5-Hydroxy-1-methylpyrazole Chemical Properties

Melting point:

110-114 °C

Boiling point:

217.7±13.0 °C(Predicted)

Density 

1.22±0.1 g/cm3(Predicted)

storage temp. 

Inert atmosphere,Room Temperature

solubility 

soluble in DMSO, Methanol

form 

powder to crystal

pka

9.07±0.23(Predicted)

color 

White to Orange to Green

InChI

InChI=1S/C4H6N2O/c1-6-4(7)2-3-5-6/h2-3,7H,1H3

InChIKey

CMXOTACIOGGSNH-UHFFFAOYSA-N

SMILES

N1(C)C(O)=CC=N1

Safety Information

Hazard Codes 

Xn

Risk Statements 

22-37/38-41

Safety Statements 

26-39

WGK Germany 

3

HazardClass 

IRRITANT

HS Code 

2933199090

5-Hydroxy-1-methylpyrazole Usage And Synthesis

Uses

5-Hydroxy-1-methylpyrazole is a pyrazole derivative used as an intermediate in the preparation of herbicides.

Synthesis

The general procedure for the synthesis of 1-methyl-5-hydroxypyrazole-4-carboxylic acid from ethyl 1-methyl-5-hydroxypyrazole-4-carboxylate is as follows: 22 g of sodium hydroxide was dissolved in 300 mL of water, 42.5 g of intermediate (ethyl 1-methyl-5-hydroxypyrazole-4-carboxylate) was added, and the reaction was stirred for 3 hr at 40 °C, then cooled to room temperature. 55 mL of concentrated hydrochloric acid was added dropwise, followed by heating and refluxing for 3 hours. After completion of the reaction, the solvent was removed by distillation under reduced pressure, 200 mL of anhydrous ethanol was added to the residue, and the precipitate was collected by filtration after thorough stirring. The filtrate was concentrated under reduced pressure to give 24 g of white solid product (1-methyl-5-hydroxypyrazole) in 98.0% yield and 96.50% HPLC purity.

References

[1] Patent: CN105218449, 2016, A. Location in patent: Paragraph 0063; 006=5

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