Sodium thiocyanate
[CAS 540-72-7]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Cyanide, cyanide oxide and cyanide complex
• Name: Sodium thiocyanate
• Molecular Formula: NaSCN
• Molecular Weight: 81.06
• CAS Registry Number: 540-72-7
• EC Number: 208-754-4
• SMILES: C(#N)[S-].[Na+]

Properties

• Density: 1.74 g/mL (Expl.)
• Melting point: 287 °C (Expl.)
• Boiling point: 400 °C (Expl.)
• Solubility: Soluble in water: 139 g/100 mL (21 °C), so,uble in acetone, alcohol (Expl.)

Safety Data

• Hazard Symbols: GHS05;GHS07 Danger
• Risk Statements: H302+H312+H332-H302-H312-H318-H319-H332-H412
• Safety Statements: P261-P264-P264+P265-P270-P271-P273-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P305+P354+P338-P317-P321-P330-P337+P317-P362+P364-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	4	H312
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Serious eye damage	Eye Dam.	1	H318
Eye irritation	Eye Irrit.	2	H319
Skin sensitization	Skin Sens.	1	H317
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Acute toxicity	Acute Tox.	3	H311
Acute toxicity	Acute Tox.	3	H331
Specific target organ toxicity - repeated exposure	STOT RE	2	H373

chemBlink Chemical Story

Sodium thiocyanate, CAS 540-72-7, is the sodium salt NaSCN. PubChem records a molecular weight of 81.07 and describes the pure material as an odorless white solid readily mixing with water. The thiocyanate ion, SCN-, is a pseudohalide: although it is not a halide ion, some of its coordination and reaction behavior resembles that of halides.

SCN- is especially interesting because it can interact with metals through either sulfur or nitrogen, depending on the metal and chemical environment. This ambidentate behavior makes thiocyanate useful in coordination and analytical chemistry. The intense red complex formed between iron(III) and thiocyanate is a classic qualitative and spectrophotometric reaction used to illustrate chemical equilibria and metal-ligand complex formation.

Sodium thiocyanate is also an industrial intermediate. Concentrated aqueous solutions are used where a highly soluble thiocyanate source is needed, and thiocyanate chemistry appears in textile, polymer, photographic and chemical-manufacturing contexts. It can serve as a starting material for other thiocyanates and sulfur/nitrogen-containing compounds.

In solution, sodium thiocyanate dissociates into sodium and thiocyanate ions, so many applications depend primarily on SCN-. Thiocyanate is much less acutely toxic than cyanide despite the similarity of their names; SCN- contains sulfur and has very different chemical and biological behavior from CN-.

References:
1. PubChem, Sodium thiocyanate, CID 516871, CAS 540-72-7.
2. Greenwood NN, Earnshaw A. Chemistry of the Elements. 2nd ed. Butterworth-Heinemann, 1997.
3. Skoog DA et al. Fundamentals of Analytical Chemistry. Cengage.

Read more stories