1: 1) 5percent sodium nitrite / 1) 2N H2SO4, 50 deg C, 2) 2N H2SO4, 2 h, reflux 2: 850 mg / 15percent H2O2 / 80 °C 3: 110 mg / potassium chromate / 70 °C 4: 23 mg / methanol / 96 h / 40 - 45 °C View Scheme