Common Name(s): Xylene sulfonic acid,acid dimethylbenzenesulfonic acid (xylenesulfonic acid) salt,aromatic sulfonic acid intermediate
CAS Number: 25321-41-9
DESCRIPTION
What It Does: Keeps surfactant-based formulas clear and easy to pour by helping ingredients mix properly.
Why It's Used: Used as a hydrotrope to improve cloud point and reduce viscosity in liquid surfactant systems.
How It Works: Aromatic sulfonate disrupts micellar packing of other surfactants, elevating cloud point and improving clarity.
Typically Found In: Shampoos,liquid cleansers,body washes,surfactant concentrates
TECHNICAL DETAILS
Primary Category: Functional ingredient – surfactant
Secondary Functions: Hydrotrope,viscosity controlling
Application Areas:
Facial Skincare
Body Care
Hair Care
Beard Care
Color Cosmetics (Makeup)
Dietary/Oral Supplements
Typical Concentration Range: 0.5%–5%
SOURCING & ETHICS
Vegan Status: Yes
Halal Status: Yes
Source Notes: Synthetic; petrochemical aromatic sulfonation followed by salt formation.
SKIN COMPATIBILITY
Irritancy Rating: 1/5 – very low
Comedogenicity Rating: 0/5 – non-comedogenic
Sensitivity Concerns: Non-irritating at typical use concentrations.
Safe for Sensitive Skin: Yes
SAFETY & COMPATIBILITY
Safety Profile: Good safety profile. ewg score: 1–2.
Works Well With: Anionic surfactants,amphoteric surfactants,nonionic surfactants
Avoid Combining With: No significant incompatibilities
SCIENTIFIC NOTE
Xylene sulfonic acid (cas 25321-41-9) is the free acid form of xylenesulfonate; typically neutralized to na/k salt for cosmetic hydrotrope use; the acid form used in ph adjustment and manufacturing.
Last Verified: 2026-03-27
Primary Sources: Cosing database,inci dictionary