Pyrazole-3-boronic acid Chemical Properties

Melting point:

85-88°C

Boiling point:

430.4±37.0 °C(Predicted)

Density 

1.40±0.1 g/cm3(Predicted)

storage temp. 

Inert atmosphere,Store in freezer, under -20°C

form 

solid

pka

8.58±0.53(Predicted)

color 

Off-white

Water Solubility 

Soluble in water.

InChI

InChI=1S/C3H5BN2O2/c7-4(8)3-1-2-5-6-3/h1-2,7-8H,(H,5,6)

InChIKey

NEUWPDLMDVINSN-UHFFFAOYSA-N

SMILES

N1C=CC(B(O)O)=N1

Safety Information

Hazard Codes 

Xi

Risk Statements 

36/37/38

Safety Statements 

26-36/37

WGK Germany 

3

HazardClass 

IRRITANT

HS Code 

2933199090

Pyrazole-3-boronic acid Usage And Synthesis

Uses

Significantly used as synthetic intermediates. They are widely used in the production of optics.

Synthesis

General procedure for the synthesis of 1H-pyrazole-3-boronic acid from 1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazole: To a solution of 1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazole (7.6 g, 52 mmol) in tetrahydrofuran (THF, 50 mL) was added slowly at -78 °C n-butyllithium (n-BuLi, 33 mL, 2.5 M hexane solution, 82.5 mmol), followed by the addition of triisopropylborane (12.7 mL, 55 mmol) dropwise, keeping the reaction temperature at -70 °C. The reaction mixture was stirred at -70 °C for 1 hour and then slowly warmed to room temperature over 4 hours. After completion of the reaction, the reaction was quenched with 2M hydrochloric acid (HCl) and the solvent was removed under vacuum. The pH of the reaction mixture was adjusted to 6 with 1M sodium hydroxide (NaOH) solution, at which time a precipitate was formed. The precipitate was collected by filtration, washed sequentially with toluene and petroleum ether, and finally ground with ethyl acetate to afford 1H-pyrazole-3-boronic acid as a white solid (2.7 g, 48% yield), and the product could be used in subsequent reactions without further purification.

References

[1] Patent: WO2007/138072, 2007, A2. Location in patent: Page/Page column 55
[2] Journal of Medicinal Chemistry, 2004, vol. 47, # 12, p. 2995 - 3008

Pyrazole-3-boronic acid(376584-63-3)Related Product Information

• Ethyl 2-(Chlorosulfonyl)acetate
• Pyraclostrobin
• Pyrazole
• Folic acid
• Glycine
• Zolpidem tartrate
• 5-Methyl-2-phenyl-1,2-dihydropyrazol-3-one
• 3-(4,4,5,5-TETRAMETHYL-1,3,2-DIOXABOROLANE)-PYRAZOLE
• Dimethyl 1H-pyrazole-3,5-dicarboxylate
• 5-Pyrazolecarboxylic acid
• 4-CYANOPYRAZOLE
• Methyl Pyrazole-3-carboxylate
• DIETHYL 3,5-PYRAZOLEDICARBOXYLATE
• 1H-PYRAZOLE-3-CARBONITRILE
• Pyrazinoic acid hydrazide
• Boric acid
• 1-(Tetrahydropyran-2-yl)-1H-pyrazole-5-boronic acid pinacol ester
• 5-(5,5-DIMETHYL-1,3,2-DIOXABORINAN-2-YL)-1-METHYL-1H-PYRAZOLE