UN/NA Number Reference
DOT Class 2.1 Flammable Gas placard

UN 1012: Butylene

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 1012 is assigned the proper shipping name Butylene in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 2.1 Flammable Gas material. Required label(s): 2.1.

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 115)

Hazards: Extremely flammable. May be ignited by heat, sparks, or flames. Vapors may travel to ignition source and flash back. Containers may rocket or BLEVE.

Fire: Do not extinguish unless flow can be stopped. Use water spray to cool containers. Move containers from fire if safe.

Spill: Eliminate ignition sources. Stop leak if safe. Use water spray to reduce vapors.

Chemical and Physical Properties

1-butene is a colorless gas. (NTP, 1992)

CAS Number: 106-98-9
Molecular Formula: C4H8
Molecular Weight: 112.21 g/mol
Color / Form: Colorless gas
Odor: Slightly aromatic odor
Boiling Point: -6.3 C /1-butene/
Melting Point: -301.5 °F (NTP, 1992)
Flash Point: -110 °F (NTP, 1992)
Autoignition: 723 °F (NTP, 1992)
Specific Gravity: 0.6255 at 19.9 °F (NTP, 1992) - Less dense than water; will float
Vapor Pressure: 3480 mmHg at 70 °F (NTP, 1992)
Vapor Density: 1.93 (NTP, 1992) - Heavier than air; will sink (Relative to Air)
Water Solubility: In water, 222-263 mg/L at 25 C /derived from constituent components of butene, But-1-ene (106-98-9) and 2-methylpropene
Log P: log Kow = 2.40

Special Provisions

49 CFR 172.102 special provision codes for this entry: 19, 398, T50. 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.

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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.