UN 1780 — Fumaryl chloride
Placard: Corrosive. ERG Guide 156. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1780 is Fumaryl chloride, a toxic corrosive acid chloride assigned to ERG Guide 156. It fumes in moist air and can release heat plus dense hydrogen chloride fumes.
Hazard overview: UN 1780 presents corrosive vapor, toxic exposure, water-reaction and combustible liquid hazards. Avoid water contact with product and contain acidic runoff.
Response guidance: For a UN 1780 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 156. Establish incident command, isolate the area, stay upwind, prevent incompatible contact, control runoff and choose entry or fire-control actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1780 should emphasize corrosive exposure routes, water or oxidizer incompatibility where applicable, air monitoring, PPE selection, decontamination and runoff containment. Use ERG 156, SDS and local SOP.
Regulatory context: Fumaryl chloride is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by concentration, formulation, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Fumaryl chloride should be stored in tightly closed compatible containers in a cool, dry, well-ventilated area away from water, moisture, bases, oxidizers/reducing agents where incompatible, heat and unauthorized access. Protect containers from corrosion, leakage and contamination.
UN 1780 Quick Details
Common Hazards of UN 1780
- TOXIC and CORROSIVE acid chloride; inhalation, ingestion or skin/eye contact may cause severe injury.
- Reacts with water or moist air, releasing heat and corrosive hydrogen chloride fumes.
- Combustible liquid: may burn under fire conditions.
- Vapors are heavier than air and may collect in low or confined areas.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff may spread toxic and corrosive contamination.
- Containers may rupture or fail when heated or contaminated with water.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a pungent, acrid odor. Fumes in moist air due to hydrolysis.
| Also known as | Fumaroyl dichlorideFumaric acid dichloridetrans-1,2-Ethylenedicarboxylic acid dichloride2-Butenedioyl dichloride |
| CAS Number | 627-63-4 |
| Appearance | Colorless to pale yellow liquid with a pungent, acrid odor. Fumes in moist air due to hydrolysis. |
| Flash Point | 102C (216F) |
| Boiling Point | 160C (320F) with decomposition |
| Vapor Density | 5.3 (much heavier than air) |
| Water Reactivity | Reacts violently with water producing hydrochloric acid and fumaric acid; avoid water contact |
Fireground Response Guidance — UN 1780
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fume, fire or confined-space exposure. Chemical-resistant gloves, boots, eye/face protection and protective clothing should be selected from SDS; Level A may be needed for close entry or unknown concentrations.
Isolation & Evacuation
First Actions for a UN 1780 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, fumes, dust, mist or spray and avoid skin or eye contact.
- Keep water and moisture away from released product unless incident command confirms a compatible cooling or control use.
- Do not touch or walk through spilled 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 leak area and expand the perimeter if vapor, dust, fire involvement, water reaction or unknown concentration is present.
- Use ERG Guide 156, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1780 — Fumaryl chlorideUse 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.