1: With hydrogenchloride; acetic acid; sodium nitrite in water; acetonitrile T=0°C; 0.75 h; 2: With sulfur dioxide in water; acetonitrile 2 h; 3: With sulfur dioxide; copper dichloride in water; acetonitrile T=0°C; 17 h;

sulfur dioxide; copper dichloride in water; acetic acid; acetonitrile T=-5 - 5°C;