UN 2416 — Trimethyl borate
Placard: Flammable. ERG Guide 129. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2416 is Trimethyl borate, a highly flammable borate ester assigned to ERG Guide 129. It can hydrolyze slowly while vapors create flashback hazards.
Hazard overview: HIGHLY FLAMMABLE borate ester liquid; vapors may ignite and form explosive mixtures with air. Reacts slowly with water to form methanol and boric acid. Vapors are heavier than air and may travel to ignition sources and flash back.
Response guidance: For UN 2416, isolate the area, eliminate ignition sources, keep vapors out of drains and use SCBA in vapor or fire conditions. Cool containers from a protected distance and choose foam, dry chemical or CO2 using SDS and ERG 129.
Firefighter training notes: Training for UN 2416 should emphasize vapor travel, low-area accumulation, sewer flashback, foam selection, ignition control, container cooling and vapor monitoring. Use ERG 129, SDS and local SOP.
Regulatory context: Trimethyl borate 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: Trimethyl borate should be stored in approved flammable-liquid containers with moisture control, ventilation, spill containment and separation from heat, ignition sources, oxidizers and incompatible materials.
UN 2416 Quick Details
Common Hazards of UN 2416
- HIGHLY FLAMMABLE borate ester liquid; vapors may ignite and form explosive mixtures with air.
- Reacts slowly with water to form methanol and boric acid.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Flame may be difficult to see clearly under some conditions.
- Runoff to sewers may create fire or explosion hazards.
- Fire may produce carbon monoxide and irritating boron-containing smoke.
- Containers may rupture or explode when heated.
Chemical Identity & Physical Properties
Colorless liquid with a pungent, alcohol-like odor. Miscible with most organic solvents.
| Also known as | Boric acid trimethyl esterMethyl borateTrimethoxyboraneBoron trimethoxide |
| CAS Number | 121-43-7 |
| Appearance | Colorless liquid with a pungent, alcohol-like odor. Miscible with most organic solvents. |
| Flash Point | -8C (18F) |
| Boiling Point | 68C (154F) |
| Vapor Density | 3.6 (heavier than air) |
| Water Reactivity | Reacts slowly with water producing methanol and boric acid; avoid prolonged contact |
Fireground Response Guidance — UN 2416
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fire or confined-space exposure. Wear chemical-resistant gloves, eye/face protection and flame-resistant protection as appropriate.
Isolation & Evacuation
First Actions for a UN 2416 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.
- 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 129, SDS, shipping papers and air monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2416 — Trimethyl borateUse 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.