UN/NA Number Reference
DOT Class 6.1 Toxic Substance placard

UN 1688: Sodium cacodylate

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 1688 is assigned the proper shipping name Sodium cacodylate 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 II. 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 151)

Hazards: TOXIC. May be fatal if inhaled, ingested, or absorbed through skin. Contact may cause burns.

Fire: Use agent appropriate for surrounding fire. Cool containers with water.

Spill: Do not touch. Avoid inhalation. Use water spray to reduce dust/vapor. Ventilate.

Chemical and Physical Properties

Sodium cacodylate appears as a white crystalline or granular solid with a slight odor. Toxic by ingestion, inhalation, and skin absorption. Used as a herbicide.

CAS Number: 124-65-2
Molecular Formula: C2H6AsNaO2
Molecular Weight: 159.98 g/mol
Color / Form: Colorless to light yellow
Odor: None
Melting Point: 140 °F 140 °F for trihydrate. Liquifies in water of hydration at 140 °F and becomes anhydrous at 284 °F (EPA, 1998)
Specific Gravity: greater than 1
Vapor Pressure: 0.00000003 [mmHg]
Water Solubility: Soluble in short chain alcohols

Regulatory Data

EPCRA TPQ (40 CFR 355)
100 lb

Special Provisions

49 CFR 172.102 special provision codes for this entry: IB8, IP2, IP4, T3, TP33. 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 1688 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.