UN 2525 — Ethyl oxalate
Placard: Toxic. ERG Guide 156. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2525 is Ethyl oxalate, a toxic combustible ester assigned to ERG Guide 156. Water may hydrolyze it to acidic/corrosive products.
Hazard overview: TOXIC ester liquid; inhalation, ingestion or skin contact may cause injury. Combustible material: may burn but does not ignite readily. Water or moisture may hydrolyze the ester, producing acidic or corrosive products.
Response guidance: For UN 2525, isolate the area, avoid skin contact and use SCBA where dust, vapor, mist or fire is present. Contain toxic/corrosive runoff and verify product controls with SDS and ERG 156.
Firefighter training notes: Training for UN 2525 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: Ethyl oxalate 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: Ethyl oxalate should be stored in approved compatible containers with ventilation, secondary containment and separation from heat, ignition sources, oxidizers and incompatible materials according to SDS.
UN 2525 Quick Details
Common Hazards of UN 2525
- TOXIC ester liquid; inhalation, ingestion or skin contact may cause injury.
- Combustible material: may burn but does not ignite readily.
- Water or moisture may hydrolyze the ester, producing acidic or corrosive products.
- Vapors may collect in low or confined areas when heated.
- Fire may produce carbon monoxide and irritating/toxic decomposition products.
- Runoff may be toxic, acidic or corrosive depending on hydrolysis products.
- Containers may rupture or fail when heated.
Chemical Identity & Physical Properties
Colorless to pale yellow oily liquid with a mild, fruity ester odor. Liquid at room temperature with relatively low volatility.
| Also known as | Diethyl oxalateOxalic acid diethyl esterEthanedioic acid diethyl esterDEO |
| CAS Number | 95-92-1 |
| Appearance | Colorless to pale yellow oily liquid with a mild, fruity ester odor. Liquid at room temperature with relatively low volatility. |
| Flash Point | 76°C (168°F) |
| Boiling Point | 185-186°C (365-367°F) |
| Vapor Density | 4.1 (heavier than air) |
| Water Reactivity | Reacts slowly with water producing ethanol and oxalic acid; reaction accelerates with heat and moisture |
Fireground Response Guidance — UN 2525
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.
Isolation & Evacuation
First Actions for a UN 2525 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.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Prevent contaminated dust, liquid, runoff and decontamination waste from spreading.
- 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 2525 — Ethyl oxalateUse 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.