UN 2605 — Methoxymethyl isocyanate
Placard: Toxic. ERG Guide 155. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2605 At a Glance
UN 2605 (Methoxymethyl isocyanate) is listed as DOT Class 6 Toxic and is assigned to ERG Guide 155. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
UN 2605 is Methoxymethyl isocyanate, a toxic flammable isocyanate assigned to ERG Guide 155. Respiratory sensitization, vapor flashback and water reaction are key concerns.
Hazard overview: TOXIC and FLAMMABLE isocyanate liquid; inhalation of vapor or aerosol may cause severe respiratory sensitization. Vapors may ignite and form explosive mixtures with air. Reacts with water to release carbon dioxide, heat and polymeric solids; pressure buildup may occur in closed containers.
Response guidance: For UN 2605, isolate the area, eliminate ignition sources where relevant and use SCBA with chemical protection. Control water contact, contain toxic/corrosive runoff and choose agents using SDS and ERG 155.
Firefighter training notes: Training for UN 2605 should emphasize water/moisture reaction, toxic/corrosive vapor control, SCBA use, foam/dry-agent choice, decontamination and runoff containment. Use ERG 155, SDS and local SOP.
Regulatory context: Methoxymethyl isocyanate 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: Methoxymethyl isocyanate should be stored in tightly closed compatible containers in a cool, dry, ventilated area away from water/moisture, amines, alcohols, acids/bases where incompatible and heat.
UN 2605 Quick Details
Common Hazards of UN 2605
- TOXIC and FLAMMABLE isocyanate liquid; inhalation of vapor or aerosol may cause severe respiratory sensitization.
- Vapors may ignite and form explosive mixtures with air.
- Reacts with water to release carbon dioxide, heat and polymeric solids; pressure buildup may occur in closed containers.
- Skin and eye contact may cause irritation, burns or sensitization.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Fire may produce nitrogen oxides, isocyanate vapors and hydrogen cyanide-type toxic gases.
- Runoff may spread toxic isocyanate contamination.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a pungent, acrid odor. Highly reactive organic compound in the isocyanate family.
| Also known as | Methoxymethyl isocyanateMMICIsocyanic acid methoxymethyl esterMethoxymethanyl isocyanate |
| CAS Number | 39815-82-4 |
| Appearance | Colorless to pale yellow liquid with a pungent, acrid odor. Highly reactive organic compound in the isocyanate family. |
| Flash Point | -7C (19F) |
| Boiling Point | 85-90C (185-194F) |
| Vapor Density | 2.5 (heavier than air) |
| Water Reactivity | Reacts with water to release carbon dioxide and heat; avoid contact with moisture |
Fireground Response Guidance — UN 2605
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical-resistant protective clothing. Level A may be needed for heavy vapor, fuming, splash risk or unknown concentrations.
Isolation & Evacuation
First Actions for a UN 2605 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.
- Eliminate ignition sources if this can be done safely.
- Avoid breathing vapor, dust, gas, mist, smoke or fumes and avoid skin or eye contact.
- Keep water or moisture contact controlled when it may increase reaction, fuming or gas generation.
- 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 155, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2605 — Methoxymethyl isocyanateUse 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.