UN 2496 — Propionic anhydride
Placard: Corrosive. ERG Guide 156. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2496 At a Glance
UN 2496 (Propionic anhydride) is listed as DOT Class 8 Corrosive and is assigned to ERG Guide 156. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
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.