UN 2529 — Isobutyric acid
Placard: Flammable. ERG Guide 132. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2529 is Isobutyric acid, a corrosive organic acid assigned to ERG Guide 132. Vapors, liquid contact and acidic runoff require control.
Hazard overview: CORROSIVE organic acid; inhalation, ingestion or skin/eye contact may cause severe burns or injury. Combustible or flammable liquid; heated vapors may form ignitable mixtures with air. Vapors are heavier than air and may collect in low or confined areas.
Response guidance: For UN 2529, 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 132.
Firefighter training notes: Training for UN 2529 should emphasize toxic/corrosive exposure routes, skin absorption, SCBA use, decontamination, runoff containment and SDS verification. Use ERG 132, SDS and local SOP.
Regulatory context: Isobutyric acid 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: Isobutyric acid 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 2529 Quick Details
Common Hazards of UN 2529
- CORROSIVE organic acid; inhalation, ingestion or skin/eye contact may cause severe burns or injury.
- Combustible or flammable liquid; heated vapors may form ignitable mixtures with air.
- Vapors are heavier than air and may collect in low or confined areas.
- Water contact forms acidic solution; dilution can spread corrosive contamination.
- Fire may produce hydrogen chloride where chlorinated, carbon monoxide and irritating/toxic smoke.
- Runoff may be acidic, corrosive and environmentally harmful.
- Containers may rupture or fail when heated.
Chemical Identity & Physical Properties
Colorless liquid with a pungent, rancid butter-like odor. Corrosive organic acid that is miscible with water and most organic solvents.
| Also known as | 2-Methylpropanoic acidIsopropylformic acidDimethylacetic acid2-Methylpropionic acid |
| CAS Number | 79-31-2 |
| Appearance | Colorless liquid with a pungent, rancid butter-like odor. Corrosive organic acid that is miscible with water and most organic solvents. |
| Flash Point | 56°C (132°F) |
| Boiling Point | 154°C (309°F) |
| Vapor Density | 3.0 (heavier than air) |
| Water Reactivity | Miscible with water; no violent reaction but solution is corrosive |
Fireground Response Guidance — UN 2529
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 2529 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.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 132, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2529 — Isobutyric acidUse 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.