Substance profile
Trimethyl borate
Trimethyl borate is colorless, moisture-sensitive liquid; fumes in air.
01 · Identification
What Trimethyl borate is
Trimethyl borate is colorless, moisture-sensitive liquid; fumes in air. It boils at 67.5 °C, melts at -29.3 °C.
Under the GHS it carries the signal word Danger. It is classed as flammable agents - 3rd degree.
02 · Identifiers
Trimethyl borate identifiers and molecular data
Trimethyl borate CAS number and EC number
Trimethyl borate molecular formula and molecular weight
03 · GHS classification
Trimethyl borate hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Trimethyl borate pictograms and signal word
Trimethyl borate hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Flammable liquids GHS chapter 2.6 | Category 3 | H226 | GHS02 |
| Acute toxicity - dermal GHS chapter 3.1 | Category 4 | H312 | GHS07 |
Trimethyl borate hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H226 | Flammable liquid and vapour. |
| H360FD | May damage fertility. May damage the unborn child. |
| H312 | Harmful in contact with skin. |
This page lists only the codes assigned to Trimethyl borate. 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 Trimethyl borate
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 Trimethyl borate 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
Trimethyl borate precautionary statements
CLP Annex VI assigns 9 precautionary statements to Trimethyl borate. 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.
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
Trimethyl borate name in 22 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 | триметилов борат |
| Spanish español | Borato de trimetilo |
| Czech čeština | trimethyl-borát |
| Danish dansk | trimethylborat |
| German Deutsch | Trimethylborat |
| Estonian eesti | trimetüülboraat |
| Greek ελληνικά | βορικός τριμεθυλεστέρας |
| English English | trimethyl borate |
| French français | borate de triméthyle |
| Croatian hrvatski | trimetil-borat |
| Italian italiano | trimetil borato |
| Latvian latviešu | trimetilborāts |
| Lithuanian lietuvių | trimetilboratas |
| Hungarian magyar | trimetil-borát |
| Maltese Malti | borat tat-trimetil |
| Dutch Nederlands | trimethylboraat |
| Portuguese português | borato de trimetilo |
| Romanian română | borat de trimetil |
| Slovak slovenčina | trimetyl-borát |
| Slovenian slovenščina | trimetil borat |
| Finnish suomi | trimetyyliboraatti |
| Swedish svenska | trimetylborat |
22 of the 23 language editions carry this entry; it is absent from Polish. That is a property of the regulation, not a gap in this table — editions do occasionally differ in which entries they print. 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
Trimethyl borate GHS label elements
Everything CLP Annex VI fixes for Trimethyl borate, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Trimethyl borate
- Flammable liquid and vapour.
- May damage fertility. May damage the unborn child.
- Harmful in contact with skin.
- 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.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF ON SKIN:
- Call a POISON CENTER/doctor/… if you feel unwell.
- Wash with plenty of water/…
- Store in a well-ventilated place.
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Trimethyl borate in the GHS label constructor →
07 · Health hazards
Trimethyl borate health hazards and exposure limits
Trimethyl borate hazard summary
A skin and eye irritant; Inhalation may cause cough and sore throat; [ICSC] Chronic poisoning in grazing animals where soil is high in boric acid results in vomiting, diarrhea, shock, convulsions, and paralysis; Post-mortem findings include inflammation of the GI tract, liver and kidney damage, and cerebral edema; [HSDB]
Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
08 · Physical and chemical properties
Trimethyl borate 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.
Trimethyl borate boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 67.5 °C (153.5 °F) | HSDB | |
| 68 °C (154.4 °F) | ICSC | ||
| 68 °C (154.4 °F) | at 760 mmHg | DOE PAC |
Trimethyl borate melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -29.3 °C (-20.7 °F) | HSDB | |
| -29 °C (-20.2 °F) | ICSC |
Trimethyl borate density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 0.915 g/cm³ | HSDB | |
| 0.92 g/cm³ | at 20 °C | DOE PAC |
Trimethyl borate solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Miscible with tetrahydrofuran, ether, isoporpylamine, hexane, methanol, nujol, and other organic liquids | HSDB | |
| Miscible with alcohol, ether; soluble in polar nonhydroxylic solvents | HSDB | ||
| Solubility in water: reaction | ICSC |
Trimethyl borate vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 137 mmHg | at 25 °C | HSDB |
| 135.011 mmHg | at 25 °C | ICSC |
Trimethyl borate flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 7 °C (44.6 °F) | ICSC | |
| 26.67 °C (80 °F) | below this value | HSDB |
Trimethyl borate lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | Reacts with oxidants causing fire and explosion hazard. | table | HSDB |
Trimethyl borate vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 3.59 (air = 1) | HSDB | |
| 3.6 (air = 1) | ICSC |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Trimethyl borate 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.
Trimethyl borate fire potential
Flammable, fire risk ...
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Trimethyl borate storage and handling
Trimethyl borate safe storage
Fireproof. Separated from strong oxidants and strong acids. Dry.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Trimethyl borate incompatible materials
... Reacts with water and oxidizing agents.
Source: Hazardous Substances Data Bank (HSDB)
Trimethyl borate reactivity
Borates, such as TRIMETHYL BORATE, behave similarly to esters in that they react with acids to liberate heat along with alcohols and acids. Strong oxidizing acids may cause a vigorous reaction that is sufficiently exothermic to ignite the reaction products. Heat is also generated by the interaction of esters with caustic solutions. Flammable hydrogen is generated by mixing esters/borates with alkali metals and hydrides.
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Trimethyl borate in the storage compatibility matrix →
11 · Transport
Trimethyl borate 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.
Trimethyl borate under UN 2416 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| TRIMETHYL BORATE | 3 | F1 | II | |
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) |
|---|---|---|---|
| Trimethyl borate | 3 | II | |
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
Trimethyl borate — frequently asked questions
What is the CAS number of Trimethyl borate?
The CAS number of Trimethyl borate is 121-43-7. Its EC number is 204-468-9.
What does a Trimethyl borate label have to show?
Under CLP Annex VI the label for Trimethyl borate carries the pictograms Flame, Health hazard and Exclamation mark and the signal word is Danger.
Is Trimethyl borate flammable?
Yes. CLP Annex VI assigns Trimethyl borate H226 — flammable liquid and vapour. The flash point reported for it is 7 °C (44.6 °F) (ICSC).
Is Trimethyl borate a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Trimethyl borate. 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 Trimethyl borate?
The boiling point reported for Trimethyl borate is 67.5 °C (153.5 °F) (HSDB).
What is the melting point of Trimethyl borate?
The melting point reported for Trimethyl borate is -29.3 °C (-20.7 °F) (HSDB).
How should Trimethyl borate be stored?
CLP Annex VI assigns Trimethyl borate the storage statement P403.
Nearby
Substances next to Trimethyl borate
Keep going: substances starting with T, or search the whole database by name, CAS number, pictogram or signal word.