Nitration in aqueous solutions of mineral acids

4 NITRATION IN AQUEOUS SOLUTIONS OF MINERAL ACIDS 2.4.1 The state of nitric acid in aqueous sulphuric acid Nitric acid is completely converted into nitronium ions in concentrated sulphuric acid ( 2.3.1)  

Raman spectroscopy I c.i.so showed that the addition of up to io% of water does not affect the concentration of nitronium ions further dilution reduces the concentration of this species, which is not detectable in solutions containing 85 % sulphuric acid. The introduction of 

The ultraviolet spectra of solutions of potassium nitrate in various concentrations of sulphuric acid have been studied, and absorptions 

The vapour pressure of nitric acid, over solutions in sulphuric acid, reaches a maximum with 84-5 % sulphuric acid, the acidity corresponding to the formation of the monohydrate.  

Addition of water to solutions of nitric acid in 90% sulphuric acid reduces rates of nitration. Between 90% and 85% sulphuric acid the decrease in rate parallels the accompanying fall in the concentration of nitronium ions. This is good evidence for the operation of the nitronium ion as the nitrating agent, both in solutions more acidic than 90% and in weakly diluted solutions in which nitronium ion is still spectroscopically detectable. 

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