Pyrimidine

Pyrimidine
Names
	Preferred IUPAC name Pyrimidine
	Systematic IUPAC name 1,3-Diazabenzene
	Other names 1,3-Diazine; m-Diazine
Identifiers
CAS Number	289-95-2 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	103894
ChEBI	CHEBI:16898 ;
ChEMBL	ChEMBL15562 ;
ChemSpider	8903 ;
ECHA InfoCard	100.005.479
EC Number	206-026-0;
Gmelin Reference	49324
KEGG	C00396 ;
MeSH	pyrimidine
PubChem CID	9260;
UNII	K8CXK5Q32L ;
CompTox Dashboard (EPA)	DTXSID1051228 ;
	InChI InChI=1S/C4H4N2/c1-2-5-4-6-3-1/h1-4H Key: CZPWVGJYEJSRLH-UHFFFAOYSA-N ; InChI=1/C4H4N2/c1-2-5-4-6-3-1/h1-4H Key: CZPWVGJYEJSRLH-UHFFFAOYAT;
	SMILES n1cnccc1;
Properties
Chemical formula	C4H4N2
Molar mass	80.088 g mol−1
Density	1.016 g cm−3
Melting point	20 to 22 °C (68 to 72 °F; 293 to 295 K)
Boiling point	123 to 124 °C (253 to 255 °F; 396 to 397 K)
Solubility in water	Miscible (25°C)
Acidity (pKa)	1.10 (protonated pyrimidine)
Hazards
	GHS labelling:[1]
Pictograms
Signal word	Danger
Hazard statements	H226, H318
Precautionary statements	P210, P233, P240, P241, P242, P243, P264+P265, P280, P303+P361+P353, P305+P354+P338, P317, P370+P378, P403+P235, P501
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Pyrimidine (C₄H₄N₂; /pɪˈrɪ.mɪˌdiːn, paɪˈrɪ.mɪˌdiːn/) is an aromatic, heterocyclic, organic compound similar to pyridine (C₅H₅N). One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has nitrogen atoms at positions 1 and 3 in the ring. The other diazines are pyrazine (nitrogen atoms at the 1 and 4 positions) and pyridazine (nitrogen atoms at the 1 and 2 positions).

In nucleic acids, three types of nucleobases are pyrimidine derivatives: cytosine (C), thymine (T), and uracil (U).