Guanidine Nitrate

Typical Procedure:
To a well-stirred mixture of aromatic compound (0.01 mol) and 85% sulfuric acid (15 mL) is slowly added guanidine nitrate (1.22 g, 0.01 mol) while maintaining the temperature at 0-5 ℃. After the addition of guanidine nitrate is complete, the mixture is stirred for an additional 0.5-3 h at the same temperature or at rt (for Entry 4). The reaction mixture is poured onto ice water (100 mL) and in the case of Entry 3, it is poured onto ice cold 20% NaOH solution (100 mL). The solid obtained is filtered, washed thoroughly with water and dried. Where solid is not obtained, the aqueous layer is extracted with CHCl₃ (4 x 50 mL). The combined CHCl₃ layer is washed with 10% Na₂CO₃ (2 x 25 mL), water (2 x 25 mL) and then dried (anhyd. Na₂SO₄). After evaporation of the solvent, a brown residue is obtained, which is purified by column chromatography to afford the corresponding nitro compound.