1: With sulfuric acid; sodium nitrite T=0°C; 2: With phosphoric acid; copper(II) oxide in water T=0 - 40°C; 2 h; 3: With sodium hydroxide in water pH=~ 9;
1: With phosphoric acid; nitric acid; sodium nitrite in water T=0°C; 0.5 h; 2: With hydrogen bromide; copper(I) bromide in water T=0°C; 1 h; 3: With sodium hydroxide in water pH=~ 4;
