1: 80 percent / 85percent hydrazine hydrate / ethanol / 2.5 h / Heating 2: 76 percent / potassium carbonate / toluene / 2 h / Heating 3: 94 percent / conc. sulfuric acid / 24 h / Heating 4: 53.5 percent / 50percent NaH / toluene / 8 h / 110 °C View Scheme