Substance profile
Mesitylene
Mesitylene is a clear, colorless liquid with a peculiar odor.
01 · Identification
What Mesitylene is
Mesitylene is a clear, colorless liquid with a peculiar odor. Its molecular formula is C9H12 and its molecular weight is 120.19 g/mol. It boils at 165 °C, melts at -44.8 °C, is miscible with water.
Under the GHS it carries the signal word Warning.
Other names for Mesitylene
- 1,3,5-trimethylbenzene
02 · GHS classification
Hazards and label elements
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
| Code | Hazard statement |
|---|---|
| H226 | Flammable liquid and vapour. |
| H335 | May cause respiratory irritation. |
| H411 | Toxic to aquatic life with long lasting effects. |
Precautionary statements: P210, P233, P241, P242, P273, P391, P403, P501
03 · Physical and chemical properties
Mesitylene properties
Every value is shown with the conditions it was measured under and the source it came from. Where sources disagree, all values are listed rather than one being picked — the difference is usually a different form of the substance, not an error.
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 164.7 °C (328.5 °F) | at 760 mmHg | HSDB |
| 165 °C (329 °F) | NIOSH | ||
| 165 °C (329 °F) | at 760 mmHg | CAMEO | |
| Melting point | -44.8 °C (-48.6 °F) | HSDB | |
| -45 °C (-49 °F) | NIOSH | ||
| Density | 0.86 g/cm³ | NIOSH | |
| 0.8637 g/cm³ | at 20 °C | HSDB | |
| Solubility | Miscible with alcohol, ether, benzene | HSDB | |
| Miscible in ethanol, ethyl ether, acetone | HSDB | ||
| Miscible with oxygenated and aromatic solvents. | HSDB | ||
| Vapor pressure | 2 mmHg | NIOSH | |
| 1.86 mmHg | at 20 °C | HSDB | |
| 2.48 mmHg | at 25 °C | HSDB | |
| Flash point | 50 °C (122 °F) | Closed cup | HSDB |
| 50 °C (122 °F) | NIOSH | ||
| Autoignition temperature | 559.44 °C (1039 °F) | HSDB | |
| 550 °C (1022 °F) | ICSC | ||
| Lower explosive limit (LEL) | Class II Flammable Liquid | NIOSH | |
| Vapor density | 4.1 (air = 1) | ICSC | |
| 1.006 (air = 1) | at 20 °C | HSDB | |
| Odor threshold | Odor Threshold Low: 2.0 [ppm] | Haz-Map | |
| Odor threshold (recognition) from CHEMINFO | Haz-Map | ||
| Critical temperature and pressure | 364.36 °C (687.8 °F) | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
04 · Fire and explosion
Fire and explosion behaviour of Mesitylene
These are descriptions rather than measured values, so they are kept out of the table above and quoted here with the source that reported them.
Fire and explosion
... RISK OF... EXPLOSION REQUIRES THAT CONCN OF VAPOR IN ATMOSPHERE IS KEPT BELOW 35-50 PPM BY MEANS OF EFFECTIVE VENTILATION OR, PREFERABLY, LOCAL APPLIED EXHAUST VENTILATION. /TRIMETHYLBENZENES/
Source: HSDB
05 · Handling and storage
Storing and handling Mesitylene
Storage conditions
Prior to working with this chemical you should be trained on its proper handling and storage. This chemical must be stored to avoid contact with oxidizers (such as perchlorates, peroxides, permanganates, chlorates, and nitrates), and strong oxidizers (such as chlorine, bromine, and fluorine) since violent reactions occur. Store in tightly closed containers in a cool, well-ventilated area away from heat. Sources of ignition such as smoking and open flames are prohibited where this chemical is used, handled, or stored in a manner that could create a potential fire or explosion hazard. Metal containers involving the transfer of 5 gallons or more of this chemical should be grounded and bonded. Drums must be equipped with self-closing valves, pressure vacuum bungs, and flame arresters. Use only nonsparking tools and equipment, especially when opening and closing containers of this chemical.
Source: Hazardous Substances Data Bank (HSDB)
Incompatible materials
Forms explosive mixture with air. Strong oxidizers cause fire and explosion hazard. Violent reaction with nitric acid.
Source: Hazardous Substances Data Bank (HSDB)
Reactivity
1,3,5-TRIMETHYLBENZENE is incompatible with the following: Oxidizers, nitric acid (NIOSH, 2024).
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Mesitylene in the storage compatibility matrix →