Properties
| Melting Point | 65 °C |
| Boiling Point | 137°C |
| Density | 1.32 |
| Flash Point | >230 °F |
| Appearance | green solid |
| Color | Yellow to light brown |
| Form | Damp Crystalline Solid or Fused Mass |
| Water Solubility | soluble |
| Vapor Pressure | 69.8Pa at 20℃ |
| Refractive Index | 1.5151 (estimate) |
| pH | 2 (H2O, 20℃)(saturated solution) |
| Log P | 0.41 at 25℃ |
Safety & Handling
Danger GHS05 GHS07 Hazard Statements H290 May be corrosive to metals H302 Harmful if swallowed H314 Causes severe skin burns and eye damage H318 Causes serious eye damage Precautionary Statements P234 Keep only in original packaging. P260 Do not breathe dust/fume/gas/mist/vapours/spray. P264 Wash … thoroughly after handling. P270 Do not eat, drink or smoke when using this product. P280 Wear protective gloves/protective clothing/eye protection/face protection. P316 Get emergency medical help immediately. P317 Get emergency medical help. P321 Specific treatment (see … on this label). P330 Rinse mouth. P363 Wash contaminated clothing before reuse. P390 Absorb spillage to prevent material damage. P405 Store locked up. P406 Store in a corrosion-resistant/… container with a resistant inner liner. P501 Dispose of contents/container in accordance with local regulations. P264+P265 Wash … thoroughly after handling. P301+P317 Get emergency medical help. P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing. P301+P330+P331 Rinse mouth. Do NOT induce vomiting. P302+P361+P354 IF ON SKIN: Take off immediately all contaminated clothing. Rinse skin with water/shower. P305+P354+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 | 29041000 |
| UN Number | 2583 |
| ADR Class | 8 |
| Packing Group | II |
| Storage Class | 8A - Combustible corrosive hazardous materials |
| WGK (Germany) | 1 |
Other Names
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Chemical Properties
- CAS Number
- 98-11-3
- EC Number
- 202-638-7
- Mol. Weight
- 158.18
- HS Code
- 29041000
- Category
- UV Absorbers & Stabilizers