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).
Other names for Benzidine
- 1,1'-biphenyl-4,4'-diamine
- 4,4'-diaminobiphenyl
- biphenyl-4,4'-ylenediamine
02 · GHS classification
Hazards and label elements
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
| 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. |
Precautionary statements: P201, P270, P273, P280, P301, P308, P312, P313, P330, P391, P501
03 · 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.
| 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 | |
| Melting point | 120 °C (248 °F) | HSDB | |
| 115 °C (239 °F) | NIOSH | ||
| 127.78 °C (262 °F) | CAMEO | ||
| Density | 1.25 g/cm³ | NIOSH | |
| 1.25 g/cm³ | at 20 °C | HSDB | |
| 2.15 g/cm³ | at 20 °C | CAMEO | |
| 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 | |
| Vapor pressure | 9e-7 mmHg | Haz-Map | |
| Low | NIOSH | ||
| Low (NIOSH, 2024) | CAMEO | ||
| Lower explosive limit (LEL) | Combustible Solid, but difficult to burn. | NIOSH | |
| 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.
04 · Handling and storage
Storing and handling Benzidine
Storage conditions
KEEP WELL CLOSED & PROTECTED FROM LIGHT.
Source: Hazardous Substances Data Bank (HSDB)
Incompatible materials
Benzidine is hypergolic (will ignite spontaneously) with red fuming nitric acid.
Source: Hazardous Substances Data Bank (HSDB)
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 →