4-Bromo-1-ethyl-1H-pyrazole Chemical Properties

Boiling point:

108°C/20mmHg(lit.)

Density 

1.57±0.1 g/cm3(Predicted)

refractive index 

1.5170 to 1.5210

storage temp. 

2-8°C

form 

clear liquid

pka

0.23±0.10(Predicted)

color 

Light orange to Yellow to Green

InChI

InChI=1S/C5H7BrN2/c1-2-8-4-5(6)3-7-8/h3-4H,2H2,1H3

InChIKey

IPMSARLBJARXSC-UHFFFAOYSA-N

SMILES

N1(CC)C=C(Br)C=N1

Safety Information

Hazard Codes 

Xi

HS Code 

2933199090

4-Bromo-1-ethyl-1H-pyrazole Usage And Synthesis

Synthesis

a) Synthesis of 4-bromo-1-ethyl-1H-pyrazole: To a DMF solution of 4-bromo-1H-pyrazole (5 g, 34 mmol) was added potassium carbonate (K2CO3, 11.75 g, 85.03 mmol, 2.5 equiv) and ethyl iodide (8 g, 51 mmol, 1.5 equiv). The reaction mixture was stirred at room temperature for 12 hours. Upon completion of the reaction, a quench and extraction operation was performed as in Intermediate Example 5(c). The solvent was removed by distillation and the crude product obtained was purified by column chromatography (60-120 mesh silica gel, 40% ethyl acetate in hexane solution as eluent), resulting in the target product 1-ethyl-4-bromopyrazole in 84% (5 g) yield. The structure of the product was confirmed by 1H NMR (300 MHz, DMSO-d6) and LC-MS (ESI): 1H NMR (300 MHz, DMSO-d6) δ 8.02 (s, 1H), 7.55 (s, 1H), 4.15 (q, 2H), 1.37 (t, 3H); LC-MS (ESI): calculated mass: 175.03; Measured mass: 177.0 [M + H]+ (retention time: 0.56 min).

References

[1] Patent: WO2013/53983, 2013, A1. Location in patent: Page/Page column 36
[2] Patent: US2015/11548, 2015, A1. Location in patent: Paragraph 0150
[3] Patent: WO2015/92713, 2015, A1. Location in patent: Page/Page column 403
[4] Patent: WO2015/77503, 2015, A1. Location in patent: Paragraph 00341
[5] Patent: US9051320, 2015, B1. Location in patent: Paragraph 0258

4-Bromo-1-ethyl-1H-pyrazole(71229-85-1)Related Product Information

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• 4-BROMO-1-(4-METHYLBENZYL)-1H-PYRAZOLE-5-CARBOXALDEHYDE
• 4-BROMO-1-(4-CHLOROBENZYL)-1H-PYRAZOLE-5-CARBALDEHYDE
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