UN 2267 — Dimethyl thiophosphoryl chloride
Placard: Toxic. ERG Guide 156. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2267 is Dimethyl thiophosphoryl chloride, a toxic corrosive moisture-sensitive liquid assigned to ERG Guide 156. Water or moist air can release hydrogen chloride and other toxic decomposition products.
Hazard overview: TOXIC and CORROSIVE moisture-sensitive liquid; inhalation, ingestion or skin/eye contact may cause severe injury. Reacts with water or moist air, releasing heat, hydrogen chloride and phosphorus/sulfur-containing decomposition products. Combustible material: may burn but does not ignite readily.
Response guidance: For a UN 2267 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 156. Establish incident command, isolate the area, stay upwind, control ignition or incompatibility hazards, prevent runoff, dust or vapor spread and base entry/fire-control actions on monitoring and local SOP.
Firefighter training notes: Training for UN 2267 should emphasize moisture-reactive toxic/corrosive liquid behavior, HCl fuming, dry-agent selection, Level A/B entry decisions and decontamination. Use ERG 156, SDS and local SOP.
Regulatory context: Dimethyl thiophosphoryl chloride is regulated as a hazardous material for transportation and emergency response purposes. Storage, workplace exposure, emergency planning, spill reporting, waste handling and environmental requirements vary by exact product, concentration, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, container markings and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Dimethyl thiophosphoryl chloride should be stored dry in tightly closed compatible containers away from water, moisture, bases, oxidizers, heat and unauthorized access. Provide secondary containment and plan for corrosive/toxic decontamination waste.
UN 2267 Quick Details
Common Hazards of UN 2267
- TOXIC and CORROSIVE moisture-sensitive liquid; inhalation, ingestion or skin/eye contact may cause severe injury.
- Reacts with water or moist air, releasing heat, hydrogen chloride and phosphorus/sulfur-containing decomposition products.
- Combustible material: may burn but does not ignite readily.
- Vapors are heavier than air and may collect in low or confined areas.
- Fire may produce hydrogen chloride, phosphorus oxides, sulfur oxides and other toxic/corrosive gases.
- Runoff may be acidic, toxic and corrosive.
- Containers may rupture or fail when heated or contaminated with water.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a pungent, irritating odor. Corrosive and moisture-sensitive at room temperature.
| Also known as | Dimethyl chlorothiophosphateO,O-Dimethyl thiophosphoryl chlorideThiophosphoryl chloride dimethyl esterDMTPC |
| CAS Number | 2524-03-0 |
| Appearance | Colorless to pale yellow liquid with a pungent, irritating odor. Corrosive and moisture-sensitive at room temperature. |
| Flash Point | 118C (244F) |
| Boiling Point | 169C (336F) |
| Vapor Density | 5.9 (heavier than air) |
| Water Reactivity | Reacts with water releasing toxic hydrogen chloride gas and corrosive/flammable fumes; avoid water contact |
Fireground Response Guidance — UN 2267
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, aerosol, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing selected from SDS; Level A may be needed for heavy vapor, moisture reaction or unknown concentrations.
Isolation & Evacuation
First Actions for a UN 2267 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, mist, smoke or fumes and avoid skin or eye contact.
- Avoid unnecessary water contact with released product unless incident command confirms a compatible control use.
- Do not touch damaged containers or 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 release area and expand the perimeter for fire involvement, vapor spread, dust generation, water reaction or unknown product identity.
- Use ERG Guide 156, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2267 — Dimethyl thiophosphoryl chlorideUse 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.