☣️ UN 2743 • CLASS 6
n-Butyl chloroformate
Placard: Toxic. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
🚒☣️
⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
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Quick details
UN 2743
Class: 6
Placard type: Toxic
ERG: Guide 155 (check current ERG)
Isolation: ERG 155: isolate spill or leak area immediately for at least 50 meters in all directions; if tank/rail car involved in fire, isolate 800 meters in all directions
Chemical & Response Details
| Also known as | n-Butyl chlorocarbonateButyl chloroformateChloroformic acid butyl esterFormic acid chloro-, butyl ester |
| CAS Number | 592-34-7 |
| Appearance | Colorless to pale yellow liquid with a pungent, irritating odor. Liquid at room temperature. |
| Flash Point | 29°C (84°F) |
| Boiling Point | 142°C (288°F) |
| Vapor Density | 4.7 (heavier than air) |
| Water Reactivity | Reacts with water releasing toxic and corrosive hydrogen chloride gas; avoid water contact |
| Extinguishing | Dry chemical, CO2, or alcohol-resistant foam; avoid direct water spray on liquid |
| PPE | ⚠️ Level B minimum; SCBA required; full chemical-resistant suit; material is toxic and corrosive |
| Isolation | ERG 155: isolate spill or leak area immediately for at least 50 meters in all directions; if tank/rail car involved in fire, isolate 800 meters in all directions |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames.
- Vapors form explosive mixtures with air: indoors, outdoors and sewers explosion hazards.
- Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas
- Vapors may travel to source of ignition and flash back.
- Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
- Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff.
- Corrosives in contact with metals may evolve flammable hydrogen gas.
- Containers may explode when heated or if contaminated with water.
First actions (field-minded)
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
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UN 2743 — n-Butyl chloroformate HAZMAT RADIO NOTE — UN 2743
Product: n-Butyl chloroformate
Class 6 / Toxic / ERG 155
PPE: Level B minimum; SCBA required; full chemical-resistant suit; material is toxic and corrosive
ISOLATION: ERG 155: isolate spill or leak area immediately for at least 50 meters in all directions; if tank/rail car involved in fire, isolate 800 meters in all directions
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 2743 — n-Butyl chloroformate
Class: 6 | Placard: Toxic | ERG Guide: 155
Appearance: Colorless to pale yellow liquid with a pungent, irritating odor. Liquid at room temperature.
Water Reactivity: Reacts with water releasing toxic and corrosive hydrogen chloride gas; avoid water contact
Extinguishing: Dry chemical, CO2, or alcohol-resistant foam; avoid direct water spray on liquid
PPE: Level B minimum; SCBA required; full chemical-resistant suit; material is toxic and corrosive
Isolation: ERG 155: isolate spill or leak area immediately for at least 50 meters in all directions; if tank/rail car involved in fire, isolate 800 meters in all directions
— Key Hazards —
• HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames.
• Vapors form explosive mixtures with air: indoors, outdoors and sewers explosion hazards.
• Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
SOURCE: allfirefighter.com/hazmat/un/2743 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2743 n-Butyl chloroformate Cls6 ERG155 | ERG 155: isolate spill or leak area immediately for at least 50 meters in all di | allfirefighter.com/hazmat/un/2743SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions. Page: https://allfirefighter.com/hazmat/un/2743
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FAQ
HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors form explosive mixtures with air: indoors, outdoors and sewers explosion hazards. Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas Vapors may travel to source of ignition and flash back. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff. Corrosives in contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water.
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level B minimum; SCBA required; full chemical-resistant suit; material is toxic and corrosive
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 155 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles. This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.