1.1: 86 percent / glacial acetic acid; sulfuric acid / H2O / 22 h / Heating 2.1: 77 percent / sulfuric acid / 5 h / Heating 3.1: 85 percent / perchloric acid / H2O / 16 h / 20 °C 4.1: sodium ethoxide / ethanol / 0.33 h / Heating 4.2: 56 percent / air / ethanol / 48 h / 20 °C View Scheme