UN/NA Number Reference
DOT Class 6.1 Toxic Substance placard

UN 2504: Tetrabromoethane

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 2504 is assigned the proper shipping name Tetrabromoethane in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 6.1 Toxic Substance material, Packing Group III. Required label(s): 6.1.

Packing group indicates the degree of danger within a hazard class: PG I is high danger, PG II medium, PG III low. The proper shipping name, hazard class, UN number, and packing group together form the basic shipping description that must appear on shipping papers and, where required, on the package and placard.

Emergency Response (ERG Guide 160)

Hazards: Non-flammable in most cases. Toxic by inhalation. Vapors heavier than air. Decomposes in fire producing toxic gases including phosgene.

Fire: Use water spray, dry chemical, CO2, foam.

Spill: Ventilate area. Absorb with earth/sand. Prevent runoff to waterways.

Chemical and Physical Properties

Acetylene tetrabromide appears as a yellowish liquid with a pungent odor, much like camphor. Irritates skin. Ingestion or inhalation may produce irritation or a narcotic effect. Chronic exposure may damage liver. Noncombustible, but decomposes at 374 °F, releasing flammable and toxic fumes. Much denser than water. Used as a solvent for fats, oils and waxes.

CAS Number: 79-27-6
Molecular Formula: C2H2Br4
Molecular Weight: 345.65 g/mol
Color / Form: Yellowish, heavy liquid /SRP: technical grade/
Odor: Odor of camphor and iodoform
Boiling Point: 471 °F at 760 mmHg (NTP, 1992)
Melting Point: 30 °F (NTP, 1992)
Flash Point: 635 °F (NFPA, 2010)
Autoignition: 635 °F (NTP, 1992)
Specific Gravity: 2.9656 at 68 °F (NTP, 1992) - Denser than water; will sink
Vapor Pressure: 0.1 mmHg at 68 °F ; 1 mmHg at 149 °F (NTP, 1992)
Vapor Density: 11.9 (NTP, 1992) - Heavier than air; will sink (Relative to Air)
Water Solubility: less than 1 mg/mL at 68 °F (NTP, 1992)
Log P: 2.8

Regulatory Data

OSHA PEL
TWA 1 ppm (14 mg/m 3 )
NIOSH REL
See Appendix D
IDLH
8 ppm

Special Provisions

49 CFR 172.102 special provision codes for this entry: IB3, T4, TP1. These codes modify the general requirements (packaging, quantity limits, exceptions) for this specific material. Look up each code in 49 CFR 172.102 for the full text.

Need the full interactive record? Open UN 2504 in the SpillNerd lookup tool for the live database entry with placard graphics, GHS pictograms, full segregation tables, and synonym search. For another material, use the UN number and chemical lookup.

Reference data compiled from the DOT Hazardous Materials Table (49 CFR 172.101), the 2024 Emergency Response Guidebook, and public chemical databases (PubChem, NIOSH, EPA). Always verify the correct shipping description against the current regulation and the manufacturer's SDS Section 14 before shipping.