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.
02 · Identifiers
Mesitylene identifiers and molecular data
Mesitylene CAS number and EC number
Mesitylene molecular formula and molecular weight
Other names for Mesitylene
- 1,3,5-trimethylbenzene
03 · GHS classification
Mesitylene hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Mesitylene pictograms and signal word
Mesitylene hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Flammable liquids GHS chapter 2.6 | Category 3 | H226 | GHS02 |
| Specific target organ toxicity - single exposure GHS chapter 3.8 | Category 3 | H335 | GHS07 |
| Hazardous to the aquatic environment - chronic GHS chapter 4.1 | Category 2 | H411 | GHS09 |
Mesitylene hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H226 | Flammable liquid and vapour. |
| H335 | May cause respiratory irritation. |
| H411 | Toxic to aquatic life with long lasting effects. |
This page lists only the codes assigned to Mesitylene. The full reference lives on the hazard statements hub, the precautionary statements hub and the GHS pictograms hub.
Safety Data Sheet
Getting an SDS for Mesitylene
A Safety Data Sheet is written for a product, not for a substance: the supplier of the grade you actually buy issues it, so two suppliers of Mesitylene issue two different sheets. That is why there is no single authoritative SDS for a substance to download — what there is, is the job of collecting the sheets for the products you hold and keeping them current as suppliers revise them.
04 · Precautionary statements
Mesitylene precautionary statements
CLP Annex VI assigns 8 precautionary statements to Mesitylene. They are grouped the way a label groups them: what to do before handling, what to do when something has already happened, how to store it and how to dispose of it.
Prevention
What to do before and during handling so the hazard never happens.
Disposal
What has to happen to the contents and the empty container.
Reading the notation. … is a blank the supplier fills in — not a truncated sentence.· [square brackets] mark a part printed only when it applies.
05 · Names in the regulation
Mesitylene name in 23 EU languages
CLP Annex VI Part 3 is published in every language edition of the regulation, and the identification column is written out in each of them. Nothing below is translated by us: each line is the name as that edition prints it. Under Art. 18(2) the substance name from Annex VI is a lawful product identifier, so this is the wording to put on a label going to that market — and where the cell lists several designations, any one of them qualifies.
| Language | Name in CLP Annex VI Part 3 |
|---|---|
| Bulgarian български | мезитилен 1,3,5-триметилбензен |
| Spanish español | Mesitileno 1,3,5-trimetilbenceno |
| Czech čeština | mesitylen 1,3,5-trimethylbenzen |
| Danish dansk | mesitylen 1,3,5-trimethylbenzen |
| German Deutsch | Mesitylen 1,3,5-Trimethylbenzol |
| Estonian eesti | mesitüleen 1,3,5-trimetüülbenseen |
| Greek ελληνικά | μεσιτυλένιο 1,3,5-τριμεθυλοβενζόλιο |
| English English | mesitylene 1,3,5-trimethylbenzene |
| French français | mésitylène 1,3,5-triméthylbenzène |
| Croatian hrvatski | mezitilen 1,3,5-trimetilbenzen |
| Italian italiano | mesitilene 1,3,5-trimetilbenzene |
| Latvian latviešu | mezitilēns 1,3,5-trimetilbenzols |
| Lithuanian lietuvių | mezitilenas 1,3,5-trimetilbenzenas |
| Hungarian magyar | mezitilén 1,3,5-trimetilbenzol |
| Maltese Malti | mesitilen 1,3,5-trimetilbenżen |
| Dutch Nederlands | mesityleen 1,3,5-trimethylbenzeen |
| Polish polski | mezytylen 1,3,5-trimetylobenzen |
| Portuguese português | mesitileno 1,3,5-trimetilbenzeno |
| Romanian română | mesitilen 1,3,5-trimetilbenzen |
| Slovak slovenčina | mezitylén 1,3,5-trimetylbenzén |
| Slovenian slovenščina | mezitilen 1,3,5-trimetilbenzen |
| Finnish suomi | mesityleeni 1,3,5-trimetyylibentseeni |
| Swedish svenska | mesitylen 1,3,5-trimetylbensen |
All 23 language editions of Annex VI carry this entry. Irish is the twenty-fourth official EU language and has no line here for a different reason: no consolidated CLP text has ever been published in Irish, so there is no Irish edition of Annex VI to quote a name from. Source: consolidated CLP, CELEX 02008R1272, language editions. © European Union, https://eur-lex.europa.eu — only the electronic Official Journal of the European Union is authentic.
06 · Label elements
Mesitylene GHS label elements
Everything CLP Annex VI fixes for Mesitylene, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Warning
Mesitylene
- Flammable liquid and vapour.
- May cause respiratory irritation.
- Toxic to aquatic life with long lasting effects.
- Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
- Keep container tightly closed.
- Use explosion-proof [electrical/ventilating/lighting/…] equipment.
- Use only non-sparking tools.
- Avoid release to the environment.
- Collect spillage.
- Store in a well-ventilated place.
- Dispose of contents/container to …
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Mesitylene in the GHS label constructor →
07 · Health hazards
Mesitylene health hazards and exposure limits
Mesitylene hazard summary
A skin, eye, nose, throat and respiratory tract irritant; [Merck Index] A skin, eye, and respiratory tract irritant; Defats the skin; May have effects on the central nervous system and blood; [ICSC] A skin, eye, and respiratory tract irritant; [HSDB] A nose, throat, and lung irritant; Inhalation of high concentrations can cause CNS depression; [CHEMINFO] A respiratory tract irritant; [eChemPortal: ESIS] See Trimethyl benzene isomers.
Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
Mesitylene occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | none See Appendix G | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | TWA 25 ppm (125 mg/m3) | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | N.D. | The National Institute for Occupational Safety and Health (NIOSH) |
These are United States values. The European Union sets its own indicative and binding limits, and the figure that applies at a given workplace is the one in the local regulation — not the one shown here.
08 · 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.
Mesitylene boiling point
| 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 |
Mesitylene melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -44.8 °C (-48.6 °F) | HSDB | |
| -45 °C (-49 °F) | NIOSH |
Mesitylene density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 0.86 g/cm³ | NIOSH | |
| 0.8637 g/cm³ | at 20 °C | HSDB |
Mesitylene solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Miscible with alcohol, ether, benzene | HSDB | |
| Miscible in ethanol, ethyl ether, acetone | HSDB | ||
| Miscible with oxygenated and aromatic solvents. | HSDB |
Mesitylene vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 2 mmHg | NIOSH | |
| 1.86 mmHg | at 20 °C | HSDB | |
| 2.48 mmHg | at 25 °C | HSDB |
Mesitylene flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 50 °C (122 °F) | Closed cup | HSDB |
| 50 °C (122 °F) | NIOSH |
Mesitylene autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 559.44 °C (1039 °F) | HSDB | |
| 550 °C (1022 °F) | ICSC |
Mesitylene lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | Class II Flammable Liquid | NIOSH |
Mesitylene vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 4.1 (air = 1) | ICSC | |
| 1.006 (air = 1) | at 20 °C | HSDB |
Mesitylene odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | Odor Threshold Low: 2.0 [ppm] | Haz-Map | |
| Odor threshold (recognition) from CHEMINFO | Haz-Map |
Mesitylene critical temperature and pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| 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.
09 · Fire and explosion
Mesitylene fire and explosion behaviour
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.
Mesitylene fire potential
MODERATE, VIA HEAT, FLAMES, OXIDIZERS
Source: Hazardous Substances Data Bank (HSDB)
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
10 · Handling and storage
Mesitylene storage and handling
Mesitylene safe storage
Fireproof. Separated from strong oxidants. Well closed. Keep in a well-ventilated room.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
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)
Mesitylene 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)
Mesitylene 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 →
11 · Questions
Mesitylene — frequently asked questions
What is the CAS number of Mesitylene?
The CAS number of Mesitylene is 108-67-8. Its EC number is 203-604-4.
What is the chemical formula of Mesitylene?
The molecular formula of Mesitylene is C9H12 and its molecular weight is 120.19 g/mol.
What does a Mesitylene label have to show?
Under CLP Annex VI the label for Mesitylene carries the pictograms Flame, Exclamation mark and Environment and the signal word is Warning.
Is Mesitylene flammable?
Yes. CLP Annex VI assigns Mesitylene H226 — flammable liquid and vapour. The flash point reported for it is 50 °C (122 °F), Closed cup (HSDB).
Is Mesitylene a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Mesitylene. Annex VI is a list of agreed classifications, not a list of substances found safe, so this is an absence of a classification rather than a clean bill of health.
What is the exposure limit for Mesitylene?
The US occupational exposure limit reported for Mesitylene is none See Appendix G (The National Institute for Occupational Safety and Health (NIOSH)). Limits differ by country: the EU sets its own indicative and binding values, and the figure that applies at a given workplace is the one in the local regulation.
What is the boiling point of Mesitylene?
The boiling point reported for Mesitylene is 164.7 °C (328.5 °F), at 760 mmHg (HSDB).
What is the melting point of Mesitylene?
The melting point reported for Mesitylene is -44.8 °C (-48.6 °F) (HSDB).
How should Mesitylene be stored?
CLP Annex VI assigns Mesitylene the storage statement P403. 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. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Mesitylene
Keep going: substances starting with M, or search the whole database by name, CAS number, pictogram or signal word.