Substance profile
Diazomethane
Diazomethane is a yellow gas with a musty odor.
01 · Identification
What Diazomethane is
Diazomethane is a yellow gas with a musty odor. It boils at -23 °C, melts at -145 °C.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
02 · Identifiers
Diazomethane identifiers and molecular data
Diazomethane CAS number and EC number
Diazomethane molecular formula and molecular weight
03 · GHS classification
Diazomethane hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Diazomethane pictograms and signal word
Diazomethane hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Carcinogenicity GHS chapter 3.6 | Category 1A or 1B | H350 | GHS08 |
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.
Diazomethane hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H350 | May cause cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>. |
This page lists only the codes assigned to Diazomethane. 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 Diazomethane
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 Diazomethane 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
Diazomethane precautionary statements
CLP Annex VI assigns 4 precautionary statements to Diazomethane. 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
Diazomethane 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 | диазометан |
| Spanish español | Diazometano |
| Czech čeština | diazomethan |
| Danish dansk | diazomethan |
| German Deutsch | Diazomethan |
| Estonian eesti | diasometaan |
| Greek ελληνικά | διαζωμεθάνιο |
| English English | diazomethane |
| French français | diazométhane |
| Croatian hrvatski | diazometan |
| Italian italiano | diazometano |
| Latvian latviešu | diazometāns |
| Lithuanian lietuvių | diazometanas |
| Hungarian magyar | diazometán |
| Maltese Malti | diażometan |
| Dutch Nederlands | diazomethaan |
| Polish polski | diazometan |
| Portuguese português | diazometano |
| Romanian română | diazometan |
| Slovak slovenčina | diazometán |
| Slovenian slovenščina | diazometan |
| Finnish suomi | diatsometaani |
| Swedish svenska | diazometan |
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
Diazomethane GHS label elements
Everything CLP Annex VI fixes for Diazomethane, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Diazomethane
- May cause cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>.
- 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 Diazomethane in the GHS label constructor →
07 · Health hazards
Diazomethane health hazards and exposure limits
Diazomethane hazard summary
The major source of exposure to diazomethane is occupational. Diazomethane is a strong respiratory irritant. Acute (short-term) inhalation exposure of humans to diazomethane may cause irritation of the eyes, cough, wheezing, asthmatic symptoms, pulmonary edema, pneumonia, dizziness, weakness, headache, and chest pains. No information is available on the chronic (long-term), reproductive, developmental, or carcinogenic effects of diazomethane in humans. Increased incidences of lung tumors have been observed in rats and mice exposed to diazomethane by inhalation and in dermally exposed mice. EPA has not classified diazomethane with respect to its potential carcinogenicity.
Source: EPA Hazardous Air Pollutants
Diazomethane carcinogenicity classification
No data are available in humans. Limited evidence of carcinogenicity in animals. OVERALL EVALUATION: Group 3: The agent is not classifiable as to its carcinogenicity to humans.
Source: Hazardous Substances Data Bank (HSDB)
An IARC group and a CLP classification answer different questions. IARC judges whether the evidence for cancer in humans is strong enough; CLP Annex VI is the legally binding EU classification. A substance can carry one and not the other.
Diazomethane occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 0.2 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | 0.2 ppm (0.4 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| PEL | TWA 0.2 ppm (0.4 mg/m3) | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | 0.2 ppm (0.4 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| REL | TWA 0.2 ppm (0.4 mg/m3) | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 2 ppm (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 2.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| IDLH | 2 ppm | Hazardous Substances Data Bank (HSDB) |
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
Diazomethane 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.
Diazomethane boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | -23 °C (-9.4 °F) | HSDB | |
| -22.78 °C (-9 °F) | NIOSH | ||
| -22.78 °C (-9 °F) | at 760 mmHg | CAMEO |
Diazomethane melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -145 °C (-229 °F) | HSDB |
Diazomethane density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 1.45 g/cm³ | HSDB | |
| 1.45 g/cm³ | at 25 °C | DOE PAC |
Diazomethane solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Soluble in ... benzene, alcohol | HSDB | |
| Very soluble in ether and dioxane | HSDB | ||
| Decomposes in water | decomposes | HSDB |
Diazomethane vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 3900 mmHg | at 25 °C | ICSC |
| 760 mmHg | above this value | NIOSH |
Diazomethane flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | NA (Gas) | NIOSH | |
| Flammable gas | ICSC |
Diazomethane autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 100 °C (212 °F) | HSDB | |
| 100 °C (212 °F) | explosion | ICSC |
Diazomethane vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 1.45 (air = 1) | HSDB | |
| 1.4 (air = 1) | ICSC |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Diazomethane 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.
Fire and explosion
... MAY EXPLODE VIOLENTLY ON HEATING OR IN CONTACT WITH ROUGH SURFACES. IN ETHER OR BENZENE, IN WHICH DIAZOMETHANE IS SOL, THE DANGER OF EXPLOSION IS MUCH DECREASED.
Source: HSDB
CALCIUM SULFATE IS UNSUITABLE DESICCANT FOR DRYING-TUBES IN DIAZOMETHANE SYSTEMS. CONTACT OF DIAZOMETHANE VAPOR & SULFATE CAUSES EXOTHERM WHICH MAY LEAD TO DETONATION.
Source: HSDB
DIAZOMETHANE WILL UNDERGO VIOLENT THERMAL DECOMP. ABOVE 200 °C, VAPOR MAY EXPLODE VIOLENTLY. EXPLOSIONS AT LOW TEMPERATURES CAN OCCUR IF TRACES OF ORGANIC MATTER ARE PRESENT.
Source: HSDB
10 · Handling and storage
Diazomethane storage and handling
Diazomethane safe storage
Solutions of diazomethane should not be stored.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Diazomethane storage conditions
Diazomethane should be stored in a cool, dry, well-ventilated area in tightly sealed containers that are labeled in accordance with OSHA's Hazard Communication Standard. Containers of diazomethane should be protected from shock, heat, sparks, open flames and physical damage and should be stored separately from alkali metals, calcium sulfate, calcium chloride, boiling stones, or copper powder. Outside or detached storage is preferred. Empty containers of diazomethane should be handled appropriately.
Source: Hazardous Substances Data Bank (HSDB)
Diazomethane incompatible materials
Contact between diazomethane and alkali metals, calcium sulfate, calcium chloride, boiling stones, or copper powder will cause explosions.
Source: Hazardous Substances Data Bank (HSDB)
Diazomethane reactivity
DIAZOMETHANE undergoes violent thermal decomposition. Above 200 °C. the vapors may explode violently if rough glass surfaces are present. Explosions at low temperatures can occur if traces of organic matter are present. [J. Phys. Chem. 35:1403(1931)]. Produces explosions with alkali metals. Reacts with copper powder and to some extent all solid surfaces to produce nitrogen and solid white polymethylene. Reacts with dimethylaminodimethylarsine and trimethyltin in ether with vigorous foaming.
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Diazomethane in the storage compatibility matrix →
11 · Questions
Diazomethane — frequently asked questions
What is the CAS number of Diazomethane?
The CAS number of Diazomethane is 334-88-3. Its EC number is 206-382-7.
What does a Diazomethane label have to show?
Under CLP Annex VI the label for Diazomethane carries the pictogram Health hazard and the signal word is Danger.
Is Diazomethane flammable?
CLP Annex VI assigns Diazomethane no flammability hazard class. That is not a statement that it cannot burn: the harmonised list only records the hazards that were assessed for it. The flash point reported for it is NA (Gas) (NIOSH).
Is Diazomethane a carcinogen?
Yes. CLP Annex VI classifies Diazomethane as a category 1A or 1B carcinogen and assigns it H350: may cause cancer. IARC places it in Group 3: not classifiable as to its carcinogenicity to humans.
What is the exposure limit for Diazomethane?
The US occupational exposure limit reported for Diazomethane is 0.2 [ppm] (Haz-Map, Information on Hazardous Chemicals and Occupational Diseases). 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 Diazomethane?
The boiling point reported for Diazomethane is -23 °C (-9.4 °F) (HSDB).
What is the melting point of Diazomethane?
The melting point reported for Diazomethane is -145 °C (-229 °F) (HSDB).
How should Diazomethane be stored?
Diazomethane should be stored in a cool, dry, well-ventilated area in tightly sealed containers that are labeled in accordance with OSHA's Hazard Communication Standard. Containers of diazomethane should be protected from shock, heat, sparks, open flames and physical damage and should be stored separately from alkali metals, calcium sulfate, calcium chloride, boiling stones, or copper powder. Outside or detached storage is preferred. Empty containers of diazomethane should be handled appropriately. (Hazardous Substances Data Bank (HSDB))
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