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|Molar mass||68.08 g mol−1|
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Pyrazole is the organic compound with the formula C3H3N2H. It is a heterocycle characterized by a 5-membered ring of three carbon atoms and two adjacent nitrogen centres. Pyrazoles are also the class of compounds that have the ring C3N2 with adjacent nitrogen centres. Notable drug that is a pyrazole is Celebrex.
Preparation and reactions
- CH3C(O)CH2C(O)CH3 + N2H4 → (CH3)2C3HN2H + 2 H2O
The term pyrazole was given to this class of compounds by German Chemist Ludwig Knorr in 1883. In a classical method developed by German chemist Hans von Pechmann in 1898, pyrazole was synthesized from acetylene and diazomethane.
Conversion to scorpionates
- KBH4 + 3 C3H3N2H → KBH(C3H3N2)3 + 3 H2
Occurrence and 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.
- Eicher, T.; Hauptmann, S. (2nd ed. 2003). The Chemistry of Heterocycles: Structure, Reactions, Syntheses, and Applications. Wiley-VCH. ISBN 3-527-30720-6.
- Review article (properties, biological activities, syntheses of pyrazoles): A. Schmidt, A. Dreger (2011). "Recent Advances in the Chemistry of Pyrazoles. Properties, Biological Activities, and Syntheses". Curr. Org. Chem 15 (9): 1423–1463. doi:10.2174/138527211795378263.
- William S. Johnson and Robert J. Highet (1963), "3,5-Dimethylpyrazole", Org. Synth.; Coll. Vol. 4: 351
- Pyrazol aus Acetylen und Diazomethan H. v. Pechmann Berichte der deutschen chemischen Gesellschaft Volume 31 Issue 3, Pages 2950–51, 1898 doi:10.1002/cber.18980310363
- Fowden; Noe, Ridd and White, (1959). Proc. Chem. SOC.,: 131.
- Noe, F F; L Fowden (1959). "alpha-Amino-beta-(pyrazolyl-N) propionic acid: a new amino-acid from Citrullus vulgaris (water melon)". Nature 184: 69–70. ISSN 0028-0836.