Prussous acid

Thiocyanic acid

Names
IUPAC name Nitridosulfanidocarbon
Other names Hydrogen thiocyanate Sulfocyanic acid Sulfocyanide
Identifiers
CAS Number	463-56-9 Y
3D model (JSmol)	Interactive image
3DMet	B00344
ChEBI	CHEBI:29200 Y
ChemSpider	760 Y
ECHA InfoCard	100.006.672
EC Number	207-337-4
Gmelin Reference	25178
KEGG	C01755 N
MeSH	thiocyanic+acid
PubChem CID	781
InChI InChI=1S/CHNS/c2-1-3/h3H Y Key: ZMZDMBWJUHKJPS-UHFFFAOYSA-N Y
SMILES SC#N
Properties
Chemical formula	CHNS
Molar mass	59.09 g·mol−1
Appearance	colorless, oily liquid
Odor	pungent
Density	2.04 g/cm3
Melting point	5 °C (41 °F; 278 K)
Solubility in water	Miscible
Solubility	soluble in ethanol, diethyl ether
log P	0.429
Acidity (pKa)	0.926
Basicity (pKb)	13.071
Hazards
EU classification (DSD) (outdated)	Xn
R-phrases (outdated)	R20/21/22, R32, R52/53
S-phrases (outdated)	(S2), S13
Related compounds
Related alkanenitriles	Hydrogen cyanide Cyanogen iodide Cyanogen bromide Cyanogen chloride Cyanogen fluoride Acetonitrile Aminoacetonitrile Glycolonitrile Cyanogen
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Thiocyanic acid is a chemical compound with the formula HSCN which exists as a tautomer with isothiocyanic acid (HNCS). The iso- form tends to dominate with the material being about 95% isothiocyanic acid in the vapor phase.

It is a weak acid, bordering on strong, with a pK_a of 1.1 at 20 °C and extrapolated to zero ionic strength.

HSCN is predicted to have a triple bond between carbon and nitrogen. It has been observed spectroscopically but has not been isolated as a pure substance.

The salts and esters of thiocyanic acid are known as thiocyanates. The salts are composed of the thiocyanate ion (⁻SCN) and a suitable metal cation (e.g., potassium thiocyanate, KSCN). The esters of thiocyanic acid have the general structure R–SCN.