1: 95 percent / 90percent aq. H2SO4 / 0.25 h / 140 °C 2: 94 percent / conc. HNO3, NaNO2 / acetic acid / 0.5 h 3: 96 percent / triethylamine, phosphoryl chloride / 1 h / Heating 4: 96 percent / pyridine / various solvent(s) / 0.5 h / Ambient temperature View Scheme

sulfuric acid T=140°C; 0.25 h;

sodium hydroxide in water; ethylene glycol 1 h; Heating;

1: 83 percent / diphenyl ether / 5 h / Heating 2: 91 percent / NaOH / ethane-1,2-diol; H2O / 1 h / Heating View Scheme

sodium hydroxide Heating;