Pyrazole Chemical Properties

Melting point:

67-70 °C (lit.)

Boiling point:

186-188 °C (lit.)

Density 

1.4088 (rough estimate)

vapor pressure 

21Pa at 20℃

refractive index 

1.4203

Flash point:

186-188°C

storage temp. 

Store below +30°C.

solubility 

Chloroform, Methanol

form 

Crystals or Crystalline Powder

pka

2.49(at 25℃)

color 

White to yellow

Water Solubility 

SOLUBLE

Sensitive 

Hygroscopic

Merck 

14,7960

BRN 

103775

InChIKey

WTKZEGDFNFYCGP-UHFFFAOYSA-N

LogP

0.33 at 25℃

CAS DataBase Reference

288-13-1(CAS DataBase Reference)

NIST Chemistry Reference

1H-Pyrazole(288-13-1)

EPA Substance Registry System

Pyrazole (288-13-1)

Safety Information

Hazard Codes 

Xn

Risk Statements 

22-36/37/38-52-20/21/22

Safety Statements 

26-36/37-61-37/39-36

RIDADR 

2811

WGK Germany 

1

RTECS 

UQ4900000

TSCA 

Yes

HazardClass 

6.1(b)

PackingGroup 

III

HS Code 

29331990

Toxicity

LD50 (24 hr) in rats, mice (mmol/kg): 19, 21 i.v.; 21, 22 orally (Magnussen)

MSDS

• Language:English Provider:1H-Pyrazole
• Language:English Provider:SigmaAldrich
• Language:English Provider:ACROS
• Language:English Provider:ALFA

Pyrazole Usage And Synthesis

Chemical Properties

white to yellow crystals or crystalline powder

Uses

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.]

Pyrazole(288-13-1)Related Product Information

• Zolpidem tartrate
• 3-Aminopyrazole
• 3,5-Dimethylpyrazole
• Pyrazine
• Praziquantel
• Dimethyl 1H-pyrazole-3,5-dicarboxylate
• 3-(4,4,5,5-TETRAMETHYL-1,3,2-DIOXABOROLANE)-PYRAZOLE
• 5-Pyrazolecarboxylic acid
• 4-CYANOPYRAZOLE
• Methyl Pyrazole-3-carboxylate
• Pyrazole-3-boronic acid
• DIETHYL 3,5-PYRAZOLEDICARBOXYLATE
• 1H-PYRAZOLE-3-CARBONITRILE
• DIALLYLAMINE HYDROCHLORIDE
• ACID ORANGE 63
• 3-Amino-4-pyrazolecarbonitrile
• Zolpidem
• 4-Aminoantipyrine