Toluene Sulfonic Acid
AKA “4-Methylbenzenesulfonic acid, P-TOLUENESULFONIC ACID, 104-15-4, 4-Toluenesulfonic acid, p-Toluenesulphonic acid, Tosic acid, Toluene-4-sulfonic acid, p-Tolylsulfonic acid, Tosylic acid, Toluenesulfonic acid
Acid
Ingredient Facts
Toluene sulfonic acid
AKA: 4-Methylbenzenesulfonic acid, P-TOLUENESULFONIC ACID, 104-15-4, 4-Toluenesulfonic acid, P-Toluenesulphonic acid, Tosic acid, Toluene-4-sulfonic acid, P-Tolylsulfonic acid, Tosylic acid, Toluenesulfonic acid
Acid · Cleansing · EWG: 2
Synthetic
Cleanser
Acid
Clean
Toluene-4-sulfonic acid is an arenesulfonic acid that is benzenesulfonic acid in which the hydrogen at position 4 is replaced by a methyl group. It is a member of toluenes and an arenesulfonic acid. It is a conjugate acid of a toluene-4-sulfonate.
Solubility ABOUT 67 G/100 ML WATER; SOL IN ALCOHOL, ETHER
Formula
C7H8O3S
Mol. Weight
172.20
CAS #
104-15-4
Form
Liquid
State
Toluene sulfonic acid, liquid, with more than 5% free sulfuric acid appears as colorless to black solid. Odorless or nearly odorless. (USCG, 1999)
See origin →
Functions
Cleansing
Makes oil and water mix so dirt, makeup, and sunscreen can actually be washed away. The reason your face wash foams.
Hydrotrope
Cleansing Surfactant
Surfactant Hydrotrope
Lifts away dirt and oil
Improves ingredient solubility
Traditional Use
A modern synthetic chemical developed as a catalyst and pH adjuster for cosmetic formulations. Created in the industrial chemistry era for use in complex cosmetic systems.
Skin Types
all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Caution
EWG
2
CIR
Safe as used
Pregnancy
Caution
CIR Safety Findings
Not an Irritant
medical-approval
all-shades-safe
Regulatory Status
USApermitted
EUrestricted
JAPANrestricted
CANADArestricted
Safety assessment of xylene sulfonic acid, toluene sulfonic acid, and alkyl aryl sulfonate hydrotropes as used in cosmetics.
Bergfeld WF, Belsito DV, Klaassen CD, Hill R, Liebler D et al.
International journal of toxicology, 2011
Safety assessment of xylene sulfonic acid, toluene sulfonic acid, and alkyl aryl sulfonate hydrotropes as used in cosmetics.
Bergfeld WF, Belsito DV, Klaassen CD, Hill R, Liebler D et al.
International journal of toxicology, 2011
Safety Assessment of Xylene Sulfonic Acid, Toluene Sulfonic Acid, and Alkyl Aryl Sulfonate Hydrotropes as Used in Cosmetics
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Toluene Sulfonic Acid
European Commission
EU Cosmetic Ingredient Database (CosIng)
Toluene Sulfonic Acid
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR