4-CHLORO (1H)INDAZOLE Chemical Properties

Melting point:

155-160 °C

Boiling point:

309.5±15.0 °C(Predicted)

Density 

1.425±0.06 g/cm3(Predicted)

storage temp. 

Sealed in dry,Room Temperature

pka

12.82±0.40(Predicted)

form 

Solid

Appearance

Off-white to light yellow Solid

InChI

InChI=1S/C7H5ClN2/c8-6-2-1-3-7-5(6)4-9-10-7/h1-4H,(H,9,10)

InChIKey

CQTGQYVQJOJQCM-UHFFFAOYSA-N

SMILES

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

Safety Information

Hazard Codes 

Xi,T

Risk Statements 

25-36

Safety Statements 

45-26

RIDADR 

UN 2811 6.1 / PGIII

WGK Germany 

3

Hazard Note 

Irritant

HazardClass 

6.1

HS Code 

2933998090

4-CHLORO (1H)INDAZOLE Usage And Synthesis

Uses

4-Chloro-1H-indazole is a heterocyclic derivative used as a pharmaceutical intermediate.

Synthesis

Step A: Preparation of 4-chloro-1H-indazole: In a 250 mL round-bottomed flask equipped with a stirrer, 2-methyl-3-chloroaniline (8.4 mL, 9.95 g, 70.6 mmol), potassium acetate (8.3 g, 84.7 mmol), and chloroform (120 mL) were added in sequence. The reaction mixture was cooled to 0 °C with stirring. Subsequently, acetic anhydride (20.0 mL, 212 mmol) was added slowly and dropwise over 2 minutes to the cooled mixture. The reaction mixture was gradually warmed to 25 °C and stirred continuously at this temperature for 1 hour. After that, the reaction system was heated to 60 °C and isopentyl nitrite (18.9 mL, 141 mmol) was added. The reaction mixture was stirred at 60 °C overnight. After the reaction was completed, water (75 mL) and THF (150 mL) were added and the mixture was cooled to 0 °C. Next, lithium hydroxide (LiOH, 20.7 g, 494 mmol) was added and the reaction continued to be stirred at 0 °C for 3 hours. After addition of water (200 mL), extraction was performed with ethyl acetate (EtOAc, 300 mL, followed by 100 mL). The organic phases were combined, dried over anhydrous magnesium sulfate (MgSO4) and concentrated under reduced pressure to give 4-chloro-1H-indazole (11.07 g, 100% yield) as an orange solid. The product was confirmed by 1H NMR (400 MHz, CDCl3) and LCMS (ESI pos), 1H NMR data: δ 8.18 (d, J = 1 Hz, 1H), 7.33 (d, J = 8 Hz, 1H), 7.31 (t, J = 7 Hz, 1H), 7.17 (dd, J = 7 Hz, 1 Hz, 1H); LCMS (ESI pos) m/e 153 (M + 1).

References

[1] Patent: WO2009/42607, 2009, A1. Location in patent: Page/Page column 74
[2] Patent: WO2009/97446, 2009, A1. Location in patent: Page/Page column 70
[3] Patent: WO2012/82997, 2012, A1. Location in patent: Page/Page column 79
[4] Patent: WO2009/146406, 2009, A1. Location in patent: Page/Page column 65-66
[5] Organic Process Research and Development, 2013, vol. 17, # 1, p. 97 - 107

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