UN 1898 — Acetyl iodide
Placard: Corrosive. ERG Guide 156. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1898 is Acetyl iodide, a corrosive water-reactive acid halide assigned to ERG Guide 156. Moisture can release hydrogen iodide and acetic acid fumes with heat.
Hazard overview: UN 1898 presents corrosive vapor, water-reaction, combustible liquid and acidic halide runoff hazards. Do not apply water directly to the material unless specialist guidance confirms a safe use.
Response guidance: For a UN 1898 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, control runoff and choose entry or fire-control actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1898 should emphasize water-reactive fuming behavior, heavy vapor movement, dry-agent selection, runoff control, PPE selection and decontamination. Use ERG 156, SDS and local SOP.
Regulatory context: Acetyl iodide is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by formulation, 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: Acetyl iodide should be stored in tightly closed compatible containers in a cool, dry, well-ventilated area away from water, moisture, bases, oxidizers/reducing agents where incompatible, heat and unauthorized access. Protect containers from corrosion, leakage and contamination.
UN 1898 Quick Details
Common Hazards of UN 1898
- TOXIC and CORROSIVE acid halide liquid; inhalation, ingestion or skin/eye contact may cause severe injury.
- Reacts violently with water or moist air, releasing heat, hydrogen iodide and acetic acid fumes.
- Vapors are heavier than air and may collect in low or confined areas.
- Combustible liquid: may burn under fire conditions.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff may spread acidic iodine/halide contamination.
- 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. Fumes in moist air due to reaction with water vapor.
| Also known as | Acetic acid iodideEthanoyl iodideIodoacetylAcetyl monoiodide |
| CAS Number | 507-02-8 |
| Appearance | Colorless to pale yellow liquid with a pungent, acrid odor. Fumes in moist air due to reaction with water vapor. |
| Flash Point | Not readily flammable but combustible; decomposes on heating |
| Boiling Point | 105-108C (221-226F) |
| Vapor Density | 6.5 (heavier than air) |
| Water Reactivity | Reacts violently with water, releasing hydrogen iodide (corrosive, toxic gas) and acetic acid. Do not use water directly on material. |
Fireground Response Guidance — UN 1898
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fume, dust, fire or confined-space exposure. Chemical-resistant gloves, boots, eye/face protection and protective clothing should be selected from SDS; Level A may be needed for close entry or unknown concentrations.
Isolation & Evacuation
First Actions for a UN 1898 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, fumes, dust, mist or spray and avoid skin or eye contact.
- Keep water and moisture away from released product unless incident command confirms a compatible cooling or control use.
- 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, water reaction 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 1898 — Acetyl iodideUse 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.