Amines primary arylamines with nitrous

Primary aliphatic amines (RNH2) react with nitrous acid in the same way that primary arylamines (ArNH2) do, to form diazonium ions. But alkyldiazonium ions RN2 are much less stable than aryldiazonium ions ArN2 and readily lose nitrogen even at 0°C. Explain the difference. 

Salts of primary aromatic amines react with nitrous acid to produce diazonium salts. The reaction is usually performed by adding a cold solution of sodium nitrite to a cold solution of the arylamine in aqueous mineral acid. The end point of the reaction is conveniently determined by the detection of excess nitrous acid with potassium iodide-starch paper. Sulfamic acid has long been used both in industry and in the laboratory to remove excess nitrous acid. It has been found to react with the more active diazo compounds. In most cases, high temperatures are avoided to prevent the formation of phenols and the decomposition of the unstable nitrous acid. An excess of mineral acid is necessary to prevent coupling between the diazonium salt and unreacted amine (cf. method 494). If the amine salt is somewhat insoluble, a fine crystalline form, which is produced by rapid crystallization from a warm aqueous solution, may be employed. ... 

The most important reaction of amines with nitrous acid, by far, is the reaction of primary arylamines. We shall see why in Section 20.7. 

The most important reaction of amines with nitrous acid, by far, is the reaction of primary arylamines. We shall see why in Section 20.7. Primary arylamines react with nitrous add to give arenediazonium salts. Even though arenediazonium salts are unstable, they are still far more stable than aliphatic diazonium salts they do not decompose at an appreciable rate in solution when the temperature of the reaction mixture is kept below 5°C ... 

Aliphatic primary amines also give diazonium salts with nitrous acid. However, in this case the diazonium ion is not stabilized by resonance structures as in the case of arylamine, and decomposition to nitrogen and carbo-nium ions takes place. During the performance of the reaction the evolu-... 

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