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| Names | |||
|---|---|---|---|
| Preferred IUPAC name Pyridazine[1] | |||
| Systematic IUPAC name 1,2-Diazabenzene | |||
| Other names 1,2-Diazine Orthodiazine Oizine | |||
| Identifiers | |||
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3D model (JSmol) | |||
| 103906 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| ECHA InfoCard | 100.005.478 | ||
| EC Number |
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| 49310 | |||
| UNII | |||
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| 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 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 | |||
| GHS labelling:[2] | |||
 | |||
| Warning | |||
| H302,H315,H319,H335 | |||
| 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 | |||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Pyridazine is anaromatic,heterocyclic,organic compound with the molecular formulaC4H4N2. It contains a six-memberedring with two adjacentnitrogen atoms.[3] It is a colorless liquid with aboiling point of 208 °C. It isisomeric with two otherdiazine (C4H4N2) rings,pyrimidine andpyrazine.
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 popularpharmacophore which is found within a number of herbicides such ascredazine,pyridafol andpyridate. It is also found within the structure of several drugs such ascefozopran,cadralazine,minaprine,pipofezine, andhydralazine.
In the course of his classic investigation on theFischer indole synthesis, Emil Fischer prepared the first pyridazine via the condensation ofphenylhydrazine andlevulinic acid.[4] The parent heterocycle was first prepared by oxidation ofbenzocinnoline to 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-diketones or 4-ketoacids withhydrazines.[5]
