UN/NA Number Reference
DOT Class 3 Flammable Liquid placard

UN 2363: Ethyl mercaptan

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 2363 is assigned the proper shipping name Ethyl mercaptan in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 3 Flammable Liquid material, Packing Group I. Required label(s): 3.

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 130)

Hazards: Flammable. Toxic vapor. Harmful if inhaled or absorbed. May accumulate in low areas.

Fire: Dry chemical, CO2, foam, water spray. Do not use straight streams.

Spill: Eliminate ignition sources. Stop leak. Absorb with sand/earth. Prevent waterway contamination.

Chemical and Physical Properties

Ethyl mercaptan appears as a clear colorless low-boiling liquid (boiling point 97 °F) with an overpowering, garlic-like/skunk-like odor. Flash point -55 °F. Less dense than water and very slightly soluble in water. Vapors are heavier than air. Vapors may irritate nose and throat. May be toxic if swallowed, by inhalation or by contact. Added to natural gas as an odorant. Used as a stabilizer for adhesives.

CAS Number: 75-08-1
Molecular Formula: C2H6S
Molecular Weight: 62.14 g/mol
Color / Form: Colorless liquid [Note: A gas above 95 degrees F].
Odor: Leek-like odor
Boiling Point: 93.9 F
Melting Point: -234 °F (USCG, 1999)
Flash Point: less than 0 F
Autoignition: 572 °F (USCG, 1999)
Specific Gravity: 0.826 (floats on water)
Vapor Pressure: 442 mmHg
Vapor Density: 2.14 (heavier than air)
Water Solubility: 0.7 %
Log P: 1.5

Regulatory Data

OSHA PEL
C 10 ppm (25 mg/m 3 )
NIOSH REL
C 0.5 ppm (1.3 mg/m 3 ) [15-minute]
IDLH
500 ppm

Special Provisions

49 CFR 172.102 special provision codes for this entry: T11, TP2, TP13. 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 2363 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.