UN 2078 — Toluene diisocyanate
Placard: Toxic. ERG Guide 156. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2078 is Toluene diisocyanate, a toxic isocyanate liquid assigned to ERG Guide 156. Inhalation can cause severe respiratory sensitization and water contact can generate CO2 pressure.
Hazard overview: TOXIC isocyanate liquid; inhalation of vapor or aerosol may cause severe respiratory sensitization and injury. Combustible material: may burn but does not ignite readily. Reacts with water slowly, producing carbon dioxide and heat; pressure buildup may occur in closed containers.
Response guidance: For a UN 2078 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 156. Establish incident command, isolate the area, stay upwind, control ignition or incompatibility hazards, prevent runoff or vapor spread and base entry/fire-control actions on monitoring and local SOP.
Firefighter training notes: Training for UN 2078 should emphasize exposure routes, air monitoring, PPE selection, fire behavior, decontamination, runoff containment and ERG/SDS verification. Use ERG 156, SDS and local SOP.
Regulatory context: Toluene diisocyanate is regulated as a hazardous material for transportation and emergency response purposes. Storage, workplace exposure, emergency planning, spill reporting, waste handling and environmental requirements vary by exact product, concentration, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, container markings and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Toluene diisocyanate should be stored in tightly closed compatible containers in a secure, ventilated toxic/corrosive area with secondary containment, restricted access and segregation from incompatible chemicals according to SDS.
UN 2078 Quick Details
Common Hazards of UN 2078
- TOXIC isocyanate liquid; inhalation of vapor or aerosol may cause severe respiratory sensitization and injury.
- Combustible material: may burn but does not ignite readily.
- Reacts with water slowly, producing carbon dioxide and heat; pressure buildup may occur in closed containers.
- Vapors are heavier than air and may collect in low or confined areas.
- Skin and eye contact may cause irritation or burns and sensitization.
- Fire may produce nitrogen oxides, isocyanate vapors, hydrogen cyanide-type products and other toxic gases.
- Runoff may spread toxic isocyanate contamination.
Chemical Identity & Physical Properties
Clear to pale yellow liquid with a sharp, pungent odor. Commercially available as a mixture of 2,4- and 2,6-isomers.
| Also known as | TDI2,4-Toluene diisocyanateMethylbenzene diisocyanateDiisocyanatotolueneHylene T |
| CAS Number | 584-84-9 |
| Appearance | Clear to pale yellow liquid with a sharp, pungent odor. Commercially available as a mixture of 2,4- and 2,6-isomers. |
| Flash Point | 127C (260F) |
| Boiling Point | 251C (484F) |
| Vapor Density | 6.0 (heavier than air) |
| Water Reactivity | Reacts slowly with water producing carbon dioxide and heat. May generate toxic fumes. Avoid water contact. |
Fireground Response Guidance — UN 2078
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for dust, vapor, mist, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing selected from SDS; avoid skin contact.
Isolation & Evacuation
First Actions for a UN 2078 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Avoid breathing vapors, gas, dust, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled/released material unless properly trained and wearing appropriate protective equipment.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or release area and expand the perimeter for fire involvement, vapor spread, gas accumulation, cylinder heating or unknown product identity.
- Use ERG Guide 156, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2078 — Toluene diisocyanateUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.