1: 88 percent / 2N HNO3 / H2O / pH = 2-3 2: 77 percent / sodium-amalgan / methanol; H2O / 22 h / Ambient temperature 3: 1) 5percent sodium nitrite, 2) 2N H2SO4 / 1) 2N H2SO4, 50 deg C, 5 min, 2) 1 h, reflux View Scheme