Report on two preparation methods of 3-fluoro-2-nitropyridine_Industrial Additives

Background and overview of two preparation methods of 3-fluoro-2-nitropyridine

3-Fluoro-2-nitropyridine is an organic intermediate that can be prepared from 3-amino-2-nitropyridine through diazotization reaction.

Two preparation methods of 3-fluoro-2-nitropyridine reported

Report on two preparation methods of 3-fluoro-2-nitropyridine 1.

A solution of sodium nitrite (503.4 mg, 73 mmol) in H2O (1.0 mL) was added dropwise to 3-amino-2-nitropyridine (1.05 g, 73 mmol) in 34% fluoroboric acid (3.5 mL ) in the stirred mixture. During the addition, the temperature was maintained between -8°C and -2°C. The reaction mixture was stirred at room temperature for 30 minutes. The suspension was filtered and the solid was washed with 34% fluoroboric acid (20 mL) and diethyl ether (10 mL) and dried under vacuum overnight to provide the fluoroborate salt. The fluoroborate was refluxed in toluene (50 mL) for 3 h, treated with 10% NaHCO3, and extracted three times with CHCl3. The combined extracts were dried over Na2SO4, filtered and concentrated to provide 30 mg (2.8%) of 3-fluoro-2-nitropyridine.

Two preparation methods of 3-fluoro-2-nitropyridine report 2,

A solution of sodium nitrite (20 g, 288 mmol) in water (40 mL) was added dropwise to 3-amino-2-nitropyridine (40 g, 288 mmol) in 34% fluoroboric acid (140 mL ) in the stirred mixture. During the addition, the dimethyl sulfoxide temperature was maintained between -8°C and -2°C for formaldehyde furan. After 0.5 h, the suspension was filtered and the solid was washed with 34% fluoroboric acid (35 mL), diethyl ether (80 mL) and dried under high vacuum at room temperature for 12 h, yielding 52 g of fluoroborate in orange-brown color. solid salt. The dry solid decomposes by heating to 120°C. After decomposition, the remaining oil was treated with 10% sodium bicarbonate (80 mL) solution and the mixture was extracted with dichloromethane. The combined extracts were dried over sodium sulfate, filtered and the solvent was removed under reduced pressure to give the title compound as a pale yellow solid.

References

[1] From PCT Int. Appl., 2008109613, 12 Sep 2008

[2] From PCT Int. Appl., 2006044355, 27 Apr 2006