UN 1770 — Diphenylmethyl bromide
Placard: Corrosive. ERG Guide 153. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1770 is Diphenylmethyl bromide, a toxic corrosive organic bromide assigned to ERG Guide 153. It is usually a solid that may create corrosive hydrogen bromide fumes when heated or hydrolyzed.
Hazard overview: UN 1770 presents toxic dust, corrosive contact and HBr-type decomposition hazards. Molten material can burn skin, and runoff may spread toxic/corrosive contamination.
Response guidance: For a UN 1770 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 153. 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 1770 should emphasize corrosive exposure routes, water or oxidizer incompatibility where applicable, air monitoring, PPE selection, decontamination and runoff containment. Use ERG 153, SDS and local SOP.
Regulatory context: Diphenylmethyl bromide is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, pesticide/waste handling where applicable, storage and environmental requirements may vary by formulation, concentration, 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: Diphenylmethyl bromide 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 1770 Quick Details
Common Hazards of UN 1770
- TOXIC and CORROSIVE organic bromide; inhalation, ingestion or skin contact may cause severe injury.
- Dust, vapor or molten material can irritate or burn eyes, skin and respiratory tissue.
- Combustible solid: may burn under fire conditions.
- Hydrolysis or fire may produce corrosive hydrogen bromide and other toxic gases.
- Runoff may carry toxic/corrosive contamination.
- Containers may rupture or fail when heated.
- Avoid dust and molten-material contact.
Chemical Identity & Physical Properties
White to pale yellow crystalline solid with a pungent, irritating odor. May be encountered as a molten liquid at elevated temperatures.
| Also known as | Benzhydryl bromideBromodiphenylmethaneα-BromodiphenylmethaneBenzohydryl bromide |
| CAS Number | 776-74-9 |
| Appearance | White to pale yellow crystalline solid with a pungent, irritating odor. May be encountered as a molten liquid at elevated temperatures. |
| Flash Point | Not applicable (solid at room temperature) |
| Boiling Point | 192C (378F) with decomposition |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Hydrolyzes slowly in water, releasing hydrogen bromide (corrosive vapors) |
Fireground Response Guidance — UN 1770
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, mist, dust, fire or confined-space exposure. Chemical-resistant gloves, boots, eye/face protection and protective clothing should be selected from SDS.
Isolation & Evacuation
First Actions for a UN 1770 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 spray and avoid skin or eye contact.
- 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, dust, fire involvement, water reaction or unknown concentration is present.
- Use ERG Guide 153, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1770 — Diphenylmethyl bromideUse 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.