Thiocyanuric acid

Thiocyanuric acid
Identifiers
CAS Number	638-16-4;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL3306346;
ChemSpider	1064800;
ECHA InfoCard	100.010.294
EC Number	211-322-8;
PubChem CID	1268121;
UNII	KX0WZE0QAQ;
CompTox Dashboard (EPA)	DTXSID3045067 ;
	InChI InChI=1S/C3H3N3S3/c7-1-4-2(8)6-3(9)5-1/h(H3,4,5,6,7,8,9) Key: WZRRRFSJFQTGGB-UHFFFAOYSA-N;
	SMILES C1(=S)NC(=S)NC(=S)N1;
Properties
Chemical formula	C3H3N3S3
Molar mass	177.26 g·mol−1
Appearance	yellow solid
Density	135 g/cm3
Melting point	290 °C (554 °F; 563 K)
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302
Precautionary statements	P261, P264, P264+P265, P270, P271, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P319, P321, P330, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Thiocyanuric acid is the organosulfur compound with the formula (HNC=S)₃. It is analogous to cyanuric acid ((HNC=O)₃). Cyanuric acid is white whereas thiocyanuric acid is yellow. It can also be viewed as a trimeric thioamide.

Structure

It is a planar molecular as determined by X-ray crystallography. Like cyanuric acid, thiocyanuric acid forms extended hydrogen-bonded network resulting in a sheet-like structure. This arrangement is relevant to the high melting point of the compound.^[2]

Synthesis, reactions, applications

Thiocyanuric acid precipitates from warm, acidic solutions of thiocyanic acid. A modern synthesis begins instead with a preformed ring: cyanuric chloride reacts with sodium hydrosulfide to give table salt and thiocyanuric acid.^[3]

The compound is mildly acidic, with pKa's of 5.7, 8.4, and 11.4.^[3] Various salts of (HNC=S)−3 have been characterized.^[4]

The compound has an affinity for heavy metals. This attribute has been exploited by applying thiocyanuric acid and derivatives to treatment of waste waters.^[5]

References

^ "Trithiocyanuric acid". pubchem.ncbi.nlm.nih.gov.
^ Brito, Iván; Albanez, Joselyn; Bolte, Michael (2010). "Trithiacyanuric acid: A second triclinic polymorph". Acta Crystallographica Section E: Structure Reports Online. 66 (9): o2382–o2383. Bibcode:2010AcCrE..66o2382B. doi:10.1107/S1600536810033234. PMC 3007918. PMID 21588719.
^ ^a ^b Henke, Kevin R.; Hutchison, Aaron R.; Krepps, Matthew K.; Parkin, Sean; Atwood, David A. (2001). "Chemistry of 2,4,6-Trimercapto-1,3,5-triazine (TMT): Acid Dissociation Constants and Group 2 Complexes". Inorganic Chemistry. 40 (17): 4443–4447. doi:10.1021/ic0103188. PMID 11487353.
^ Dean, Philip A. W.; Jennings, Michael; Houle, Teena M.; Craig, Donald C.; Dance, Ian G.; Hook, James M.; Scudder, Marcia L. (2004). "Crystal packing in tetraphenylphosphonium salts of trithiocyanuric acid and its methanol solvate". CrystEngComm. 6 (88): 543. doi:10.1039/b413145b.
^ Pohl, Alina (2020). "Removal of Heavy Metal Ions from Water and Wastewaters by Sulfur-Containing Precipitation Agents". Water, Air, & Soil Pollution. 231 (10): 503. Bibcode:2020WASP..231..503P. doi:10.1007/s11270-020-04863-w.

[1] "Trithiocyanuric acid". pubchem.ncbi.nlm.nih.gov.

[XRD-2] Brito, Iván; Albanez, Joselyn; Bolte, Michael (2010). "Trithiacyanuric acid: A second triclinic polymorph". Acta Crystallographica Section E: Structure Reports Online. 66 (9): o2382–o2383. Bibcode:2010AcCrE..66o2382B. doi:10.1107/S1600536810033234. PMC 3007918. PMID 21588719.

[Atw-3] Henke, Kevin R.; Hutchison, Aaron R.; Krepps, Matthew K.; Parkin, Sean; Atwood, David A. (2001). "Chemistry of 2,4,6-Trimercapto-1,3,5-triazine (TMT): Acid Dissociation Constants and Group 2 Complexes". Inorganic Chemistry. 40 (17): 4443–4447. doi:10.1021/ic0103188. PMID 11487353.

[4] Dean, Philip A. W.; Jennings, Michael; Houle, Teena M.; Craig, Donald C.; Dance, Ian G.; Hook, James M.; Scudder, Marcia L. (2004). "Crystal packing in tetraphenylphosphonium salts of trithiocyanuric acid and its methanol solvate". CrystEngComm. 6 (88): 543. doi:10.1039/b413145b.

[5] Pohl, Alina (2020). "Removal of Heavy Metal Ions from Water and Wastewaters by Sulfur-Containing Precipitation Agents". Water, Air, & Soil Pollution. 231 (10): 503. Bibcode:2020WASP..231..503P. doi:10.1007/s11270-020-04863-w.

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