UN/NA Number Reference
DOT Class 2.3 Toxic Gas placard

UN 1067: Dinitrogen tetroxide

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 1067 is assigned the proper shipping name Dinitrogen tetroxide in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 2.3 Toxic Gas material. Required label(s): 2.3, 5.1, 8.

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 124)

Hazards: TOXIC. Oxidizer. May accelerate fire. Corrosive. May cause severe burns.

Fire: Use water spray or fog. Do not use dry chemical or CO2. Cool containers.

Spill: Do not touch. Stop leak if safe. Keep combustibles away from spilled material.

Chemical and Physical Properties

Nitrogen tetroxide appears as red-brown liquid with a sharp, unpleasant chemical odor. Low-boiling (boiling point 21.15 °C) and held as a liquid by compression. Density 1.448 g / cm3. Consists of an equilibrium mixture of brown NO2 (nitrogen dioxide) and colorless N2O4 (dinitrogen tetroxide). Evolves poisonous brown vapors. Cylinders and ton containers may not be equipped with a safety relief device. Prolonged exposure of the containers to fire or heat may result in their violent rupturing and rocketing.

CAS Number: 10544-72-6
Molecular Formula: N2O4
Molecular Weight: 92.011 g/mol
Color / Form: Colorless gas
Boiling Point: 70.1 F
Melting Point: 11.8 °F (USCG, 1999)
Autoignition: Not flammable (USCG, 1999)
Specific Gravity: 1.45 (sinks in water)
Vapor Pressure: 1551 mmHg
Water Solubility: Reacts with water

Regulatory Data

CERCLA RQ (40 CFR 302.4)
10 lb

A release of this material at or above its CERCLA reportable quantity (10 lb) requires immediate notification to the National Response Center at 800-424-8802.

Special Provisions

49 CFR 172.102 special provision codes for this entry: 1, B7, B14, B45, B46, B61, B66, B67, B77, T50, TP21. 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 1067 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.