Dinitrogen pentoxide, nitration with sulphuric acid

Solutions of dinitrogen pentoxide in nitric acid or sulphuric acid exhibit absorptions in the Raman spectrum at 1050 and 1400 cm with intensities proportional to the stoichiometric concentration of dinitrogen pentoxide, showing that in these media the ionization of dinitrogen pentoxide is complete. Concentrated solutions in water (mole fraction of NgOg > 0-5) show some ionization to nitrate and nitronium ion. Dinitrogen pentoxide is not ionized in solutions in carbon tetrachloride, chloroform or nitromethane. ... 

Nitration in the presence of strong acids or Lewis acids Solutions of dinitrogen pentoxide in sulphuric acid nitrate 1,3-dimethyl-benzene-4,6-disulphonic acid twice as fast as a solution of the same molar concentration of nitric acid. This is consistent with Raman spectroscopic and cryoscopic data, which establish the following ionisation ... 

With dinitrogen pentoxide pyridine gives 1-nitropyridinium nitrate sa and with nitronium fluoborate the corresponding fluoborate is formed Pyridine forms a 1 1 complex with phosphorus pentachloride Sc with sulphur dioxidei29 (43) and with sulphur trioxide o (44). The last is useful as a sulphonating agent (p. 80), and is formed from its components in carbon tetrachloride, from pyridine and fuming sulphuric acid, and from pyridine and chlorosulphonic acid. Its reactions are discussed later (p. 177). 

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