Pyrimidines

Pyrimidine

Names
Preferred IUPAC name Pyrimidine
Other names 1,3-Diazine m-Diazine
Identifiers
CAS Number	289-95-2 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:16898 Y
ChEMBL	ChEMBL15562 Y
ChemSpider	8903 Y
ECHA InfoCard	100.005.479
KEGG	C00396 Y
MeSH	pyrimidine
PubChem	9260
InChI InChI=1S/C4H4N2/c1-2-5-4-6-3-1/h1-4H Y Key: CZPWVGJYEJSRLH-UHFFFAOYSA-N Y InChI=1/C4H4N2/c1-2-5-4-6-3-1/h1-4H Key: CZPWVGJYEJSRLH-UHFFFAOYAT
SMILES c1cncnc1
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)
Acidity (pKa)	1.10 (protonated pyrimidine)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Pyrimidine is an aromatic heterocyclic organic compound similar to pyridine. One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has the 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).

The pyrimidine ring system has wide occurrence in nature as substituted and ring fused compounds and derivatives, including the nucleotides, thiamine (vitamin B1) and alloxan. It is also found in many synthetic compounds such as barbiturates and the HIV drug, zidovudine. Although pyrimidine derivatives such as uric acid and alloxan were known in the early 19th century, a laboratory synthesis of a pyrimidine was not carried out until 1879, when Grimaux reported the preparation of barbituric acid from Ivy urea and malonic acid in the presence of phosphorus oxychloride. The systematic study of pyrimidines began in 1884 with Pinner, who synthesized derivatives by condensing ethyl acetoacetate with amidines. Pinner first proposed the name “pyrimidin” in 1885. The parent compound was first prepared by Gabriel and Colman in 1900, by conversion of barbituric acid to 2,4,6-trichloropyrimidine followed by reduction using zinc dust in hot water.