Pyridazine

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Pyridazine
Skeletal formula with numbering convention
Pyridazine molecule
Pyridazine molecule
Names
Preferred IUPAC name
Pyridazine[1]
Systematic IUPAC name
1,2-Diazabenzene
Other names
1,2-Diazine
Orthodiazine
Oizine
Identifiers
  • 289-80-5 checkY
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.005.478 Edit this at Wikidata
EC Number
  • 206-025-5
UNII
Properties
C4H4N2
Molar mass 80.090 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)
miscible
Solubility miscible in dioxane, ethanol
soluble in benzene, diethyl ether
negligible in cyclohexane, ligroin
1.52311 (23.5 °C)
Thermochemistry
Std enthalpy of
formation (ΔfH⦵298)
 224.9 kJ/mol
Hazards
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 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.[2] 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 , and . It is also found within the structure of several drugs such as cefozopran, cadralazine, minaprine, pipofezine, and hydralazine.

Synthesis[]

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.[3] 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.[4]

References[]

  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. ^ Gumus, S. (2011). "A computational study on substituted diazabenzenes" (PDF). Turk J Chem. 35: 803–808. Archived from the original (PDF) on 2016-03-03. Retrieved 2014-04-10.
  3. ^ Fischer, E. (1886). "Indole aus Phenylhydrazin". Justus Liebigs Annalen der Chemie. 236 (1–2): 126–151. doi:10.1002/jlac.18862360107.
  4. ^ Tišler, M.; Stanovnik, B. (1968). "Pyridazines". Advances in Heterocyclic Chemistry. 9: 211–320. doi:10.1016/S0065-2725(08)60374-8. ISBN 9780120206094.
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