Pyrazole
| |||
| Names | |||
|---|---|---|---|
| IUPAC name
Pyrazole
| |||
| Other names
1,2-Diazole
| |||
| Identifiers | |||
3D model (JSmol)
|
|||
| ChemSpider | |||
| ECHA InfoCard | 100.005.471 | ||
CompTox Dashboard (EPA)
|
|||
| |||
| Properties | |||
| C3H4N2 | |||
| Molar mass | 68.079 g·mol−1 | ||
| Melting point | 66-70 °C | ||
| Boiling point | 168-188 °C | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |||
Pyrazole refers both to the class of simple aromatic ring organic compounds of the heterocyclic series characterized by a 5-membered ring structure composed of three carbon atoms and two nitrogen atoms in adjacent positions, and to the unsubstituted parent compound. Being so composed and having pharmacological effects on humans, they are classified as alkaloids, although they are rare in nature.[1] In 1959, the first natural pyrazole, 1-pyrazolyl-alanine, was isolated from seeds of watermelons. The term pyrazole was given to this class of compounds by Ludwig Knorr in 1883.
Reactions
- In a classical method developed by H. Pechmann in 1898, pyrazole can be synthesized from acetylene and diazomethane.[2]
- Pyrazoles are produced synthetically through the reaction of α,β-unsaturated aldehydes with hydrazine and subsequent dehydrogenation:
- Pyrazoles react with potassium borohydride to form a class of ligands known as scorpionates.
- Structurally related compounds are pyrazoline and pyrazolidine.
Uses
In medicine, derivatives of pyrazoles are used for their analgesic, anti-inflammatory, antipyretic, antiarrhythmic, tranquilizing, muscle relaxing, psychoanaleptic, anticonvulsant, monoamineoxidase inhibiting, antidiabetic and antibacterial activities.
See also
- Imidazole, an analog with two non-adjacent nitrogen atoms
- Oxazole, an analog with the nitrogen atom in position 1 replaced by oxygen
- Pyrrole, an analog with only one nitrogen atom, in position 1
- Pyrazolone
- Simple aromatic rings
References
- ^
Eicher, T.; Hauptmann, S. (2nd ed. 2003). The Chemistry of Heterocycles: Structure, Reactions, Syntheses, and Applications. Wiley-VCH. ISBN 3527307206.
{{cite book}}: Check date values in:|date=(help)CS1 maint: multiple names: authors list (link) - ^ Pyrazol aus Acetylen und Diazomethan H. v. Pechmann Berichte der deutschen chemischen Gesellschaft Volume 31 Issue 3, Pages 2950 - 2951 1898 doi:10.1002/cber.18980310363