1: 50 percent / 1M aq. NaOH / methanol / 24 h / Ambient temperature 2: 70 percent / sulfur dichloride, pyridine / CHCl3 / 9 h / Ambient temperature 3: 72 percent / SOCl2, pyridine / CH2Cl2 / 0.5 h / 0 °C 4: 30 percent / H2O; CHCl3 / 4 h / Ambient temperature View Scheme