Substance profile
Pyridine
Pyridine is a colorless to yellow liquid with a sharp, nauseating odor.
01 · Identification
What Pyridine is
Pyridine is a colorless to yellow liquid with a sharp, nauseating odor. Its molecular formula is C5H5N and its molecular weight is 79.1 g/mol. It boils at 116 °C, melts at -41.6 °C, is miscible with water.
Under the GHS it carries the signal word Danger. It is classed as flammable agents - 3rd degree.
02 · Identifiers
Pyridine identifiers and molecular data
Pyridine CAS number and EC number
Pyridine molecular formula and molecular weight
Other names for Pyridine
- Azabenzene
- Azine
- Cp 32
03 · GHS classification
Pyridine hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Pyridine pictograms and signal word
Pyridine hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Flammable liquids GHS chapter 2.6 | Category 2 | H225 | GHS02 |
| Acute toxicity - oral GHS chapter 3.1 | Category 4 | H302 | GHS07 |
| Acute toxicity - dermal GHS chapter 3.1 | Category 4 | H312 | GHS07 |
| Acute toxicity - inhalation GHS chapter 3.1 | Category 4 | H332 | GHS07 |
Pyridine hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H225 | Highly flammable liquid and vapour. |
| H332 | Harmful if inhaled. |
| H312 | Harmful in contact with skin. |
| H302 | Harmful if swallowed. |
This page lists only the codes assigned to Pyridine. 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 Pyridine
Our own Pyridine safety data sheet walks through all sixteen sections of the published data. What it is not is the document an inspector asks for: an SDS is issued for a product by its supplier, so the sheet covering the grade actually standing in your store exists only in that supplier’s version. Collecting those and keeping them current as suppliers revise them is a separate job.
04 · Precautionary statements
Pyridine precautionary statements
CLP Annex VI assigns 15 precautionary statements to Pyridine. 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
Pyridine 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 | пиридин |
| Spanish español | Piridina |
| Czech čeština | pyridin |
| Danish dansk | pyridin |
| German Deutsch | Pyridin |
| Estonian eesti | püridiin |
| Greek ελληνικά | πυριδίνη |
| English English | pyridine |
| French français | pyridine |
| Croatian hrvatski | piridin |
| Italian italiano | piridina |
| Latvian latviešu | piridīns |
| Lithuanian lietuvių | piridinas |
| Hungarian magyar | piridin |
| Maltese Malti | piridina |
| Dutch Nederlands | pyridine |
| Polish polski | pirydyna |
| Portuguese português | piridina |
| Romanian română | piridină |
| Slovak slovenčina | pyridín |
| Slovenian slovenščina | piridin |
| Finnish suomi | pyridiini |
| Swedish svenska | pyridin |
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
Pyridine GHS label elements
Everything CLP Annex VI fixes for Pyridine, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Pyridine
- Highly flammable liquid and vapour.
- Harmful if inhaled.
- Harmful in contact with skin.
- Harmful if swallowed.
- 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.
- Do not breathe dust/fume/gas/mist/vapours/spray.
- Do not eat, drink or smoke when using this product.
- Use only outdoors or in a well-ventilated area.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF SWALLOWED:
- IF ON SKIN:
- IF INHALED:
- Call a POISON CENTER/doctor/… if you feel unwell.
- Rinse mouth.
- 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 Pyridine in the GHS label constructor →
07 · Health hazards
Pyridine health hazards and exposure limits
Pyridine hazard summary
Pyridine is a colorless liquid with an unpleasant smell. It can be made from crude coal tar or from other chemicals. Pyridine is used to dissolve other substances. It is also used to make many different products such as medicines, vitamins, food flavorings, paints, dyes, rubber products, adhesives, insecticides, and herbicides. Pyridine can also be formed from the breakdown of many natural materials in the environment.
Source: Agency for Toxic Substances and Disease Registry (ATSDR)
Pyridine carcinogenicity classification
Under the conditions of these 2-year drinking water studies, there was some evidence of carcinogenic activity of pyridine in male F344/N rats based on increased incidences of renal tubule neoplasms. There was equivocal evidence of carcinogenic activity of pyridine in female F344/N rats based on increased incidences of mononuclear cell leukemia. There was equivocal evidence of carcinogenic activity in male Wistar rats based on an increased incidence of interstitial cell adenoma of the testis. There was clear evidence of carcinogenic activity of pyridine in male and female B6C3F1 mice based on increased incidences of malignant hepatocellular neoplasms.
Source: US National Toxicology Program · TR-470: Toxicology and Carcinogenesis Studies of Pyridine (CASRN 110-86-1) in F344/N Rats, Wistar Rats, and B6C3F1 Mice (Drinking Water Studies) (2000 )
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.
Pyridine occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 5.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | 5 ppm (15 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| PEL | TWA 5 ppm (15 mg/m3) | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | 5 ppm (15 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| REL | TWA 5 ppm (15 mg/m3) | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 1000 ppm (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 1000.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| IDLH | 1000 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
Pyridine 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.
Pyridine boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 115.56 °C (240 °F) | NIOSH | |
| 115 °C (239 °F) | at 760 mmHg | CAMEO | |
| 115 °C (239 °F) | ICSC |
Pyridine melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -41.6 °C (-42.9 °F) | HSDB | |
| -42.22 °C (-44 °F) | NIOSH |
Pyridine density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 0.98 g/cm³ | NIOSH | |
| 0.9827 g/cm³ | at 20 °C | HSDB | |
| 0.983 g/cm³ | at 20 °C | CAMEO |
Pyridine solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Miscible with ... alcohol, ether, and petroleum ether, oils and many organic liquids. | HSDB | |
| Miscible | NIOSH | ||
| Miscible with water @ 20 °C | at 20 °C | HSDB |
Pyridine vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 16 mmHg | NIOSH | |
| 18 mmHg | at 20 °C | CAMEO | |
| 20.8 mmHg | at 25 °C | HSDB |
Pyridine flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 20 °C (68 °F) | HSDB | |
| 20 °C (68 °F) | closed cup | HSDB |
Pyridine autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 482 °C (899.6 °F) | HSDB | |
| 482.22 °C (900 °F) | CAMEO |
Pyridine lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 1.8 % by volume | HSDB |
Pyridine upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | 12.4 % by volume | HSDB |
Pyridine vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 0.982 (air = 1) | HSDB | |
| 2.72 (air = 1) | CAMEO | ||
| 2.73 (air = 1) | ICSC |
Pyridine odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | Water odor threshold: 0.95 mg/l; Air odor threshold: 0.17 ul/l; Odor safety class: B. B= 50-90% of distracted persons perceive warning of TLV. | HSDB | |
| Odor detection in water is 8.20x10+1 ppm; chemically pure | HSDB | ||
| Odor recognition in air is 2.10x10-2 ppm; chemically pure | HSDB |
Pyridine critical temperature and pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Critical temperature and pressure | 346.78 °C (656.2 °F) | HSDB |
Pyridine corrosivity
| Property | Value | Conditions | Source |
|---|---|---|---|
| Corrosivity | Liquid pyridine will attack some forms of plastics, rubber and coatings. | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Pyridine 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.
Pyridine fire potential
Pyridine is a flammable ... liquid.
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Pyridine storage and handling
Pyridine reactive group
CAMEO Chemicals places Pyridine in the reactive group Amines, Phosphines, and Pyridines. Compatibility with other chemicals is worked out from the group, not from the individual substance — which is why two substances you have never seen react can still be flagged as a pair that must be separated.
A reactive group is a CAMEO Chemicals (US NOAA) grouping, not a GHS hazard class: it has no code, no category and no legal force. It is what the storage compatibility matrix on this site computes from.
Pyridine safe storage
Store only in original container. Fireproof. Separated from strong oxidants and strong acids. Cool. Dry. Well closed. Store in an area without drain or sewer access.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Pyridine storage conditions
OUTSIDE OR DETACHED STORAGE IS PREFERABLE. ISOLATE FROM POWERFUL OXIDIZING MATERIALS AND ACIDS.
Source: Hazardous Substances Data Bank (HSDB)
Pyridine incompatible materials
PYRIDINE REACTS VIOLENTLY WITH CHLOROSULFONIC ACID, CHROMIC ACID, MALEIC ANHYDRIDE, NITRIC ACID, FUMING SULFURIC ACID, PERCHROMATES, BETA-PROPIOLACTONE, SILVER PERCHLORATE, & SULFURIC ACID.
Source: Hazardous Substances Data Bank (HSDB)
Planning storage for a mix of chemicals? Check Pyridine in the storage compatibility matrix →
11 · Transport
Pyridine 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.
Pyridine under UN 1282 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| PYRIDINE | 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) |
|---|---|---|---|
| Pyridine | 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
Pyridine — frequently asked questions
What is the CAS number of Pyridine?
The CAS number of Pyridine is 110-86-1. Its EC number is 203-809-9.
What is the chemical formula of Pyridine?
The molecular formula of Pyridine is C5H5N and its molecular weight is 79.1 g/mol.
What does a Pyridine label have to show?
Under CLP Annex VI the label for Pyridine carries the pictograms Flame and Exclamation mark and the signal word is Danger.
Is Pyridine flammable?
Yes. CLP Annex VI assigns Pyridine H225 — highly flammable liquid and vapour. The flash point reported for it is 20 °C (68 °F) (HSDB).
Is Pyridine a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Pyridine. 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. IARC places it in Group 2B: possibly carcinogenic to humans.
What is the exposure limit for Pyridine?
The US occupational exposure limit reported for Pyridine is 5.0 [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 Pyridine?
The boiling point reported for Pyridine is 115.56 °C (240 °F) (NIOSH).
What is the melting point of Pyridine?
The melting point reported for Pyridine is -41.6 °C (-42.9 °F) (HSDB).
How should Pyridine be stored?
CLP Annex VI assigns Pyridine the storage statement P403. OUTSIDE OR DETACHED STORAGE IS PREFERABLE. ISOLATE FROM POWERFUL OXIDIZING MATERIALS AND ACIDS. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Pyridine
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