Reaction CXVII.—-Action of Nitrous Fumes on certain Organic Compounds

The nitrous acid in the reaction is oxidised to nitric acid, and this produces nitration. 

When the p-position is occupied, the yield is almost theoretical, e.g., 

100 gms. salicylic acid and 130 gms. sodium nitrite are mixed with 150 c.cs. water and 1,200 c.cs. sulphuric acid (D. 1-52) are slowly added, the 

10 gms. aniline are dissolved in 100 c.cs. of 25% sulphuric acid and the solution cooled to 15°. 300 gms. sodium nitrite are dissolved in 100 c.cs. water and this solution added in two portions. When the first third is added cooling is applied, and the remainder of the nitrite is added without cooling. The mixture is then poured into a large evaporating basin on a water bath and boiling 50% sulphuric acid is cautiously added. When the action is over, the whole is steam distilled when the o-nitrophenol passes over. The p-compound is then extracted from the residue as in Preparation 232. 

Reaction CXVI1I. Action of Nitrous Acid on Aromatic Amines in presence of Cuprous Salts (Sandmeyer). 

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