1: 96 percent / conc. hydrochloric acid / 10 h / Ambient temperature 2: 93 percent / KMnO4 / acetone / Heating 3: 89 percent / H2NNH2/KOH / bis-(2-hydroxy-ethyl) ether 4: 65 percent / 70percent aq. HNO3, NaNO2 / 5 h / 70 °C View Scheme