Pyridazine

Pyridazine
C=black, H=white, N=blue	C=black, H=white, N=blue
Names
	IUPAC name Pyridazine
	Other names 1,2-diazine, orthodiazine, oizine
Identifiers
CAS Number	289-80-5 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:30954 ;
ChEMBL	ChEMBL15719 ;
ChemSpider	8902 ;
ECHA InfoCard	100.005.478
PubChem CID	9259;
RTECS number	GY2390000;
CompTox Dashboard (EPA)	DTXSID7059777 ;
	InChI InChI=1S/C4H4N2/c1-2-4-6-5-3-1/h1-4H Key: PBMFSQRYOILNGV-UHFFFAOYSA-N ; 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). verify (what is ?) 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, and hydralazine.

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

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

[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.

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