1: 91 percent / N2H2*H2O / ethanol / 0 - 20 °C 2: 89 percent / 100 percent HNO3 / CH2Cl2 / 2 h / 0 °C View Scheme

1: 91 percent / N2H2*H2O / ethanol / 0 - 20 °C 2: 89 percent / 100 percent HNO3 / CH2Cl2 / 2 h / 0 °C 3: 80 percent / 96 percent H2SO4 / CH2Cl2 / -25 - 20 °C 4: 47 percent / 100 percent HNO3 / CH2Cl2 / 2 h / 0 °C View Scheme

1: 91 percent / N2H2*H2O / ethanol / 0 - 20 °C 2: 89 percent / 100 percent HNO3 / CH2Cl2 / 2 h / 0 °C 3: 80 percent / 96 percent H2SO4 / CH2Cl2 / -25 - 20 °C View Scheme