Replacement of diazonium and diazo nitrogen

Aromatic amino groups can be replaced by other nitrogen-containing groups through the derived diazonium salts. 

The main interest of this reaction lies in the possibility of converting amines into nitro compounds. Many nitro compounds that cannot be prepared by direct nitration can be obtained easily in this way through neutral or weakly alkaline diazonium salt solutions in satisfactory and sometimes excellent yield. Success depends largely on choice of a suitable transfer agent for the nitro group.1171 Hodgson and Marsden172 state that diazonium hexanitrito-cobaltates are particularly suitable for production of the nitro compounds  

The amine (0.1 mole) is diazotized in hydrochloric or sulfuric acid solution by sodium nitrite (7 g), the volume of solution being kept as small as possible. The diazonium salt solution is neutralized with calcium carbonate and filtered, and trisodium hexanitritocobaltate (15 g) is stirred into the filtrate, whereupon the trisdiazonium salt usually separates as a solid. For conversion into the nitro compound this salt (10 g), finely powdered, is added in portions, at room temparature, with good stirring, to a solution of sodium nitrite (lOg) and copper sulfate (10 g) in water (60 ml) in which copper(i) oxide (4 g) is suspended. When evolution of nitrogen ceases the nitro compound is isolated either by extraction with a solvent, e.g., chloroform, or by basification of the solution and steam-distillation.172 

The following yields were obtained by this method 1-nitronaphthalene 68 %, 2-nitronaphtha-lene 60%, p-nitrotoluene 69 %, p-nitroanisole 68 %, and o-nitrotoluene 61 %.172 

A number of dinitronaphthalenes have also been prepared similarly, but in less good yields.1172 

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