4-Pyrimidone

Names
Preferred IUPAC name 1H-Pyrimidin-6-one
Other names Hydroxypyrimidine; Pyrimidinone
Identifiers
CAS Number	557-01-7 2-Pyrimidone Y 4562-27-0 4-Pyrimidone Y[CAS]
3D model (JSmol)	Interactive image
ChemSpider	61686 2-Pyrimidone 19489 4-Pyrimidone
PubChem CID	20695
UNII	13K708ILY4 2-Pyrimidone Y K43V90OY4L 4-Pyrimidone Y
SMILES O=C1NC=NC=C1
Properties
Chemical formula	C4H4N2O
Molar mass	96.089 g·mol−1
Appearance	White to light yellow powder
Melting point	163 to 168 °C (325 to 334 °F; 436 to 441 K)
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Respiratory system, eye, skin irritation
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Pyrimidone is the name given to either of two heterocyclic compounds with the formula C₄H₄N₂O: 2-pyrimidone and 4-pyrimidone. The compounds can also be called 2-hydroxypyrimidine or 4-hydroxypyrimidine respectively, based on a substituted pyrimidine, or 1,3-diazine, ring.

Derivatives of pyrimidone are the basis of many other biological molecules, including:

• Nucleobases, such as cytosine
• Barbiturates, such as metharbital

• 
  Cytosine
• 
  Metharbital

• Antiulcer drugs including temelastine, icotidine, donetidine, and lupitidine.