UN 1541 — Acetone cyanohydrin, stabilized
Placard: Toxic. ERG Guide 156. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1541 is Acetone cyanohydrin, stabilized, a highly toxic cyanohydrin liquid assigned to ERG Guide 156. Water, heat, alkaline contamination or loss of stabilizer can release hydrogen cyanide, making vapor monitoring and exposure control critical.
Hazard overview: UN 1541 presents hydrogen cyanide release, toxic vapor, combustible liquid and contaminated-runoff hazards. Vapors can collect in low areas, and fire or decomposition may produce cyanide and nitrogen oxide gases.
Response guidance: For a UN 1541 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 and choose extinguishing or spill-control actions based on ERG, SDS and local SOP.
Firefighter training notes: Training for UN 1541 should emphasize hydrogen cyanide release, stabilization loss, water/alkali incompatibility, vapor monitoring, decontamination and early hazmat/medical coordination. Use ERG 156, SDS and local SOP.
Regulatory context: Acetone cyanohydrin, stabilized is regulated as a toxic hazardous material. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by concentration, 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: Acetone cyanohydrin, stabilized should be stored in compatible, secured containers with stabilizer controls maintained, away from heat, alkalis, water contamination and incompatible materials. Storage should include ventilation, cyanide emergency planning and leak control appropriate to the SDS.
UN 1541 Quick Details
Common Hazards of UN 1541
- HIGHLY TOXIC; may release hydrogen cyanide if heated, decomposing, alkaline-contaminated or in contact with water.
- Combustible liquid; vapors may form flammable mixtures when heated.
- Vapors are heavier than air and may collect in low or confined areas.
- Stabilization may be lost if contaminated, heated or exposed to incompatible conditions.
- Fire may produce hydrogen cyanide, nitrogen oxides and other toxic gases.
- Containers may rupture or explode when heated.
- Runoff and contaminated water may carry cyanide hazards.
Chemical Identity & Physical Properties
Colorless to straw-colored liquid with a faint almond-like odor. Liquid at room temperature, typically stabilized with phosphoric acid to prevent decomposition.
| Also known as | 2-Hydroxy-2-methylpropanenitrile2-MethyllactonitrileACHCyanhydrin acetone2-Cyanopropan-2-ol |
| CAS Number | 75-86-5 |
| Appearance | Colorless to straw-colored liquid with a faint almond-like odor. Liquid at room temperature, typically stabilized with phosphoric acid to prevent decomposition. |
| Flash Point | 74°C (165°F) |
| Boiling Point | 95°C (203°F) - decomposes at higher temperatures |
| Vapor Density | 2.9 (heavier than air) |
| Water Reactivity | Reacts with water releasing hydrogen cyanide gas (HCN), a highly toxic flammable gas. Reaction accelerates with heat or alkaline conditions. |
Fireground Response Guidance — UN 1541
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical protective clothing selected by hazmat specialists for any potential vapor or liquid exposure. Level A may be needed for close entry or unknown concentrations because hydrogen cyanide release and skin absorption are major concerns.
Isolation & Evacuation
First Actions for a UN 1541 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, dust or mist and avoid all skin or eye contact.
- 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 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 1541 — Acetone cyanohydrin, stabilizedUse 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.