UN 1738 — Benzyl chloride
Placard: Toxic. ERG Guide 156. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1738 is Benzyl chloride, a toxic combustible liquid assigned to ERG Guide 156. It can irritate or injure responders by vapor and skin contact and may produce HCl fumes when heated or hydrolyzed.
Hazard overview: UN 1738 presents toxic vapor, combustible liquid, corrosive decomposition and contaminated-runoff hazards. Vapors are heavier than air and may collect in low areas.
Response guidance: For a UN 1738 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 156. Establish incident command, isolate the area, stay upwind, prevent incompatible contact, control runoff and choose entry or fire-control actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1738 should emphasize toxic/corrosive exposure routes, water or oxidizer incompatibility where applicable, air monitoring, PPE selection, decontamination and runoff containment. Use ERG 156, SDS and local SOP.
Regulatory context: Benzyl chloride is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by concentration, formulation, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Benzyl chloride should be stored in tightly closed compatible containers in a secure, cool, dry, well-ventilated hazardous-material area according to SDS and local procedures.
UN 1738 Quick Details
Common Hazards of UN 1738
- TOXIC combustible liquid; inhalation, ingestion or skin contact may cause severe injury.
- Vapors can irritate eyes and respiratory tissue and may be heavier than air.
- Combustible material: may burn but does not ignite readily.
- Hydrolysis with moisture may produce acidic/corrosive hydrogen chloride contamination.
- Heating or fire may produce hydrogen chloride and other toxic/corrosive gases.
- Runoff may carry toxic and corrosive contamination to drains or waterways.
- Containers may rupture or fail when heated.
Chemical Identity & Physical Properties
Colorless to slightly yellow liquid with a pungent, irritating odor. Fumes in moist air. Denser than water.
| Also known as | alpha-ChlorotolueneChloromethylbenzeneBenzyl chlorideChlorophenylmethane |
| CAS Number | 100-44-7 |
| Appearance | Colorless to slightly yellow liquid with a pungent, irritating odor. Fumes in moist air. Denser than water. |
| Flash Point | 67°C (153°F) |
| Boiling Point | 179°C (354°F) |
| Vapor Density | 4.4 (heavier than air) |
| Water Reactivity | Reacts slowly with water releasing HCl (hydrochloric acid) vapors; reaction accelerates with heat |
Fireground Response Guidance — UN 1738
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, mist, fire or confined-space exposure. Chemical-resistant gloves, eye/face protection and protective clothing should be selected from SDS to prevent skin and eye contact.
Isolation & Evacuation
First Actions for a UN 1738 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, fumes, dust, mist or gas and avoid skin or eye contact.
- Eliminate ignition sources if safe and keep vapors out of drains, sewers and low areas.
- Do not touch or walk through 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 leak area and expand the perimeter if vapor, gas, dust, fire involvement, water reaction or unknown concentration is present.
- Use ERG Guide 156, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1738 — Benzyl 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.