UN 1723 — Allyl iodide
Placard: Flammable. ERG Guide 132. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1723 is Allyl iodide, a flammable halogenated liquid assigned to ERG Guide 132. Vapors can flash back and may produce toxic iodine-containing decomposition products in fire.
Hazard overview: UN 1723 presents flammable vapor, heavy vapor, flashback and toxic decomposition hazards. Keep vapors out of sewers and low areas and control ignition sources.
Response guidance: For a UN 1723 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 132. 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 1723 should emphasize corrosive/toxic exposure routes, air monitoring, PPE selection, decontamination, runoff containment and compatible extinguishing decisions. Use ERG 132, SDS and local SOP.
Regulatory context: Allyl 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 concentration, formulation, 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: Allyl iodide should be stored in tightly closed compatible containers in a secure, cool, dry, well-ventilated hazardous-material area according to SDS and local procedures.
UN 1723 Quick Details
Common Hazards of UN 1723
- FLAMMABLE liquid; vapors may ignite and form explosive mixtures with air.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Liquid and vapor may irritate eyes, skin and respiratory tissue.
- Heating or fire may produce iodine-containing and other toxic/corrosive gases.
- Runoff to sewers may create fire or explosion hazards.
- Containers may rupture or explode when heated.
- Material may darken or decompose with air, light or heat.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a pungent, acrid odor. Darkens on exposure to light and air. Denser than water.
| Also known as | 3-Iodopropene3-Iodo-1-propeneIodoallylAllyl monoiodide1-Propene, 3-iodo- |
| CAS Number | 556-56-9 |
| Appearance | Colorless to pale yellow liquid with a pungent, acrid odor. Darkens on exposure to light and air. Denser than water. |
| Flash Point | -3C (27F) |
| Boiling Point | 103C (217F) |
| Vapor Density | 5.8 (heavier than air) |
| Water Reactivity | Slightly soluble in water with no significant reaction; hydrolyzes slowly |
Fireground Response Guidance — UN 1723
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fire or confined-space exposure. Chemical-resistant gloves, eye/face protection and protective clothing should be selected from SDS; control ignition and skin contact hazards.
Isolation & Evacuation
First Actions for a UN 1723 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 or mist and avoid skin or eye contact.
- Eliminate ignition sources if it is safe to do so and keep vapors out of drains, sewers and low areas.
- 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 132, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1723 — Allyl 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.