Chemical Datasheet

MERCURY THIOCYANATE

Chemical Identifiers

CAS Number	UN/NA Number	DOT Hazard Label	USCG CHRIS Code
592-85-8	1646	Poison	MRT
NIOSH Pocket Guide		International Chem Safety Card
Mercury compounds [except (organo) alkyls] (as Hg)		none

NFPA 704

data unavailable

General Description

An odorless white crystalline powder. Insoluble in water and denser than water. Hence sinks in water. Very toxic by inhalation and ingestion.

Hazards

Reactivity Alerts

none

Air & Water Reactions

Insoluble in water.

Fire Hazard

Special Hazards of Combustion Products: When heated, decomposes into mercury, nitrogen, etc., at about 165°C.

Behavior in Fire: When heated, swells up to many times its original volume. (USCG, 1999)

Health Hazard

INHALATION: Acute poisoning symptoms are: Tightness in the chest, difficulty in breathing, coughing, and pain in the chest. EYES: Ulceration of conjunctiva and cornea. SKIN: Irritation, sensitization dermatitis. INGESTION: Necrosis, pain, vomiting, severe purging. Patient may die within a few hours from peripheral vascular collapse. (USCG, 1999)

Reactivity Profile

MERCURY THIOCYANATE decomposes into its elements at about 165°C. Burns readily in air to generate a coil of cohesive ash resembling a serpent (hence used in a firework: Pharaoh's serpents). Swells up to many times its original volume if heated (USCG, 1999). Soluble in dilute hydrochloric acid [Merck]. Incompatible with strong oxidizing agents.

Belongs to the Following Reactive Group(s)

Salts, Basic
Reducing Agents, Strong

Potentially Incompatible Absorbents

No information available.

Response Recommendations

Isolation and Evacuation

Excerpt from 151

[Substances - Toxic (Non-Combustible)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.

SPILL: Increase the immediate precautionary measure distance, in the downwind direction, as necessary.

FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2020)

Firefighting

Excerpt from 151

[Substances - Toxic (Non-Combustible)]:

SMALL FIRE: Dry chemical, CO2 or water spray.

LARGE FIRE: Water spray, fog or regular foam. If it can be done safely, move undamaged containers away from the area around the fire. Dike runoff from fire control for later disposal. Avoid aiming straight or solid streams directly onto the product.

FIRE INVOLVING TANKS OR CAR/TRAILER LOADS: Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles. Do not get water inside containers. Cool containers with flooding quantities of water until well after fire is out. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2020)

Non-Fire Response

Excerpt from 151

[Substances - Toxic (Non-Combustible)]:

Do not touch damaged containers or spilled material unless wearing appropriate protective clothing. Stop leak if you can do it without risk. Prevent entry into waterways, sewers, basements or confined areas. Cover with plastic sheet to prevent spreading. Absorb or cover with dry earth, sand or other non-combustible material and transfer to containers. DO NOT GET WATER INSIDE CONTAINERS. (ERG, 2020)

Protective Clothing

Dust mask or self-contained breathing apparatus, when required; rubber gloves, safety or chemical goggles, disposable clothing, or rubber apron. (USCG, 1999)

DuPont Tychem® Suit Fabrics

No information available.

First Aid

Get medical attention.

INHALATION: Remove from exposure.

EYES: Flush with water.

SKIN: Wash thoroughly with water.

INGESTION: Give egg white, milk, or activated charcoal, then induce vomiting. Consult physician. (USCG, 1999)

Physical Properties

Chemical Formula:

C2N2S2.Hg

Flash Point: greater than 250°F (USCG, 1999)

Lower Explosive Limit (LEL): data unavailable

Upper Explosive Limit (UEL): data unavailable

Autoignition Temperature: data unavailable

Melting Point: data unavailable

Vapor Pressure: data unavailable

Vapor Density (Relative to Air): data unavailable

Specific Gravity: 4 Approximately (USCG, 1999) - Denser than water; will sink

Boiling Point: Decomposes about 329.0°F (USCG, 1999)

Molecular Weight: 316.79 (USCG, 1999)

Water Solubility: data unavailable

Ionization Energy/Potential: data unavailable

IDLH: 10 mg Hg/m3 (NIOSH, 2023)

AEGLs (Acute Exposure Guideline Levels)

No AEGL information available.

ERPGs (Emergency Response Planning Guidelines)

No ERPG information available.

PACs (Protective Action Criteria)

Chemical	PAC-1	PAC-2	PAC-3
Mercuric thiocyanate; (Mercuric sulfocyanate) (592-85-8)	0.12 mg/m3	0.16 mg/m3	44 mg/m3

(DOE, 2018)

Regulatory Information

EPA Consolidated List of Lists

Regulatory Name	CAS Number/ 313 Category Code	EPCRA 302 EHS TPQ	EPCRA 304 EHS RQ	CERCLA RQ	EPCRA 313 TRI	RCRA Code	CAA 112(r) RMP TQ
Mercuric thiocyanate	592-85-8			10 pounds	313c
Mercury Compounds	N458			&	313

313c indicates that although not listed by name and CAS number, this chemical is reportable under one or more of the EPCRA section 313 chemical categories.
& indicates that no RQ is assigned to this generic or broad class, although the class is a CERCLA hazardous substance. See 50 Federal Register 13456 (April 4, 1985).

(EPA List of Lists, 2022)

CISA Chemical Facility Anti-Terrorism Standards (CFATS)

No regulatory information available.

OSHA Process Safety Management (PSM) Standard List

No regulatory information available.

Alternate Chemical Names

MERCURIC ISOTHIOCYANATE
MERCURIC SULFOCYANATE
MERCURIC SULFOCYANIDE
MERCURIC THIOCYANATE
MERCURIC THIOCYANATE, [SOLID]
MERCURY DI(THIOCYANATE)
MERCURY RHODANIDE
MERCURY THIOCYANATE
MERCURY THIOCYANATE (HG(SCN)2)
MERCURY(II) THIOCYANATE