Systems formed from nitric acid and acetic anhydride

3 SYSTEMS FORMED FROM NITRIC ACID AND ACETIC ANHYDRIDE 

Vandoni and Viala examined the vapour pressures of mixtures of nitric acid in acetic anhydride, and concluded that from o to mole-fraction of nitric acid the solution consisted of acetyl nitrate, acetic acid and excess anhydride in equimolar proportions the solution consisted of acetyl nitrate and acetic acid, and on increasing the fraction of nitric acid, dinitrogen pentoxide is formed, with a concentration which increases with the concomitant decrease in the concentration of acetyl nitrate. 

A study of the Raman spectra of similar mixtures confirmed and extended these conclusions. The existence of the following two equilibria was postulated  

When acetic anhydride was in excess over nitric acid, acetyl nitrate and acetic acid were the only products. When the concentration of nitric acid was greater than 90 moles %, dinitrogen pentoxide, present as (N02+)(N0a ), was the major product and there were only small traces of acetyl nitrate. With lower concentrations of nitric acid the products were acetic acid, acetyl nitrate and dinitrogen pentoxide, the latter species being present as covalent molecules in this organic medium. A mixture of z moles of nitric acid and i mole of acetic anhydride has the same Raman spectrum as a solution of i mole of dinitrogen pentoxide in 2 moles of acetic acid. 

An investigation of the infra-red spectra of mixtures of nitric acid and acetic anhydride supports these conclusions. The concentration of nitronium ions, measured by the absorption band at 2380 cm, was 

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D Benzoyl nitrate and systems formed from nitric acid and acetic anhydride... 

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