Pyridazine

Pyridazine
C=black, H=white, N=blue	C=black, H=white, N=blue
Names
	Preferred IUPAC name Pyridazine
	Systematic IUPAC name 1,2-Diazabenzene
	Other names 1,2-Diazine; Orthodiazine; Oizine
Identifiers
CAS Number	289-80-5;
3D model (JSmol)	Interactive image;
Beilstein Reference	103906
ChEBI	CHEBI:30954;
ChEMBL	ChEMBL15719;
ChemSpider	8902;
ECHA InfoCard	100.005.478
EC Number	206-025-5;
Gmelin Reference	49310
PubChemCID	9259;
UNII	449GLA0653;
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 n1ncccc1;
Properties
Chemical formula	C4H4N2
Molar mass	80.090g·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)
Solubility in water	miscible
Solubility	miscible indioxane,ethanol; soluble inbenzene,diethyl ether; negligible incyclohexane,ligroin
Refractive index(nD)	1.52311 (23.5 °C)
Thermochemistry
Std enthalpy of; formation(ΔfH⦵298)	224.9 kJ/mol
Hazards
	GHSlabelling:
Pictograms
Signal word	Warning
Hazard statements	H302,H315,H319,H335
Precautionary statements	P261,P264,P264+P265,P270,P271,P280,P301+P317,P302+P352,P304+P340,P305+P351+P338,P319,P321,P330,P332+P317,P337+P317,P362+P364,P403+P233,P405,P501
Flash point	85 °C (185 °F; 358 K)
Related compounds
Related compounds	pyridine; pyrimidine; pyrazine;
	Except where otherwise noted, data are given for materials in theirstandard state(at 25 °C [77 °F], 100 kPa). verify(what is?) Infobox references

Pyridazineis anaromatic,heterocyclic,organic compoundwith the molecular formulaC₄H₄N₂.It contains a six-memberedringwith two adjacentnitrogenatoms.^[3]It is a colorless liquid with aboiling pointof 208 °C. It isisomericwith two otherdiazine(C₄H₄N₂) rings,pyrimidineandpyrazine.

Occurrence

Pyridazines are rare in nature, possibly reflecting the scarcity of naturally occurringhydrazines,common building blocks for the synthesis of these heterocycles. The pyridazine structure is a popularpharmacophorewhich is found within a number of herbicides such ascredazine,pyridafolandpyridate.It is also found within the structure of several drugs such ascefozopran,cadralazine,minaprine,pipofezine,andhydralazine.

Synthesis

In the course of his classic investigation on theFischer indole synthesis,Emil Fischer prepared the first pyridazine via the condensation ofphenylhydrazineandlevulinic acid.^[4]The parent heterocycle was first prepared by oxidation ofbenzocinnolineto the pyridazinetetracarboxylic acid followed bydecarboxylation.A better route to this otherwise esoteric compound starts with themaleic hydrazide.These heterocycles are often prepared via condensation of 1,4-diketonesor 4-ketoacids withhydrazines.^[5]

References

^"Front Matter".Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book).Cambridge:The Royal Society of Chemistry.2014. p. 141.doi:10.1039/9781849733069-FP001.ISBN 978-0-85404-182-4.
^"Pyridazine".pubchem.ncbi.nlm.nih.gov.
^Gumus, S. (2011)."A computational study on substituted diazabenzenes"(PDF).Turk J Chem.35:803–808. Archived fromthe original(PDF)on 2016-03-03.Retrieved2014-04-10.
^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 Volume 9.Vol. 9. pp. 211–320.doi:10.1016/S0065-2725(08)60374-8.ISBN 9780120206094.

[iupac2013-1] "Front Matter".Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book).Cambridge:The Royal Society of Chemistry.2014. p. 141.doi:10.1039/9781849733069-FP001.ISBN 978-0-85404-182-4.

[2] "Pyridazine".pubchem.ncbi.nlm.nih.gov.

[3] Gumus, S. (2011)."A computational study on substituted diazabenzenes"(PDF).Turk J Chem.35:803–808. Archived fromthe original(PDF)on 2016-03-03.Retrieved2014-04-10.

[4] Fischer, E. (1886)."Indole aus Phenylhydrazin".Justus Liebigs Annalen der Chemie.236(1–2): 126–151.doi:10.1002/jlac.18862360107.

[5] Tišler, M.; Stanovnik, B. (1968). "Pyridazines".Advances in Heterocyclic Chemistry Volume 9.Vol. 9. pp. 211–320.doi:10.1016/S0065-2725(08)60374-8.ISBN 9780120206094.

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