Provenance

Reference data from EU CLP Annex VI and published regulations — verify against your supplier's SDS before use.

Build a label

Substance profile

1,3,5-Trioxane

1,3,5-Trioxane is a crystalline solid with a characteristic chloroform-like odor.

CAS 110-88-3 C3H6O3 90.08 g/mol Danger

01 · Identification

What 1,3,5-Trioxane is

1,3,5-Trioxane is a crystalline solid with a characteristic chloroform-like odor. Its molecular formula is C3H6O3 and its molecular weight is 90.08 g/mol. It boils at 115 °C, melts at 64 °C.

Under the GHS it carries the signal word Danger.

02 · Identifiers

1,3,5-Trioxane identifiers and molecular data

1,3,5-Trioxane CAS number and EC number

CAS number110-88-3
EC number203-812-5
Index number (CLP Annex VI)605-002-00-0

1,3,5-Trioxane molecular formula and molecular weight

Molecular formulaC3H6O3
Molecular weight90.08 g/mol

Other names for 1,3,5-Trioxane

  • 1,3,5-trioxan
  • trioxymethylene

03 · GHS classification

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.

1,3,5-Trioxane pictograms and signal word

Signal wordDanger

1,3,5-Trioxane hazard class and category

GHS hazard classes 1,3,5-Trioxane falls into
Hazard class Category From code Pictogram
Flammable solids GHS chapter 2.7 Category 1 or 2 H228 GHS02
Specific target organ toxicity - single exposure GHS chapter 3.8 Category 3 H335 GHS07

Where two values are shown with “or”, the hazard statement is shared by more than one category or by more than one class, and the code alone does not say which. H272, for example, belongs to oxidising liquids and to oxidising solids — the physical state decides. The binding answer for a specific entry is in the CLP Annex VI table itself.

1,3,5-Trioxane hazard statements (H-codes)

Hazard statements assigned to 1,3,5-Trioxane
CodeHazard statement
H228 Flammable solid.
H361d Suspected of damaging the unborn child.
H335 May cause respiratory irritation.

This page lists only the codes assigned to 1,3,5-Trioxane. 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 1,3,5-Trioxane

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 1,3,5-Trioxane 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

1,3,5-Trioxane precautionary statements

CLP Annex VI assigns 4 precautionary statements to 1,3,5-Trioxane. 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.

Response

What to do once exposure, spillage or fire has already happened.

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

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 1,3,5-триоксан триоксиметилен
Spanish español 1,3,5-Trioxano trioximetileno
Czech čeština 1,3,5-trioxan trioxymethylen
Danish dansk 1,3,5-trioxan trioxymethylen
German Deutsch 1,3,5-Trioxan Trioxymethylen
Estonian eesti 1,3,5-trioksaan trioksümetüleen
Greek ελληνικά 1,3,5-τριοξάνιο τριοξυμεθυλένιο
English English 1,3,5-trioxan trioxymethylene
French français 1,3,5-trioxane trioxyméthylène
Croatian hrvatski 1,3,5-trioksan trioksimetilen
Italian italiano 1,3,5-triossano triossimetilene
Latvian latviešu 1,3,5-trioksāns trioksimetilēns
Lithuanian lietuvių 1,3,5-trioksanas trioksimetilenas
Hungarian magyar 1,3,5-trioxán trioximetilén
Maltese Malti 1,3,5-triossan triossimetilen
Dutch Nederlands 1,3,5-trioxaan trioxymethyleen
Polish polski 1,3,5-trioksan trioksymetylen
Portuguese português 1,3,5-trioxano trioximetileno
Romanian română 1,3,5-trioxan trioximetilen
Slovak slovenčina 1,3,5-trioxán trioxymetylén
Slovenian slovenščina 1,3,5-trioksan trioksimetilen
Finnish suomi 1,3,5-trioksaani trioksimetyleeni
Swedish svenska 1,3,5-trioxan trioximetylen

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

1,3,5-Trioxane GHS label elements

Everything CLP Annex VI fixes for 1,3,5-Trioxane, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.

GHS02 Flame pictogramGHS08 Health hazard pictogramGHS07 Exclamation mark pictogram

Danger

1,3,5-Trioxane

  • Flammable solid.
  • Suspected of damaging the unborn child.
  • May cause respiratory irritation.
  • Obtain special instructions before use.
  • Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/
  • IF exposed or concerned:
  • Get medical advice/attention.

Supplier name, address and telephone number· Product identifier·Nominal quantity

Need this as an actual label? Open 1,3,5-Trioxane in the GHS label constructor →

07 · Health hazards

1,3,5-Trioxane health hazards and exposure limits

1,3,5-Trioxane hazard summary

Cyclic trimer of formaldehyde; [Merck Index] A respiratory tract irritant; [eChemPortal: ESIS] Slowly releases formaldehyde at body temperature; Has same toxicity as formaldehyde after absorption into the body; [HSDB] A respiratory tract irritant; A severe skin and eye irritant; [MSDSonline] See Formaldehyde.

Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases

08 · Physical and chemical properties

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.

1,3,5-Trioxane boiling point

Property Value Conditions Source
Boiling point 114.5 °C (238.1 °F) at 759 mmHg HSDB

1,3,5-Trioxane melting point

Property Value Conditions Source
Melting point 64 °C (147.2 °F) HSDB
63.89 °C (147 °F) CAMEO

1,3,5-Trioxane density

Property Value Conditions Source
Density 1.17 g/cm³ at 65 °C HSDB

1,3,5-Trioxane solubility

Property Value Conditions Source
Solubility SOL IN BENZENE, CARBON TETRACHLORIDE, CHLOROFORM, CARBON DISULFIDE HSDB
greater than or equal to 100 mg/mL at 68 °F (NTP, 1992) at 20 °C CAMEO

1,3,5-Trioxane vapor pressure

Property Value Conditions Source
Vapor pressure 13 mmHg at 25 °C CAMEO
13 mmHg Haz-Map

1,3,5-Trioxane flash point

Property Value Conditions Source
Flash point 45 °C (113 °F) HSDB

1,3,5-Trioxane autoignition temperature

Property Value Conditions Source
Autoignition temperature 413.89 °C (777 °F) HSDB

1,3,5-Trioxane lower explosive limit (LEL)

Property Value Conditions Source
Lower explosive limit (LEL) 3.6 % by volume CAMEO
EXPLOSIVE LIMITS IN AIR 3.5-29%. HSDB

1,3,5-Trioxane upper explosive limit (UEL)

Property Value Conditions Source
Upper explosive limit (UEL) 28.7 % by volume CAMEO

1,3,5-Trioxane vapor density

Property Value Conditions Source
Vapor density 3.1 (air = 1) CAMEO

Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.

09 · Fire and explosion

1,3,5-Trioxane 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.

1,3,5-Trioxane fire potential

MODERATE FIRE RISK.

Source: Hazardous Substances Data Bank (HSDB)

Solubility

SOL IN WATER: 17.2 G/100 ML @ 18 °C, 21.2 @ 25 °C; EASILY SOL IN ALC, KETONES, ETHER, ACETONE, ORG SOLVENTS, CHLORINATED & AROMATIC HYDROCARBONS; SLIGHTLY SOL IN PENTANE, PETROLEUM ETHER, LOWER PARAFFINS

Source: HSDB

10 · Handling and storage

1,3,5-Trioxane storage and handling

1,3,5-Trioxane peroxide formation

D*: Other compounds that may form peroxides

Source: Lab and Research Safety, University of Minnesota

1,3,5-Trioxane storage conditions

STORE IN COOL, DRY, WELL-VENTILATED PLACE AWAY FROM SOURCES OF HEAT & IGNITION. SEPARATE FROM COMBUSTIBLES, & ACIDIC, ALKALINE, & OXIDIZING MATERIALS. /PARAFORMALDEHYDE/

Source: Hazardous Substances Data Bank (HSDB)

1,3,5-Trioxane reactivity

1,3,5-TRIOXANE is stable under normal laboratory conditions but is unstable in the presence of acids, which initiate polymerization. Sublimes readily. May react with oxidizing matter (NTP, 1992). A stable polymeric product of formaldehyde that in the presence of strong aqueous acids will depolymerize (reforming the parent formaldehyde). Inert to strong alkalis. Readily converted in non aqueous solutions to the monomeric formaldehyde by small concentrations of acid---the rate of conversion is directly proportional to the concentration of the acid.

Source: CAMEO Chemicals

Planning storage for a mix of chemicals? Check 1,3,5-Trioxane in the storage compatibility matrix →

11 · Questions

1,3,5-Trioxane — frequently asked questions

What is the CAS number of 1,3,5-Trioxane?

The CAS number of 1,3,5-Trioxane is 110-88-3. Its EC number is 203-812-5.

What is the chemical formula of 1,3,5-Trioxane?

The molecular formula of 1,3,5-Trioxane is C3H6O3 and its molecular weight is 90.08 g/mol.

What does a 1,3,5-Trioxane label have to show?

Under CLP Annex VI the label for 1,3,5-Trioxane carries the pictograms Flame, Health hazard and Exclamation mark and the signal word is Danger.

Is 1,3,5-Trioxane flammable?

Yes. CLP Annex VI assigns 1,3,5-Trioxane H228 — flammable solid. The flash point reported for it is 45 °C (113 °F) (HSDB).

Is 1,3,5-Trioxane a carcinogen?

CLP Annex VI records no harmonised carcinogenicity classification for 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 1,3,5-Trioxane?

The boiling point reported for 1,3,5-Trioxane is 114.5 °C (238.1 °F), at 759 mmHg (HSDB).

What is the melting point of 1,3,5-Trioxane?

The melting point reported for 1,3,5-Trioxane is 64 °C (147.2 °F) (HSDB).

How should 1,3,5-Trioxane be stored?

STORE IN COOL, DRY, WELL-VENTILATED PLACE AWAY FROM SOURCES OF HEAT & IGNITION. SEPARATE FROM COMBUSTIBLES, & ACIDIC, ALKALINE, & OXIDIZING MATERIALS. /PARAFORMALDEHYDE/ (Hazardous Substances Data Bank (HSDB))

Get the free GHS / CLP / OSHA deadline calendar

Verified 2026–2029 compliance dates in one PDF — plus alerts when the rules change.