Sodium cyanate

Sodium cyanate is the inorganic compound with the formula NaOCN. A white solid, it is the sodium salt of the cyanate anion.

Sodium cyanate

Identifiers
CAS Number	917-61-3 Y
3D model (JSmol)	Interactive image
Beilstein Reference	3655041
ChEBI	CHEBI:38906
ChEMBL	ChEMBL1644696
ChemSpider	12922
ECHA InfoCard	100.011.846
EC Number	213-030-6
MeSH	C009281
PubChem CID	517096
UNII	8UFS3JRV8P Y
CompTox Dashboard (EPA)	DTXSID2061274
InChI InChI=1S/CHNO.Na/c2-1-3;/h3H;/q;+1/p-1 Key: ZVCDLGYNFYZZOK-UHFFFAOYSA-M
SMILES C(#N)[O-].[Na+]
Properties
Chemical formula	NaOCN
Molar mass	65.01 g/mol
Appearance	white crystalline solid
Odor	odorless
Density	1.893 g/cm3
Melting point	550 °C (1,022 °F; 823 K)
Solubility in water	11.6 g/100 mL (25 °C)
Solubility	ethanol: 0.22 g/100 mL (0 °C) dimethylformamide: 0.05 g/100 mL (25 °C) slightly soluble in ammonia, benzene insoluble in diethyl ether
Structure
Crystal structure	body centered rhombohedral
Thermochemistry
Heat capacity (C)	86.6 J/mol K
Std molar entropy (S⦵298)	119.2 J/mol K
Std enthalpy of formation (ΔfH⦵298)	−400 kJ/mol
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H412
Precautionary statements	P264, P270, P273, P301+P312, P330, P501
Lethal dose or concentration (LD, LC):
LD50 (median dose)	1500 mg/kg (rat, oral)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Structure

The anion is described by two resonance structures: N≡C−O⁻ and ⁻N=C=O

The salt adopts a body centered rhombohedral crystal lattice structure (trigonal crystal system) at room temperature.^[1]

Preparation

Sodium cyanate is prepared industrially by the reaction of urea with sodium carbonate at elevated temperature.

2OC(NH₂)₂ + Na₂CO₃ → 2Na(NCO) + CO₂ + 2NH₃ + H₂O

Sodium allophanate is observed as an intermediate:^[2]

H₂NC(O)NHCO₂Na → NaOCN + NH₃ + CO₂

It can also be prepared in the laboratory by oxidation of a cyanide in aqueous solution by a mild oxidizing agent such as lead oxide.^[3]

Uses and reactions

The main use of sodium cyanate is for steel hardening.^[2]

Sodium cyanate is used to produce cyanic acid, often in situ:

NaOCN + HCl → HOCN + NaCl

This approach is exploited for condensation with amines to give unsymmetrical ureas:

HOCN + RNH₂ → RNHC(O)NH₂

Such urea derivatives have a range of biological activity.^[4]

See also

• Cyanate