1: 93 percent / Dowex 50W-X8(H+), H2S(gas) / methanol / 1 h / 0 °C 2: 50.7 percent / pyridine / methanol / 16 h / Ambient temperature 3: 50 percent / concd. HCl, 50percent aq. hypophosphorus acid, NaNO2 / H2O / 1 h / 0 °C 4: 86 percent / NH3(gas) / methanol / 24 h / 22 °C View Scheme

in methanol 17 h; Ambient temperature;

1: 100 percent / Dowex 50W-X8(H+), H2Se(gas) / methanol / 1 h / -22 °C 2: 17 percent / methanol / 0.5 h 3: 40 percent / concd. HCl, 50percent aq. hypophosphorus acid, NaNO2 / H2O / 1 h / 0 °C 4: 87 percent / NH3(gas) / methanol / 24 h / 22 °C View Scheme

1: 71.3 percent / dimethylsulfoxide / 20 h / Ambient temperature 2: 62.2 percent / 0.25 h / 135 °C / 0.1 Torr View Scheme