Nitration with nitrogen dioxide in the presence of sulphuric acid

NITRATION WITH NITROGEN DIOXIDE IN THE PRESENCE OF SULPHURIC ACID 

Pinck [88] studied the nitrating action of nitrogen dioxide in a sulphuric acid solution. According to this author, the nitrating action of the solution proceeds as follows, from each N204 molecule with the formation of one molecule of HN03 and one of nitrosylsulphuric acid  

When treating 1 mole of toluene with 1.05 mole of N204 in the presence of 1.6 moles of 95 % sulphuric acid at 50-55°C for 3 A hr, the yield of nitrotoluene obtained amounted to 87.5% of theory. 

Benzene activated with sulphuric acid would add on to N204 which, according to Battegay, has the structure of nitrosyl nitrate N02.0N0. An addition product was thought to be formed which, in the presence of an excess of sulphuric acid, would decompose to yield a nitro compound and nitrosylsulphuric acid. 

Titov and his co-workers [34] proposed the following mechanism of nitration of aromatic compounds with nitrogen dioxide in the presence of sulphuric acid  

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