UN/NA Number Reference
DOT Class 6.1 Toxic Substance placard

UN 1238: Methyl chloroformate

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 1238 is assigned the proper shipping name Methyl chloroformate 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 I. Required label(s): 6.1, 3, 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 155)

Hazards: TOXIC. Corrosive. Flammable or water-reactive. Produces toxic gases on water contact.

Fire: DO NOT use water unless no alternative. Dry chemical, CO2.

Spill: Do not touch. Keep dry. Use water spray with caution.

Chemical and Physical Properties

Methyl chloroformate appears as a colorless liquid with a pungent odor. Flash point 54 °F. Corrosive to metals and tissue. Vapors heavier than air. Very toxic by inhalation. Used to make other chemicals and insecticides.

CAS Number: 79-22-1
Molecular Formula: C2H3ClO2
Molecular Weight: 94.50 g/mol
Color / Form: CLEAR LIQUID
Odor: Unpleasant, acrid
Boiling Point: 160 F
Melting Point: less than -114 °F (USCG, 1999)
Flash Point: 54 F
Autoignition: 940 °F
Specific Gravity: 1.223 (sinks in water)
Vapor Pressure: 159.0 [mmHg]
Vapor Density: 3.26 (heavier than air)
Water Solubility: SOL IN CHLOROFORM, BENZENE, IN ALL PROPORTIONS IN ALCOHOL, ETHER

Regulatory Data

CERCLA RQ (40 CFR 302.4)
1000 lb
EPCRA TPQ (40 CFR 355)
500 lb
RCRA Waste Code(s)
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A release of this material at or above its CERCLA reportable quantity (1000 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, B9, B14, B30, N34, T22, TP2, TP13, TP38, TP44. 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 1238 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.