Pyridazine

Pyridazine

Names
IUPAC name Pyridazine
Other names 1,2-diazine, orthodiazine, oizine
Identifiers
CAS Number	289-80-5 Y
ChEBI	CHEBI:30954 Y
ChEMBL	ChEMBL15719 Y
ChemSpider	8902 Y
Jmol interactive 3D	Image
PubChem	9259
RTECS number	GY2390000
InChI InChI=1S/C4H4N2/c1-2-4-6-5-3-1/h1-4H Y Key: PBMFSQRYOILNGV-UHFFFAOYSA-N Y InChI=1/C4H4N2/c1-2-4-6-5-3-1/h1-4H Key: PBMFSQRYOILNGV-UHFFFAOYAA
SMILES c1ccnnc1
Properties
Chemical formula	C4H4N2
Molar mass	80.09 g/mol
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
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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, and is aromatic.^[1] It is a colorless liquid with a boiling point of 208 °C. It is isomeric with two other (CH)₄N₂ rings, pyrimidine and pyrazine.

Occurrence

Pyridazines are rare in nature, possibly reflecting the scarcity of naturally occurring hydrazines, common building blocks for the synthesis of these heterocycles. The pyridazine structure is a popular pharmacophore which is found within a number of herbicides such as credazine, pyridafol and pyridate. It is also found within the structure of several drugs such as cefozopran, cadralazine, minaprine, pipofezine, hydralazine, and cilazapril.

Syntheses

In the course of his classic investigation on the Fischer indole synthesis, Emil Fischer prepared the first pyridazine via the condensation of phenylhydrazine and levulinic acid.^[2] The parent heterocycle was first prepared by oxidation of benzocinnoline to the pyridazinetetracarboxylic acid followed by decarboxylation. A better route to this otherwise esoteric compound starts with the maleic hydrazide. These heterocycles are often prepared via condensation of 1,4-diketones or 4-ketoacids with hydrazines.^[3]

References

1. ↑ Gumus, S. (2011). "A computational study on substituted diazabenzenes" (PDF). Turk J Chem 35: 803–808. 
2. ↑ Fischer, E. (1886). "Indole aus Phenylhydrazin". Justus Liebigs Annalen der Chemie 236 (1-2): 126–151. doi:10.1002/jlac.18862360107. 
3. ↑ Tišler, M.; Stanovnik, B. (1968). "Pyridazines". Advances in Heterocyclic Chemistry 9: 211–320. doi:10.1016/S0065-2725(08)60374-8.