 | |
 | |
| Names | |
|---|---|
| IUPAC name Thiocyanic acid[4] | |
| Other names | |
| Identifiers | |
| |
3D model (JSmol) |
|
| ChEBI | |
| ChEMBL | |
| ChemSpider |
|
| ECHA InfoCard | 100.006.672 |
| EC Number |
|
| 25178 | |
| KEGG |
|
| MeSH | thiocyanic+acid |
| UNII | |
| |
| |
| Properties | |
| HSCN | |
| Molar mass | 59.09 g·mol−1 |
| Appearance | |
| Odor | Pungent |
| Density | 2.04 g/cm3 |
| Melting point | |
| Miscible | |
| Solubility | Soluble inethanol,diethyl ether |
| logP | 0.429 |
| Vapor pressure | 4.73 mmHg (631 Pa)[7] |
| Acidity (pKa) | 0.926 |
| Basicity (pKb) | 13.071 |
| Hazards | |
| GHS labelling: | |
 | |
| Warning | |
| H302,H312,H332,H412 | |
| P261,P264,P270,P271,P273,P280,P301+P312,P302+P352,P304+P312,P304+P340,P312,P322,P330,P363,P501 | |
| Related compounds | |
Related compounds | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Thiocyanic acid is achemical compound with theformulaHSCN andstructureH−S−C≡N, which exists as atautomer with isothiocyanic acid (H−N=C=S).[8] The isothiocyanic acid tautomer tends to dominate with the compound being about 95% isothiocyanic acid in thevapor phase.[9]
It is a moderatelystrong acid,[10] with apKa of 1.1 at 20 °C and extrapolated to zeroionic strength.[11]
One of the thiocyanic acid tautomers, HSCN, is predicted to have atriple bond betweencarbon andnitrogen. Thiocyanic acid has been observed spectroscopically.[12]
Thesalts andesters of thiocyanic acid are known asthiocyanates. The salts are composed of the thiocyanate ion ([SCN]−) and a suitable cation (e.g.,potassium thiocyanate, KSCN). The esters of thiocyanic acid have the general structureR−S−C≡N, where R stands for anorganyl group.
Isothiocyanic acid, HNCS, is aLewis acid whose free energy, enthalpy and entropy changes for its 1:1 association with a variety of Lewis bases in carbon tetrachloride solution at 25 °C have been reported.[13]< HNCS acceptor properties are discussed in theECW model. The salts are composed of the thiocyanate ion ([SCN]−) and a suitable cation (e.g.,ammonium thiocyanate,[NH4]+[SCN]−). Isothiocyanic acid forms isothiocyanatesR−N=C=S, where R stands for anorganyl group.
Thiocyanuric acid is a stable trimer of thiocyanic acid.
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