UN 2434 — Dibenzyldichlorosilane
Placard: Corrosive. ERG Guide 156. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2434 is Dibenzyldichlorosilane, a corrosive moisture-reactive chlorosilane assigned to ERG Guide 156. Water or moist air releases HCl fumes and heat.
Hazard overview: CORROSIVE moisture-reactive chlorosilane; liquid or vapor contact can cause severe burns. Reacts with water or moist air, releasing hydrogen chloride fumes and heat. Combustible material: may burn but does not ignite readily.
Response guidance: For UN 2434, isolate the spill, stay upwind and use SCBA with chemical protection. Control moisture contact, contain acidic runoff and use dry compatible agents under SDS and ERG 156 guidance.
Firefighter training notes: Training for UN 2434 should emphasize water-reactive corrosive fuming, HCl hazards, dry-agent selection, Level A/B decisions, decontamination and acidic runoff control. Use ERG 156, SDS and local SOP.
Regulatory context: Dibenzyldichlorosilane 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: Dibenzyldichlorosilane should be stored dry in tightly closed compatible containers away from water, moisture, bases, oxidizers/reducing agents where incompatible, heat and unauthorized access. Provide secondary containment.
UN 2434 Quick Details
Common Hazards of UN 2434
- CORROSIVE moisture-reactive chlorosilane; liquid or vapor contact can cause severe burns.
- Reacts with water or moist air, releasing hydrogen chloride fumes and heat.
- Combustible material: may burn but does not ignite readily.
- Vapors are heavier than air and may collect in low or confined areas.
- Fire may produce hydrogen chloride, silicon oxides and other toxic/corrosive gases.
- Runoff may be acidic, corrosive and contaminated with hydrolysis products.
- Containers may rupture when heated or contaminated with water.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a pungent, acrid odor characteristic of chlorosilanes. Denser than water and reacts with it.
| Also known as | DibenzyldichlorosilaneDibenzylsilicon dichlorideBis(phenylmethyl)dichlorosilaneDichloro(dibenzyl)silane |
| CAS Number | 28109-04-8 |
| Appearance | Colorless to pale yellow liquid with a pungent, acrid odor characteristic of chlorosilanes. Denser than water and reacts with it. |
| Flash Point | 105°C (221°F) |
| Boiling Point | 165°C (329°F) at 15 mmHg |
| Vapor Density | Approximately 8.9 (much heavier than air) |
| Water Reactivity | Reacts vigorously with water, releasing hydrogen chloride (HCl) gas which is toxic and corrosive. Avoid direct water contact. |
Fireground Response Guidance — UN 2434
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 2434 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 contact controlled because moisture can increase heat release, corrosive fuming or ignition.
- 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 156, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2434 — DibenzyldichlorosilaneUse 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.