1: With iron; acetic acid T=80 - 90°C; 4 h; 2: With hydrogenchloride in 1,4-dioxane; water T=100°C; 3 h;

1: With hydrogenchloride; acetic acid; sodium nitrite in water T=-10 - -5°C; 1 h; 2: With sulfur dioxide; acetic acid; copper(l) chloride in water T=10 - 30°C; 0.5 h;