UN 2496 — Propionic anhydride
Placard: Corrosive. ERG Guide 156. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2496 is Propionic anhydride, a corrosive combustible anhydride assigned to ERG Guide 156. Water reaction produces heat and propionic acid.
Hazard overview: CORROSIVE combustible organic anhydride; inhalation or skin/eye contact may cause severe irritation or burns. Reacts with water to release heat and propionic acid; large quantities can react vigorously. Vapors are heavier than air and may form explosive mixtures when heated.
Response guidance: For UN 2496, isolate the area, avoid skin contact and use SCBA where vapor, dust, mist or fire is present. Contain toxic/corrosive runoff and verify product controls with SDS and ERG 156.
Firefighter training notes: Training for UN 2496 should emphasize toxic/corrosive exposure routes, skin absorption, SCBA use, decontamination, runoff containment and SDS verification. Use ERG 156, SDS and local SOP.
Regulatory context: Propionic anhydride is regulated as a hazardous material for transport and emergency response. Storage, exposure, spill reporting, waste and fire-code duties depend on quantity, concentration and jurisdiction; verify shipping papers, SDS and local authority requirements.
Storage & handling: Propionic anhydride should be stored in tightly closed compatible containers with ventilation, secondary containment, restricted access and SDS-based segregation from incompatible materials.
UN 2496 Quick Details
Common Hazards of UN 2496
- CORROSIVE combustible organic anhydride; inhalation or skin/eye contact may cause severe irritation or burns.
- Reacts with water to release heat and propionic acid; large quantities can react vigorously.
- Vapors are heavier than air and may form explosive mixtures when heated.
- Liquid can fume and irritate eyes, skin and respiratory tract.
- Fire may produce carbon monoxide, acid vapors and other irritating/toxic gases.
- Runoff may be acidic, corrosive and contaminated.
- 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. Fuming liquid at room temperature.
| Also known as | Propanoic anhydrideMethylacetic anhydridePropanoic acid anhydridePropionic acid anhydride |
| CAS Number | 123-62-6 |
| Appearance | Colorless to pale yellow liquid with a pungent, acrid odor. Fuming liquid at room temperature. |
| Flash Point | 63°C (145°F) |
| Boiling Point | 167°C (333°F) |
| Vapor Density | 4.4 (heavier than air) |
| Water Reactivity | Reacts with water liberating heat and propionic acid; violent reaction possible with large quantities |
Fireground Response Guidance — UN 2496
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, dust, mist, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing.
Isolation & Evacuation
First Actions for a UN 2496 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream.
- Avoid breathing vapor, dust, mist, smoke or fumes and avoid skin or eye contact.
- Avoid unnecessary water contact with released product because heat, gas or pressure buildup may occur.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 156, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2496 — Propionic anhydrideUse 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.