Ethanol → HCID 178419588, compound

Participants

Reaction Steps

2.0 g of 3-(3,4-dimethoxy-5-nitrophenyl)-1-methylpyrazol-5-ol are suspended in 100 ml of methylene chloride. After cooling to -40° a solution of 4.9 ml of boron tribromide in 60 ml of methylene chloride is added dropwise thereto within 1 hour. The mixture is subsequently stirred at room temperature for 16 hours, cooled to -20° and treated within 30 minutes with 100 ml of ethanol. After stirring at room temperature for 1 hour, the solvent is removed by distillation in a water-jet vacuum at 40°. The residue is treated three times with a mixture of 100 ml of ethanol/toluene each time, with the solvent being distilled each time. The residue is recrystallized from ethanol. There is obtained 5-(5-hydroxy-1-methylpyrazol-3-yl)-3-nitropyrocatechol hydrobromide in the form of yellow crystals of m.p.>250°.

Provenance & Evidence