sodium hydroxide 1.) reflux, 2 h, 2.) reflux, 45 min; Multistep reaction;

ammonium hydroxide; sodium dithionite T=20 - 50°C;

1: NaNO2, AcOH / H2O / 2 h / Ambient temperature 2: Na2S2O4, 25percent aq. NH4OH / 20 - 50 °C View Scheme

1: 1.) acetic anhydride, 2.) 10percent aq. NaOH / 1.) acetic anhydride, 70 deg C, 2 h, 2.) from 20 to 70 deg C, 1 h 2: NaNO2, AcOH / H2O / 2 h / Ambient temperature 3: Na2S2O4, 25percent aq. NH4OH / 20 - 50 °C View Scheme