Substance profile
2,4,6-trimethyl-1,3,5-trioxane
2,4,6-trimethyl-1,3,5-trioxane is colorless, transparent liquid with a characteristic aromatic odor.
01 · Identification
What 2,4,6-trimethyl-1,3,5-trioxane is
2,4,6-trimethyl-1,3,5-trioxane is colorless, transparent liquid with a characteristic aromatic odor. It boils at 125 °C, melts at 12.6 °C.
Under the GHS it carries the signal word Warning. It is classed as flammable agents - 3rd degree.
02 · Identifiers
2,4,6-trimethyl-1,3,5-trioxane identifiers and molecular data
2,4,6-trimethyl-1,3,5-trioxane CAS number and EC number
2,4,6-trimethyl-1,3,5-trioxane molecular formula and molecular weight
Other names for 2,4,6-trimethyl-1,3,5-trioxane
- paraldehyde
03 · GHS classification
2,4,6-trimethyl-1,3,5-trioxane hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
2,4,6-trimethyl-1,3,5-trioxane pictograms and signal word
2,4,6-trimethyl-1,3,5-trioxane hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Flammable liquids GHS chapter 2.6 | Category 3 | H226 | GHS02 |
2,4,6-trimethyl-1,3,5-trioxane hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H226 | Flammable liquid and vapour. |
This page lists only the codes assigned to 2,4,6-trimethyl-1,3,5-trio…. 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 2,4,6-trimethyl-1,3,5-trio…
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 2,4,6-trimethyl-1,3,5… 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
2,4,6-trimethyl-1,3,5-trioxane precautionary statements
CLP Annex VI assigns 5 precautionary statements to 2,4,6-trimethyl-1,3,5-trio…. 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.
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
2,4,6-trimethyl-1,3,5-trioxane 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 | 2,4,6-триметил-1,3,5-триоксан паралдехид |
| Spanish español | 2,4,6-Trimetil-1,3,5-trioxane paraldehído |
| Czech čeština | 2,4,6-trimethyl-1,3,5-trioxan paraldehyd |
| Danish dansk | 2,4,6-trimethyl-1,3,5-trioxan paraldehyd |
| German Deutsch | 2,4,6-Trimethyl-1,3,5-trioxan Paraldehyd |
| Estonian eesti | 2,4,6-trimetüül-1,3,5-trioksaan paraldehüüd |
| Greek ελληνικά | 2,4,6-τριμεθυλο-1,3,5-τριοξάνιο παραλδεΰδη |
| English English | 2,4,6-trimethyl-1,3,5-trioxane paraldehyde |
| French français | 2,4,6-triméthyl-1,3,5-trioxane paraldéhyde |
| Croatian hrvatski | 2,4,6-trimetil-1,3,5-trioksan paraldehid |
| Italian italiano | 2,4,6-trimetil-1,3,5-triossano paraldeide |
| Latvian latviešu | 2,4,6-trimetil-1,3,5-trioksāns paraldehīds |
| Lithuanian lietuvių | 2,4,6-trimetil-1,3,5-trioksanas paraldehidas |
| Hungarian magyar | 2,4,6-trimetil-1,3,5-trioxán paraldehid |
| Maltese Malti | 2,4,6-trimetil-1,3,5-triossan paraldeid |
| Dutch Nederlands | 2,4,6-trimethyl-1,3,5-trioxaan paraldehyde |
| Polish polski | 2,4,6-trimetylo-1,3,5-trioksan paraldehyd |
| Portuguese português | 2,4,6-trimetil-1,3,5-trioxano paraldeído |
| Romanian română | 2,4,6-trimetil-1,3,5-trioxan paraldehidă |
| Slovak slovenčina | 2,4,6-trimetyl-1,3,5-trioxán paraldehyd |
| Slovenian slovenščina | 2,4,6-trimetil-1,3,5-trioksan paraldehid |
| Finnish suomi | 2,4,6-trimetyyli-1,3,5-trioksaani paraldehydi |
| Swedish svenska | 2,4,6-trimetyl-1,3,5-trioxan paraldehyd |
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
2,4,6-trimethyl-1,3,5-trioxane GHS label elements
Everything CLP Annex VI fixes for 2,4,6-trimethyl-1,3,5-trio…, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Warning
2,4,6-trimethyl-1,3,5-trioxane
- Flammable liquid and vapour.
- 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.
- Store in a well-ventilated place.
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open 2,4,6-trimethyl-1,3,5-trio… in the GHS label constructor →
07 · Health hazards
2,4,6-trimethyl-1,3,5-trioxane health hazards and exposure limits
2,4,6-trimethyl-1,3,5-trioxane hazard summary
A skin, eye, and respiratory tract irritant; Causes sedation and respiratory depression when ingested; May cause injury to the liver and kidneys; [ICSC] A severe eye irritant; Targets CNS, heart, lungs, liver, and kidneys; [MSDSonline]
Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
08 · Physical and chemical properties
2,4,6-trimethyl-1,3,5-trioxane 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.
2,4,6-trimethyl-1,3,5-trioxane boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 124.5 °C (256.1 °F) | HSDB | |
| 127.78 °C (262 °F) | at 760 mmHg | CAMEO |
2,4,6-trimethyl-1,3,5-trioxane melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 12.6 °C (54.7 °F) | HSDB | |
| 12.61 °C (54.7 °F) | CAMEO |
2,4,6-trimethyl-1,3,5-trioxane density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 0.9923 g/cm³ | at 20 °C | HSDB |
| 0.991 g/cm³ | at 20 °C | HSDB | |
| 0.9943 g/cm³ | at 20 °C | CAMEO |
2,4,6-trimethyl-1,3,5-trioxane solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Sol in water: 1 in 9 parts at 20 °C, 1 in 10 parts at 30 °C, & 1 in 11.5 parts at 37 °C | at 20 °C | HSDB |
| Sol in sodium chloride solution: 1 in 9.5 parts at 20 °C, 1 in 11 parts at 30 °C, & 1 in 12.5 parts at 37 °C | at 20 °C | HSDB | |
| SOL IN 8 PARTS WATER AT 25 °C; 17 PARTS BOILING WATER | at 25 °C | HSDB |
2,4,6-trimethyl-1,3,5-trioxane vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 25.3 mmHg | at 20 °C | HSDB |
| 7.5006 mmHg | at 20 °C | ICSC | |
| 7.5 mmHg | at 17 °C | DOE PAC |
2,4,6-trimethyl-1,3,5-trioxane flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 35.56 °C (96 °F) | HSDB | |
| 24 °C (75.2 °F) | ICSC |
2,4,6-trimethyl-1,3,5-trioxane autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 237.78 °C (460 °F) | HSDB | |
| 235 °C (455 °F) | ICSC |
2,4,6-trimethyl-1,3,5-trioxane lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 1.3 % by volume | HSDB |
2,4,6-trimethyl-1,3,5-trioxane upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | 17 % by volume | ICSC |
2,4,6-trimethyl-1,3,5-trioxane vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 4.5 (air = 1) | HSDB |
2,4,6-trimethyl-1,3,5-trioxane odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | 0.02-0.025 mg/cu m (recognition) | HSDB |
2,4,6-trimethyl-1,3,5-trioxane critical temperature and pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Critical temperature and pressure | 290 °C (554 °F) | HSDB |
2,4,6-trimethyl-1,3,5-trioxane corrosivity
| Property | Value | Conditions | Source |
|---|---|---|---|
| Corrosivity | ... Has solvent action upon rubber, polystyrene, & styrene-acrylonitrile copolymer | like | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
2,4,6-trimethyl-1,3,5-trio… 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.
2,4,6-trimethyl-1,3,5-trioxane fire potential
DANGEROUS, WHEN EXPOSED TO HEAT, FLAME OR OXIDIZERS.
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
2,4,6-trimethyl-1,3,5-trioxane storage and handling
2,4,6-trimethyl-1,3,5-trioxane safe storage
Fireproof. Separated from food and feedstuffs, bases and oxidants.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
2,4,6-trimethyl-1,3,5-trioxane storage conditions
PARALDEHYDE SHOULD BE STORED IN WELL-FILLED, TIGHT, LIGHT-RESISTANT GLASS CONTAINERS WITH A CAPACITY OF NO MORE THAN 30 ML, AT A TEMP NOT EXCEEDING 25 °C.
Source: Hazardous Substances Data Bank (HSDB)
2,4,6-trimethyl-1,3,5-trioxane incompatible materials
Paraldehyde is incompatible with many plastics
Source: Hazardous Substances Data Bank (HSDB)
2,4,6-trimethyl-1,3,5-trioxane reactivity
PARALDEHYDE is an ether derivative. This compound is decomposed by light and air, on prolonged storage, to acetaldehyde and acetic acid. Incompatible with alkalis, hydrocyanic acid iodides and oxidizers. (NTP, 1992)
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check 2,4,6-trimethyl-1,3,5-tri… in the storage compatibility matrix →
11 · Transport
2,4,6-trimethyl-1,3,5-trioxane UN number and transport classification
Transport classification is a separate system from the GHS classification above. It decides how a package is marked and how a load may be carried; it does not follow from the workplace label, and the workplace label does not follow from it. The entries below are linked by CAS number, never by name.
2,4,6-trimethyl-1,3,5-trioxane under UN 1264 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| PARALDEHYDE | 3 | F1 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 3 is “Flammable liquids” (ADR 2.1.1.1).
United States · 49 CFR 172.101 Hazardous Materials Table
| Proper shipping name (column 2) | Class or division | PG | Labels (column 6) |
|---|---|---|---|
| Paraldehyde | 3 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 3 is “Flammable and combustible liquid” (49 CFR 173.2).
12 · Questions
2,4,6-trimethyl-1,3,5-trioxane — frequently asked questions
What is the CAS number of 2,4,6-trimethyl-1,3,5-trioxane?
The CAS number of 2,4,6-trimethyl-1,3,5-trioxane is 123-63-7. Its EC number is 204-639-8.
What does a 2,4,6-trimethyl-1,3,5-trioxane label have to show?
Under CLP Annex VI the label for 2,4,6-trimethyl-1,3,5-trioxane carries the pictogram Flame and the signal word is Warning.
Is 2,4,6-trimethyl-1,3,5-trioxane flammable?
Yes. CLP Annex VI assigns 2,4,6-trimethyl-1,3,5-trioxane H226 — flammable liquid and vapour. The flash point reported for it is 35.56 °C (96 °F) (HSDB).
Is 2,4,6-trimethyl-1,3,5-trioxane a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for 2,4,6-trimethyl-1,3,5-trioxane. 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 boiling point of 2,4,6-trimethyl-1,3,5-trioxane?
The boiling point reported for 2,4,6-trimethyl-1,3,5-trioxane is 124.5 °C (256.1 °F) (HSDB).
What is the melting point of 2,4,6-trimethyl-1,3,5-trioxane?
The melting point reported for 2,4,6-trimethyl-1,3,5-trioxane is 12.6 °C (54.7 °F) (HSDB).
How should 2,4,6-trimethyl-1,3,5-trioxane be stored?
CLP Annex VI assigns 2,4,6-trimethyl-1,3,5-trioxane the storage statement P403. PARALDEHYDE SHOULD BE STORED IN WELL-FILLED, TIGHT, LIGHT-RESISTANT GLASS CONTAINERS WITH A CAPACITY OF NO MORE THAN 30 ML, AT A TEMP NOT EXCEEDING 25 °C. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to 2,4,6-trimethyl-1,3,5-trio…
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