1: 95 percent / conc. H2SO4 / 1,2-dichloro-ethane / 1.5 h / Heating 2: dimethylformamide / 9 h / 160 - 163 °C 3: Fe powder / ethanol; acetic acid / 0.5 h / 80 - 85 °C 4: 47 percent / 2,3-dichloro-5,6-dicyano-1,4-benzoquinone / benzene / 16 h / Ambient temperature View Scheme

1: 95 percent / conc. H2SO4 / 1,2-dichloro-ethane / 1.5 h / Heating 2: dimethylformamide / 9 h / 160 - 163 °C 3: Fe powder / ethanol; acetic acid / 0.5 h / 80 - 85 °C 4: 68 percent / Cu2Br2, Na2CO3 / various solvent(s) / 5.5 h / 170 °C 5: 81 percent / 2,3-dichloro-5,6-dicyano-1,4-benzoquinone / benzene / 6 h / Heating View Scheme