Ingredient Dictionary

MESITYLENE

1,3,5-trimethylbenzene is a trimethylbenzene carrying methyl substituents at positions 1, 3 and 5.

Definition

1,3,5-trimethylbenzene is a trimethylbenzene carrying methyl substituents at positions 1, 3 and 5.

Source: PubChem

US FDA substance register · UNII 887L18KQ6X · registered name Mesitylene · single chemical substance

Source: US FDA Unique Ingredient Identifier (UNII)

Mesitylene is the organic compound

Cosmetic roles

Base that dissolves other ingredientsSOLVENT

Safety & regulatory references

Not classified under Korea’s toxic-substance GHS list · existing chemical substance

Source: Korea toxic substances GHS register (NIER)

More data — names, identifiers, properties, test records, literature

Names & identifiers

MESITYLENEINCIBenzene, 1,3,5-trimethyl-Synonym

CAS No.chemical registry number: 108-67-8
EC No.EU chemical inventory number: 203-604-4
DTXSIDUS EPA chemical ID: DTXSID6026797
DTXCIDUS EPA compound ID: DTXCID506797

IUPAC: 1,3,5-Trimethylbenzene
Molecular formula: C9H12
Molecular weight: 120.195 g/mol

Measured properties

Appearance: 1,3,5-trimethylbenzene appears as a colorless liquid with a peculiar odor. Insoluble in water and less dense than water. Flash point near 123 °F. May be toxic by ingestion and inhalation. Used to make plastics and dyes. · Liquid
Odour: Peculiar odor · Distinctive, aromatic odor
Boiling point: 329 °F at 760 mmHg (NIOSH, 2024) · 164.7 °C at 760 mm Hg
Melting point: -49 °F (NIOSH, 2024) · -44.8 °C
Solubility: 0.002 % (NIOSH, 2024) · Miscible with alcohol, ether, benzene
Density: 0.86 (NIOSH, 2024) - Less dense than water, will float · 0.8637 at 20 °C/4 °C
Melting/freezing point: -45 ℃
Initial boiling point and range: 165 ℃
Flash point: 50 ℃(c.c.)
Upper/lower flammability or explosive limits: 6.09 / 0.87 % (100℃)
Vapour pressure: 2.48 ㎜Hg(25 ℃)
Water solubility: 48.2 ㎎/ℓ(25℃)
Vapour density: 4.1
Relative density: 0.86
n-Octanol/water partition coefficient (Kow): 3.42
Auto-ignition temperature: 550 ℃
Molecular weight: 120.19

Values measured on the substance itself. The KOSHA data are a reference for writing and reviewing safety data sheets, not a specification for a commercial raw material.

Source: PubChem · KOSHA safety data sheets (Korea)

What products actually use it for

What the 17 products reported to the US EPA with this ingredient use it for. Products outside cosmetics are included, so the top few rows are its main uses.

Solvent6
Degradant/impurity (EPA)3
Intermediate3
Processing aids not otherwise specified2
Diluent1
Fragrance1
Fuel1

Source: US EPA CompTox dashboard

Irritation and sensitisation studies

6 skin studies and 2 eye studies are on record.

Classed as highly irritating2Classed as moderate2

The studies disagree (the most common conclusion covers 50%), so they do not establish that this ingredient is irritating. These tests are on the raw material itself; irritation at the amount in a finished product is a different question.

See all 8 studies

Category 2
Skin Irritation · Screening
Skin corrosion/irritation - Category 2
Skin Irritation · Screening
Severe Irritation
skin irritation: in vivo · Screening · EU Method B.4 (Acute Toxicity: Dermal Irritation / Corrosion) according to
Category 6.3B (Category 3)
Skin Irritation · Read Across
Classification not possible
Skin Sensitization · Screening
Severe Irritation
skin irritation: in vivo · Screening · EU Method B.4 (Acute Toxicity: Dermal Irritation / Corrosion) equivalent or similar to
Category 6.4A (Category 2A)
Eye Irritation · Read Across
Category 2B
Eye Irritation · Screening