5-Chloro-3-methylpyrazole Chemical Properties

Melting point:

118.5°C

Boiling point:

180.5°C (rough estimate)

Density 

1.2115 (rough estimate)

refractive index 

1.5320 (estimate)

storage temp. 

under inert gas (nitrogen or Argon) at 2-8°C

pka

11.60±0.10(Predicted)

Appearance

White to off-white Solid

EPA Substance Registry System

1H-Pyrazole, 3-chloro-5-methyl- (15953-45-4)

Safety Information

HazardClass 

IRRITANT

HS Code 

2933199090

5-Chloro-3-methylpyrazole Usage And Synthesis

Synthesis

General procedure for the synthesis of 5-chloro-3-methylpyrazole from 5-chloro-1,3-dimethyl-1H-pyrazole: (a) 5-chloro-1,3-dimethylpyrazole (2.6 mmol) and pyridine hydrochloride (13.1 mmol) were placed in a sealed 5 mL process vial, and the mixture was heated by microwave radiation for 2 hr at 200 °C. After completion of the reaction, it was cooled to room temperature, ethyl acetate (15 mL) was added, the mixture was washed sequentially with 2 M aqueous hydrochloric acid (10 mL) and saturated aqueous sodium chloride, dried over anhydrous magnesium sulphate and concentrated to give the title compound 5-chloro-3-methylpyrazole as a white solid (yield: 210 mg, 67%). Mass spectrometry (MS) showed molecular ion peak (M+H) m/z = 117. 1H-NMR (DMSO-d6, 400 MHz) data: δ 12.66 (broad single peak, 1H), 6.03 (multiple peaks, 1H), 2.19 (single peak, 3H).

References

[1] Patent: WO2007/45868, 2007, A1. Location in patent: Page/Page column 50
[2] Patent: WO2007/51981, 2007, A1. Location in patent: Page/Page column 47-48
[3] Patent: WO2006/32851, 2006, A1. Location in patent: Page/Page column 41-42
[4] Bioorganic and Medicinal Chemistry Letters, 2015, vol. 25, # 15, p. 3024 - 3029
[5] Patent: WO2008/129280, 2008, A1. Location in patent: Page/Page column 46

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