2-Thiouracil

2-Thiouracil is a chemical derivative of uracil in which the oxygen atom in the 2-position of the ring is substituted by sulfur. It is classified as a thiourea.^[1]

2-Thiouracil

Names
Preferred IUPAC name 2-Sulfanylidene-2,3-dihydropyrimidin-4(1H)-one
Identifiers
CAS Number	141-90-2 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:348530 Y
ChEMBL	ChEMBL345768 Y
ChemSpider	1066108 Y
ECHA InfoCard	100.005.008
KEGG	C19304 Y
MeSH	Thiouracil
PubChem CID	1269845
UNII	59X161SCYL Y
CompTox Dashboard (EPA)	DTXSID4021347
InChI InChI=1S/C4H4N2OS/c7-3-1-2-5-4(8)6-3/h1-2H,(H2,5,6,7,8) Y Key: ZEMGGZBWXRYJHK-UHFFFAOYSA-N Y InChI=1/C4H4N2OS/c7-3-1-2-5-4(8)6-3/h1-2H,(H2,5,6,7,8) Key: ZEMGGZBWXRYJHK-UHFFFAOYAK
SMILES O=C1C=CNC(=S)N1
Properties
Chemical formula	C4H4N2OS
Molar mass	128.15 g·mol−1
Melting point	340 °C (644 °F; 613 K) decomposition
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Medical use

The substance is a historically relevant anti-thyroid preparation. Edwin Astwood used it in 1943 as therapy for Graves' disease for the first time.^[2][3][4]

Thiouracil inhibits thyroid activity by blocking the enzyme thyroid peroxidase.^[5] Its use in recent times has been replaced by advent of more potent and safer antithyroid drugs. It occurs in seeds of Brassica and Crucifera species. Thiouracil has been used as antithyroid, coronary vasodilator, and in congestive heart failure although its use has been largely supplanted by other drugs.^[6]