Sodium cyanide
[CAS 143-33-9]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Cyanide, cyanide oxide and cyanide complex
• Name: Sodium cyanide
• Molecular Formula: NaCN
• Molecular Weight: 49.00
• CAS Registry Number: 143-33-9
• EC Number: 205-599-4
• SMILES: [C-]#N.[Na+]

Properties

• Density: 1.6 g/mL (Expl.)
• Melting point: 563.3 - 564.4 °C (Expl.)
• Boiling point: 1495.6 - 1496.7 °C (Expl.)
• Solubility: water: soluble 58.0 g/100g (Expl.)

Safety Data

• Hazard Symbols: GHS05;GHS06;GHS07;GHS08;GHS09 DangerGHS05
• Risk Statements: H290-H300+H310+H330-H300-H310-H315-H318-H319-H330-H372-H400-H410
• Safety Statements: P234-P260-P262-P264-P264+P265-P270-P271-P273-P280-P284-P301+P316-P302+P352-P304+P340-P305+P351+P338-P305+P354+P338-P316-P317-P319-P320-P321-P330-P332+P317-P337+P317-P361+P364-P362+P364-P390-P391-P403+P233-P405-P406-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	1	H310
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Acute toxicity	Acute Tox.	2	H330
Specific target organ toxicity - repeated exposure	STOT RE	1	H372
Acute toxicity	Acute Tox.	2	H300
Acute toxicity	Acute Tox.	1	H300
Acute toxicity	Acute Tox.	1	H330
Serious eye damage	Eye Dam.	1	H318
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	1	H370
Skin corrosion	Skin Corr.	1	H314
Skin corrosion	Skin Corr.	1B	H314
Acute toxicity	Acute Tox.	2	H310

• Transport Information: UN 1689

chemBlink Chemical Story

Sodium cyanide, CAS 143-33-9, is the sodium salt of hydrogen cyanide, with formula NaCN. PubChem records it as a white crystalline material and emphasizes its extreme acute toxicity. Its industrial importance comes mainly from the cyanide ion's exceptionally strong ability to coordinate metals, a property useful in controlled industrial chemistry but also central to the compound's hazards.

The largest well-documented use is precious-metal mining. Government of Canada assessments identify sodium cyanide as an extraction agent used mainly for gold and silver. Cyanide forms soluble complexes with these metals, allowing precious-metal values to be separated from mineral solids in carefully engineered processing systems. Cyanide chemistry has also been used in metal finishing and as an industrial chemical intermediate.

The same small CN- ion that binds metals can interfere with essential biological metal centers. Acute cyanide poisoning disrupts cellular oxygen utilization, which is why sodium cyanide is treated as a highly hazardous industrial chemical. Contact with acids is particularly dangerous because acidification can release hydrogen cyanide gas. Industrial use therefore depends on tightly controlled closed processes, monitoring, trained personnel and regulated waste treatment.

Environmental management is equally important because free cyanide and related species can be toxic to aquatic and terrestrial organisms. Sodium cyanide is a stark example of chemical usefulness and chemical hazard arising from the same molecular property: strong interaction with metal centers enables important industrial separations, while interaction with biological metal-containing enzymes creates severe toxicity.

References:
1. PubChem, Sodium cyanide, CID 8929, CAS 143-33-9.
2. Government of Canada. Risk Management Scope for Cyanides: Metal Mining.
3. International Cyanide Management Institute. International Cyanide Management Code.

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