Substance profile
Benzidine
Benzidine is a white or slightly-reddish, crystalline powder.
01 · Identification
What Benzidine is
Benzidine is a white or slightly-reddish, crystalline powder. Its molecular formula is C12H12N2 and its molecular weight is 184.24 g/mol. It boils at 401 °C, melts at 120 °C.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
02 · Identifiers
Benzidine identifiers and molecular data
Benzidine CAS number and EC number
Benzidine molecular formula and molecular weight
Other names for Benzidine
- 1,1'-biphenyl-4,4'-diamine
- 4,4'-diaminobiphenyl
- biphenyl-4,4'-ylenediamine
03 · GHS classification
Benzidine hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Benzidine pictograms and signal word
Benzidine hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Acute toxicity - oral GHS chapter 3.1 | Category 4 | H302 | GHS07 |
| Carcinogenicity GHS chapter 3.6 | Category 1A or 1B | H350 | GHS08 |
| Hazardous to the aquatic environment - acute GHS chapter 4.1 | Category 1 | H400 | GHS09 |
| Hazardous to the aquatic environment - chronic GHS chapter 4.1 | Category 1 | H410 | GHS09 |
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.
Benzidine 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>. |
| H302 | Harmful if swallowed. |
| H400 | Very toxic to aquatic life. |
| H410 | Very toxic to aquatic life with long lasting effects. |
This page lists only the codes assigned to Benzidine. 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 Benzidine
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 Benzidine 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
Benzidine precautionary statements
CLP Annex VI assigns 11 precautionary statements to Benzidine. 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.
Disposal
What has to happen to the contents and the empty container.
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
Benzidine 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 | бензидин 1,1′-бифенил-4,4′-диамин4,4′-диаминобифенилбифенил-4,4′-илендиамин |
| Spanish español | Bencidina 1,1'-bifenil-4,4'-diamina4,4'-diaminobifenilobifenil-4,4'-ilendiamina |
| Czech čeština | benzidin bifenyl-4,4'-diamin4,4'- diaminobifenylbifenyl-4,4'-ylendiamin |
| Danish dansk | benzidin 1,1'-biphenyl-4,4'-diamin 4,4'-diaminobiphenylbiphenyl-4,4'-ylendiamin |
| German Deutsch | Benzidin 1,1'-Biphenyl-4,4'-diamin4,4'-DiaminobiphenylBiphenyl-4,4'-ylendiamin |
| Estonian eesti | bensidiin 1,1'-bifenüül-4,4'-diamiin4,4′-diaminobifenüül4,4'-bifenüleendiamiin |
| Greek ελληνικά | βενζιδίνη 1,1′-διφαινυλο-4,4′-διαμίνη4,4′-διαμινοδιφαινύλιοδιφαινυλ-4,4′-υλενοδιαμίνη |
| English English | benzidine 1,1'-biphenyl-4,4'-diamine4,4'-diaminobiphenylbiphenyl-4,4'-ylenediamine |
| French français | benzidine 1,1'-biphényl-4,4'-diamine4,4'-diaminobiphénylebiphényle-4,4'-ylènediamine |
| Croatian hrvatski | benzidin 1,1'-bifenil-4,4'-diamin4,4'-diaminobifenilbifenil-4,4'-ilendiamin |
| Italian italiano | benzidina 1,1'-bifenil-4,4' diamina4,4'-diaminobifenile |
| Latvian latviešu | benzidīns 1,1'-bifenil-4,4'-diamīns4,4'-diaminobifenilsbifenil-4,4'-ilēndiamīns |
| Lithuanian lietuvių | benzidinas 1,1'-bifenil-4,4'-diaminas4,4'-diaminobifenilasbifenil-4,4'-ilendiaminas |
| Hungarian magyar | benzidin 1,1’-bifenil-4,4’-diamin4,4’-diaminobifenilbifenil-4,4’-iléndiamin |
| Maltese Malti | benżidina 1,1'-bifenil-4,4'-diammina4,4'-diamminobifenilbifenil-4,4'-ilendiammina |
| Dutch Nederlands | benzidine 1,1'-bifenyl-4,4'-diamine4,4'-diaminobifenylbifenyl-4,4'-yleendiamine |
| Polish polski | benzydyna 1,1'-bifenylo-4,4'-diaminabifenylo-4,4'-diaminabifenyl-4,4'-ylenodiamina |
| Portuguese português | benzidina 1,1'-bifenil-4,4'-diamina4,4'-diaminobifenilobifenil-4,4'-ilenodiamina |
| Romanian română | benzidină 1,1'-bifenil-4,4'-diamină4,4'-diaminobifenilbifenil-4,4'-ilendiamină |
| Slovak slovenčina | benzidín bifenyl-4,4'-diamín4,4'-diaminobifenylbifenyl-4,4'-yléndiamín |
| Slovenian slovenščina | benzidin 1,1'-bifenil-4,4'-diamin4,4'-diaminobifenilbifenil-4,4'-ilendiamin |
| Finnish suomi | bentsidiini 1,1′-bifenyyli-4,4′-diamiini4,4'-diaminobifenyylibifenyl-4,4′-yleenidiamiini |
| Swedish svenska | bensidin 1,1'-bifenyl-4,4'-diamin4,4'-diaminobifenylbifenyl-4,4'-ylendiamin |
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
Benzidine GHS label elements
Everything CLP Annex VI fixes for Benzidine, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Benzidine
- May cause cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>.
- Harmful if swallowed.
- Very toxic to aquatic life.
- Very toxic to aquatic life with long lasting effects.
- Obtain special instructions before use.
- Do not eat, drink or smoke when using this product.
- Avoid release to the environment.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF SWALLOWED:
- IF exposed or concerned:
- Call a POISON CENTER/doctor/… if you feel unwell.
- Get medical advice/attention.
- Rinse mouth.
- Collect spillage.
- Dispose of contents/container to …
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Benzidine in the GHS label constructor →
07 · Health hazards
Benzidine health hazards and exposure limits
Benzidine hazard summary
Benzidine is a manufactured chemical that does not occur naturally. It is a crystalline solid that may be grayish-yellow, white, or reddish-gray. In the environment, benzidine is found in either its "free" state (as an organic base), or as a salt. Benzidine was used to produce dyes for cloth, paper, and leather. It is no longer produced or used commerically in the U.S.
Source: Agency for Toxic Substances and Disease Registry (ATSDR)
Benzidine carcinogenicity classification
CLASSIFICATION: A; human carcinogen. BASIS FOR CLASSIFICATION: Observation of increased incidence of bladder cancer and bladder cancer-related deaths in exposed workers. HUMAN CARCINOGENICITY DATA: Sufficient.
Source: Hazardous Substances Data Bank (HSDB)
Sufficient evidence of carcinogenicity in humans. Sufficient evidence of carcinogenicity in animals. OVERALL EVALUATION: Group 1: The agent is carcinogenic 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.
Benzidine occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | [1910.1010] See Appendix BSee Appendix C | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | Ca See Appendix ASee Appendix C | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | A potential occupational carcinogen. (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | NIOSH considers benzidine to be a potential occupational carcinogen. | Hazardous Substances Data Bank (HSDB) |
| IDLH | Ca [N.D.] | The National Institute for Occupational Safety and Health (NIOSH) |
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
Benzidine 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.
Benzidine boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 401 °C (753.8 °F) | HSDB | |
| 400 °C (752 °F) | NIOSH | ||
| 400 °C (752 °F) | at 740 mmHg | CAMEO |
Benzidine melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 120 °C (248 °F) | HSDB | |
| 115 °C (239 °F) | NIOSH | ||
| 127.78 °C (262 °F) | CAMEO |
Benzidine density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 1.25 g/cm³ | NIOSH | |
| 1.25 g/cm³ | at 20 °C | HSDB | |
| 2.15 g/cm³ | at 20 °C | CAMEO |
Benzidine solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | 1 g dissolves in 2500 ml cold water; 1 g dissolves in 107 ml boiling water; 1 g dissolves in 5 ml boiling alcohol; 1 g dissolves in 50 ml ether | HSDB | |
| less than 1 mg/mL at 72 °F (NTP, 1992) | at 22.22 °C | CAMEO | |
| In water, 322 mg/l @ 25 °C | at 25 °C | HSDB |
Benzidine vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 9e-7 mmHg | Haz-Map | |
| Low | NIOSH | ||
| Low (NIOSH, 2024) | CAMEO |
Benzidine lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | Combustible Solid, but difficult to burn. | NIOSH |
Benzidine vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 6.36 (air = 1) | HSDB | |
| 6.4 (air = 1) | ICSC |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Benzidine 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.
Benzidine fire potential
Benzidine itself does not burn or burns with difficulty.
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Benzidine storage and handling
Benzidine safe storage
Provision to contain effluent from fire extinguishing. Separated from strong oxidants and food and feedstuffs. Keep in the dark. Well closed. Store in an area without drain or sewer access.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Benzidine storage conditions
KEEP WELL CLOSED & PROTECTED FROM LIGHT.
Source: Hazardous Substances Data Bank (HSDB)
Benzidine incompatible materials
Benzidine is hypergolic (will ignite spontaneously) with red fuming nitric acid.
Source: Hazardous Substances Data Bank (HSDB)
Benzidine reactivity
BENZIDINE forms insoluble salts with sulfuric acid. Can be diazotized, acetylated and alkylated. Is hypergolic with red fuming nitric acid (NTP, 1992). Neutralizes acids in exothermic reactions to form salts plus water. May be incompatible with isocyanates, halogenated organics, peroxides, phenols (acidic), epoxides, anhydrides, and acid halides. Flammable gaseous hydrogen may be generated in combination with strong reducing agents, such as hydrides.
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Benzidine in the storage compatibility matrix →
11 · Transport
Benzidine 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.
Benzidine under UN 1885 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| BENZIDINE | 6.1 | T2 | II | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 6.1 is “Toxic substances” (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) |
|---|---|---|---|
| Benzidine | 6.1 | II | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 6.1 is “Poisonous materials” (49 CFR 173.2).
12 · Questions
Benzidine — frequently asked questions
What is the CAS number of Benzidine?
The CAS number of Benzidine is 92-87-5. Its EC number is 202-199-1.
What is the chemical formula of Benzidine?
The molecular formula of Benzidine is C12H12N2 and its molecular weight is 184.24 g/mol.
What does a Benzidine label have to show?
Under CLP Annex VI the label for Benzidine carries the pictograms Health hazard, Exclamation mark and Environment and the signal word is Danger.
Is Benzidine flammable?
CLP Annex VI assigns Benzidine 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.
Is Benzidine a carcinogen?
Yes. CLP Annex VI classifies Benzidine as a category 1A or 1B carcinogen and assigns it H350: may cause cancer. IARC places it in Group 1: carcinogenic to humans.
What is the exposure limit for Benzidine?
The US occupational exposure limit reported for Benzidine is [1910.1010] See Appendix BSee Appendix C (The National Institute for Occupational Safety and Health (NIOSH)). 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 Benzidine?
The boiling point reported for Benzidine is 401 °C (753.8 °F) (HSDB).
What is the melting point of Benzidine?
The melting point reported for Benzidine is 120 °C (248 °F) (HSDB).
How should Benzidine be stored?
KEEP WELL CLOSED & PROTECTED FROM LIGHT. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Benzidine
Keep going: substances starting with B, or search the whole database by name, CAS number, pictogram or signal word.