Sodium cyanate

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

Structure
The anion is described by two resonance structures: N\tC\sO- and -N\dC\dO

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

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:
 * 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.

Uses and reactions
The main use of sodium cyanate is for steel hardening.

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.