Title: Pyridazine
CAS Registry Number: 289-80-5
CAS Name: 1,2-Diazine
Additional Names: orthodiazine; oizine
Molecular Formula: C4H4N2
Molecular Weight: 80.09
Percent Composition: C 59.99%, H 5.03%, N 34.98%
Literature References: Prepd from maleic hydrazide: Mizzoni, Spoerri, J. Am. Chem. Soc. 73, 1873 (1951). Resonance energy and position of double bonds: Maccoll, J. Chem. Soc. 1946, 671.
Properties: Liquid. d418 1.107; d423.5 1.1035. mp -8°. bp760 208°; bp14 87°; bp1.0 48°. nD23.5 1.52311. Dipole moment in dioxane at 35° = 3.94. uv max: 338 nm. Resonance energy: 22 kcal. Miscible with water, benzene, DMF. Freely sol in methanol, ethanol, ether. Practically insol in petr ether.
Melting point: mp -8°
Boiling point: bp760 208°; bp14 87°; bp1.0 48°
Index of refraction: nD23.5 1.52311
Absorption maximum: uv max: 338 nm
Density: d418 1.107; d423.5 1.1035
Derivative Type: Hydrochloride
Molecular Formula: C4H4N2.HCl
Molecular Weight: 116.55
Percent Composition: C 41.22%, H 4.32%, N 24.04%, Cl 30.42%
Properties: Yellow solid, mp 161-163°.
Melting point: mp 161-163°
Pyridine Pyridine 1-Oxide Pyridinium Bromide Perbromide Pyridinium Chlorochromate Pyridinol Carbamate

Skeletal formula with numbering convention
Pyridazine molecule Pyridazine molecule
CAS number 289-80-5 YesY
PubChem 9259
ChemSpider 8902 YesY
ChEBI CHEBI:30954 YesY
RTECS number GY2390000
Jmol-3D images Image 1
Molecular formula C4H4N2
Molar mass 80.09 g mol−1
Appearance colorless liquid
Density 1.107 g/cm3
Melting point −8 °C; 18 °F; 265 K
Boiling point 208 °C; 406 °F; 481 K
Related compounds
Related compounds pyridine, pyrimidine, pyrazine
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Pyridazine is a heterocyclic organic compound with the molecular formula (CH)4N2. It contains a six-membered ring with two adjacent nitrogen atoms. It is a colorless liquid with a boiling point of 208 °C. It is isomeric with two other (CH)4N2 rings, pyrimidine and pyrazine.