UN 2353 — Butyryl chloride
Placard: Flammable. ERG Guide 155. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2353 is Butyryl chloride, a flammable corrosive acid chloride assigned to ERG Guide 155. Moisture can release hydrogen chloride fumes and acidic runoff.
Hazard overview: FLAMMABLE and CORROSIVE acid chloride liquid; vapors may ignite and cause severe irritation or burns. Reacts with water or moist air to release hydrogen chloride fumes and heat. Vapors are heavier than air and may travel to ignition sources and flash back.
Response guidance: For UN 2353, isolate the release, remove ignition sources, stay upwind and use SCBA. Control water use because moisture can increase corrosive fuming; contain runoff and verify tactics with ERG 155, SDS and incident command.
Firefighter training notes: Training for UN 2353 should emphasize acid chloride moisture reaction, HCl fuming, flammable vapor control, acid-resistant PPE, runoff containment and decontamination. Use ERG 155, SDS and local SOP.
Regulatory context: Butyryl 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: Butyryl chloride should be stored in tightly closed compatible containers in a cool, dry, ventilated flammable/corrosive area away from moisture, heat, ignition sources, oxidizers and bases. Provide secondary containment.
UN 2353 Quick Details
Common Hazards of UN 2353
- FLAMMABLE and CORROSIVE acid chloride liquid; vapors may ignite and cause severe irritation or burns.
- Reacts with water or moist air to release hydrogen chloride fumes and heat.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Liquid contact can burn eyes, skin and respiratory tissue.
- Fire may produce hydrogen chloride, carbon monoxide and other toxic/corrosive gases.
- Runoff may be acidic, corrosive and flammable-contaminated.
- Containers may rupture or explode when heated or contaminated with water.
Chemical Identity & Physical Properties
Clear to pale yellow liquid with a pungent, acrid odor. Fumes in moist air due to reaction with atmospheric moisture.
| Also known as | Butanoyl chlorideButyric acid chloriden-Butyryl chlorideButanoic acid chloride |
| CAS Number | 141-75-3 |
| Appearance | Clear to pale yellow liquid with a pungent, acrid odor. Fumes in moist air due to reaction with atmospheric moisture. |
| Flash Point | 21°C (70°F) |
| Boiling Point | 101-102°C (214-216°F) |
| Vapor Density | 3.7 (heavier than air) |
| Water Reactivity | Reacts violently with water, producing hydrochloric acid fumes and heat. Do not use water directly on material. |
Fireground Response Guidance — UN 2353
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and acid-resistant chemical protective clothing for vapor, fire or spill entry. Level A may be needed for heavy fuming or unknown concentrations.
Isolation & Evacuation
First Actions for a UN 2353 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; keep responders out of low vapor areas.
- Eliminate ignition sources if this can be done safely.
- Avoid breathing vapor, mist or smoke and avoid skin or eye contact.
- Keep water contact limited and controlled because moisture can increase corrosive fuming.
- 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 air monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2353 — Butyryl 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.