UN/NA Number Reference
DOT Class 6.1 Toxic Substance placard

UN 1670: Perchloromethyl mercaptan

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 1670 is assigned the proper shipping name Perchloromethyl mercaptan 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.

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 157)

Hazards: TOXIC and/or CORROSIVE. Reacts with water. Non-combustible in themselves.

Fire: DO NOT use water. Dry chemical, CO2, dry sand.

Spill: Do not touch. Keep material dry.

Chemical and Physical Properties

Perchloromethyl mercaptan appears as a yellow oily liquid with an offensive odor. Insoluble in water. Density 1.72 g / cm3. Hence sinks in water. Nonflammable but supports combustion. Very toxic by inhalation or skin absorption.

CAS Number: 594-42-3
Molecular Formula: CCl4S
Molecular Weight: 185.9 g/mol
Color / Form: OILY, YELLOW LIQUID
Odor: STRONG UNPLEASANT
Boiling Point: 297 to 298 F
Specific Gravity: 1.6947 (sinks in water)
Vapor Pressure: 25 mmHg at 123.8 F
Vapor Density: 6.414 (heavier than air)
Water Solubility: less than 1 mg/mL at 70 F

Regulatory Data

CERCLA RQ (40 CFR 302.4)
100 lb
EPCRA TPQ (40 CFR 355)
500 lb
OSHA PEL
TWA 0.1 ppm (0.8 mg/m 3 )
NIOSH REL
TWA 0.1 ppm (0.8 mg/m 3 )
IDLH
10 ppm

A release of this material at or above its CERCLA reportable quantity (100 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: 2, B9, B14, B32, N34, T20, TP2, TP13, TP38, TP45. 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 1670 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.