UN 2745 — Chloromethyl chloroformate
Placard: Toxic. ERG Guide 157. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2745 is Chloromethyl chloroformate, a toxic corrosive chloroformate assigned to ERG Guide 157. Moisture can release HCl and formaldehyde-type products.
Hazard overview: TOXIC and CORROSIVE chloroformate liquid; inhalation or skin contact may cause severe injury. Reacts with water or moist air to release hydrogen chloride, formaldehyde-type products and heat. Fumes in moist air; vapors are heavier than air and may collect in low or confined areas.
Response guidance: For UN 2745, 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 157.
Firefighter training notes: Training for UN 2745 should emphasize moisture-reactive corrosive fuming, dry-agent choice, SCBA/Level A decisions, decontamination and acidic runoff control. Use ERG 157, SDS and local SOP.
Regulatory context: Chloromethyl chloroformate 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: Chloromethyl chloroformate should be stored dry in tightly closed compatible containers away from water, moisture, bases, alcohols, amines, heat and unauthorized access. Provide secondary containment.
UN 2745 Quick Details
Common Hazards of UN 2745
- TOXIC and CORROSIVE chloroformate liquid; inhalation or skin contact may cause severe injury.
- Reacts with water or moist air to release hydrogen chloride, formaldehyde-type products and heat.
- Fumes in moist air; vapors are heavier than air and may collect in low or confined areas.
- Combustible behavior may vary, but toxic/corrosive exposure is the primary hazard.
- Fire may produce hydrogen chloride, phosgene-type gases and other toxic/corrosive smoke.
- Runoff may be acidic, toxic and corrosive.
- Containers may rupture when heated or contaminated with water.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a pungent, irritating odor. Fumes in moist air due to reaction with atmospheric moisture.
| Also known as | Chloromethyl chlorocarbonateChloroformic acid chloromethyl esterCarbonochloridic acid chloromethyl ester |
| CAS Number | 22128-62-7 |
| Appearance | Colorless to pale yellow liquid with a pungent, irritating odor. Fumes in moist air due to reaction with atmospheric moisture. |
| Flash Point | Not readily available; presents primarily toxic/corrosive hazard |
| Boiling Point | 105-107C (221-225F) |
| Vapor Density | ~4.4 (heavier than air) |
| Water Reactivity | Reacts with water and moist air releasing toxic and corrosive hydrogen chloride (HCl) and formaldehyde gases; reaction generates heat |
Fireground Response Guidance — UN 2745
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 2745 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 157, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2745 — Chloromethyl chloroformateUse 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.