氧化氮类硝化反应

氧化氮类化合物，也能使苯环硝化，如NO2-O3 , N 2O3 /BF3 , N2O4 /H2SO4 , N2O4 /AlCl3 , n-BuLi/N2O4 , N2O5 , N2O /HNO3 ，N2O5/SO2 等多种体系。这类方法产率高，对高度钝化的苯环也能得到比较好的结果，对多种杂环也有效。特别是NO2－O3 体系，由于不使用酸，所以对一些在强酸条件下不稳定的化合物比较适用。反应在温和条件下进行；缺点是操作不方便，一般情况下还是优先考虑其他硝化方法。

反应实例

1, 2, 4, 5-tetrachlorobenzene (1.08 g, 5 mmol) was dissolved in freshly distilled CH 2 Cl 2 (50 mL) and the solution was placed in a three-necked 50 mL flask fitted with two gas inlet tubes and a vent which permits waste gas to escape. The mixture was cooled to 0 o C in an ice bath, while a stream of ozonized oxygen was introduced under vigorous stirring through the gas inlet tube, which should dip just below the surface of the liquid in the flask. Nitrogen dioxide was slowly introduced from another tube, the opening of which should be placed just

above the surface of the solution. Under these conditions, the loss of nitrogen dioxide was not significant, so the passage of nitrogen dioxide may be stopped after the appropriate time. The progress of the reaction was monitored by TLC or GC. Then the cooling bath was removed and excess nitrogen dioxide expelled by blowing air into the solution. The reaction mixture was diluted with sat. aq NaHCO 3 , and the organic phase was separated, washed with water, dried over Na 2 SO 4 . The solvent was removed under reduced pressure, the residue

was purified by column chromatography to give the product (1.2 g, 92%).

【Suzuki, H; Mori, T; Maeda, K. Synthesis, 1994, 841】