UN 2751 — Diethylthiophosphoryl chloride
Placard: Corrosive. ERG Guide 156. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2751 is Diethylthiophosphoryl chloride, a corrosive organophosphorus chloride assigned to ERG Guide 156. Water releases HCl and acidic phosphorus/sulfur products.
Hazard overview: CORROSIVE and TOXIC organophosphorus chloride; vapor or liquid can burn eyes, skin and respiratory tissue. Reacts with water or moist air, releasing hydrogen chloride, heat and acidic phosphorus/sulfur-containing products. Combustible liquid; heated vapors may form ignitable mixtures and collect in low areas.
Response guidance: For UN 2751, isolate the spill, stay upwind and use SCBA with chemical protection. Control moisture contact, use compatible dry agents and contain acidic/toxic runoff under SDS and ERG 156.
Firefighter training notes: Training for UN 2751 should emphasize moisture-reactive corrosive fuming, dry-agent choice, SCBA/Level A decisions, decontamination and acidic runoff control. Use ERG 156, SDS and local SOP.
Regulatory context: Diethylthiophosphoryl chloride 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: Diethylthiophosphoryl chloride should be stored dry in tightly closed compatible containers away from water, moisture, bases, alcohols, amines, heat and unauthorized access. Provide secondary containment.
UN 2751 Quick Details
Common Hazards of UN 2751
- CORROSIVE and TOXIC organophosphorus chloride; vapor or liquid can burn eyes, skin and respiratory tissue.
- Reacts with water or moist air, releasing hydrogen chloride, heat and acidic phosphorus/sulfur-containing products.
- Combustible liquid; heated vapors may form ignitable mixtures and collect in low areas.
- Fire may produce hydrogen chloride, sulfur oxides, phosphorus oxides and other toxic/corrosive gases.
- Runoff may be acidic, corrosive and toxic.
- Containers may rupture when heated or contaminated with water.
- Avoid all skin contact and direct water application to released product.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a pungent, irritating odor. Oily consistency at room temperature.
| Also known as | O,O-Diethyl thiophosphoryl chlorideDiethyl chlorothiophosphateDiethoxythiophosphoryl chlorideDiethyl phosphorochloridothioateDETPC |
| CAS Number | 2524-04-01 |
| Appearance | Colorless to pale yellow liquid with a pungent, irritating odor. Oily consistency at room temperature. |
| Flash Point | 85C (185F) |
| Boiling Point | 92-93C (198-199F) at 18 mmHg |
| Vapor Density | 6.2 (heavier than air) |
| Water Reactivity | Reacts with water releasing toxic hydrogen chloride gas and corrosive/flammable vapors. Do not apply water directly to substance. |
Fireground Response Guidance — UN 2751
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 2751 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.
- Avoid breathing vapor, dust, mist, smoke or fumes and avoid skin or eye contact.
- Keep water or moisture contact controlled because it can release heat and corrosive gases.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Prevent contaminated liquid, dust, runoff and decontamination waste from spreading.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 156, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2751 — Diethylthiophosphoryl 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.