Pyrazole

Chemical properties

white to yellow crystals or crystalline powder

The Uses of Pyrazole

Pyrazole is used in organic synthesis and asa chelating agent.

Definition

ChEBI: 1H-pyrazole is the 1H-tautomer of pyrazole. It is a conjugate base of a pyrazolium. It is a conjugate acid of a pyrazol-1-ide. It is a tautomer of a 3H-pyrazole and a 4H-pyrazole.

General Description

Pyrazine is a heterocyclic crystalline aromatic compound with a five-membered ring containing three carbon atoms and two nitrogen atoms. It is a symmetricdiazine.

Hazard

Toxic by ingestion and inhalation, irritant to skin and eyes.

Health Hazard

The acute toxic symptoms from oral administrationof pyrazole in experimental animalswere ataxia, muscle weakness, and respiratorydepression. It is less toxic than pyrroleand pyrrolidine. The oral LD50 value in miceis within the range 1450 mg/kg.
Pyrazole exhibited reproductive toxicityin rats and mice when administered by oralor intraperitoneal route. The effects includefetal death, developmental abnormalities pertainingto the urogenital system, and postimplantationmortality.

Fire Hazard

Noncombustible solid.

Safety Profile

Moderately toxic by ingestion and intraperitoneal routes. Experimental teratogenic and reproductive effects. When heated to decomposition it emits toxic fumes of NOx.

Purification Methods

Crystallise pyrazole from pet ether, cyclohexane, or water. Its solubility in H2O at 9.6o is 2.7moles/L, and at 24.8o it is 19.4moles/L; in cyclohexane at 31.8o it is 0.577moles/L, and at 56.2o it is 5.86moles/L; and in benzene at 5.2o it is 0.31moles/L, and at 46.5o it is 16.8moles/1000mL. [Barszcz et al. J Chem Soc, Dalton Trans 2025 1986, Beilstein 23 H 39, 23 I 15, 23 II 33, 23 III/IV 550, 23/4 V 122.]