6-Hydroxyindazole Chemical Properties

Melting point:

217.0 to 221.0 °C

Boiling point:

366.5±15.0 °C(Predicted)

Density 

1.434±0.06 g/cm3(Predicted)

storage temp. 

Inert atmosphere,Room Temperature

solubility 

soluble in Methanol

form 

powder to crystal

pka

9.17±0.40(Predicted)

color 

Light yellow to Yellow to Orange

InChI

InChI=1S/C7H6N2O/c10-6-2-1-5-4-8-9-7(5)3-6/h1-4,10H,(H,8,9)

InChIKey

NUYZVDBIVNOTSC-UHFFFAOYSA-N

SMILES

N1C2=C(C=CC(O)=C2)C=N1

CAS DataBase Reference

23244-88-4

Safety Information

Hazard Codes 

Xn

Risk Statements 

22

WGK Germany 

3

RTECS 

NK8010000

HS Code 

2933998090

Toxicity

mouse,LD50,intravenous,180mg/kg (180mg/kg),U.S. Army Armament Research & Development Command, Chemical Systems Laboratory, NIOSH Exchange Chemicals. Vol. NX#04549,

6-Hydroxyindazole Usage And Synthesis

Uses

6-Hydroxyinazole is a light brown powder and an important pharmaceutical intermediate used to construct the core of active drug molecules. It has broad application prospects in the synthesis and screening of small molecule chemical drugs. 6-Hydroxyinazole has neuroprotective effects. Indazole and its derivatives possess various biological activities, such as anti-inflammatory, antitumor, antioxidant, hypoglycemic, anti-HIV, anti-tuberculosis, antiplatelet, and 5-HT3 receptor antagonism. In addition, indazole derivatives are widely used in herbicides and dyes. Indazole was originally defined as a "pyrazole-ringed benzene ring," belonging to the azole family. It contains only three elements: carbon, hydrogen, and oxygen, and is an aromatic heterocycle containing 10 electrons. Theoretically, depending on whether there are hydrogen atoms on the two nitrogen atoms, indazole exists in two tautomeric forms: 1H-indazole and 2H-indazole. When there are no substituents on the indazole, it mainly exists in the 1H-indazole form.

Chemical Properties

light brown powder

Synthesis

General procedure for the synthesis of 6-hydroxyindazole from 6-aminoindazole: 6-aminoindazole (2.66 g, 20 mmol) was added to 20% dilute sulfuric acid and the reaction was carried out under microwave radiation (600 W, 170°C) for 1 hour. After completion of the reaction, the reaction solution was cooled and the pH was adjusted to 7 with 5% NaOH solution and stirred for 10 min to precipitate. The precipitate was recrystallized from water to give 1.5 g of 6-hydroxyindazole in 51% yield. Subsequently, 6-hydroxyindazole and 3-(1-(4-chlorobutyl)-4-piperidinyl)-6-fluorobenzisoxazole were used as raw materials and reacted according to step 4 in the method for the preparation of IV-1 to obtain 6-[4-(4-(4-(3-(6-fluorobenzisoxazolyl))-1-piperazinyl)-n-butoxy]-(1H)-indazole in 62% yield. Elemental analysis result: C23H23FN4O2 (calculated value %: C 66.99, H 5.88, N 14.20; measured value: C 66.71, H 5.80, N 13.89).1H NMR (DMSO-d6) data: δ 8.21-6.49 (6H, aryl ring-H), 4.18-4.19 (2H, piperazinyl-H), 3.87 ( m, 5H, O-CH2), 3.66-3.75 (2H, piperazine-H), 3.25-3.54 (m, 6H), 2.79 (t, J=8 Hz, 2H), 2.42 (t, J=8 Hz, 2H), 1.71-1.90 (m, 4H). Mass spectral data: m/z 394.

References

[1] Bioorganic and Medicinal Chemistry, 2015, vol. 23, # 21, p. 6855 - 6868
[2] Patent: CN104876912, 2017, B. Location in patent: Paragraph 0047; 0201-0204
[3] Journal of Medicinal Chemistry, 2010, vol. 53, # 5, p. 2324 - 2328
[4] Patent: WO2004/39796, 2004, A1. Location in patent: Page/Page column 60-61
[5] Patent: WO2013/169964, 2013, A1. Location in patent: Paragraph 00369; 00370

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