1.1: sodium chloride / water; dimethyl sulfoxide / 8 h / 145 - 155 °C 2.1: hydrazine hydrate / ethanol / 4 h / Reflux 3.1: hydrogenchloride; sodium nitrite / water / 1.5 h / 55 - 60 °C 3.2: pH 12 4.1: water; hydrogen bromide / 5 h / 100 - 110 °C View Scheme