Intro:This is an electrophilic substitution reaction (nitration)Nitric acid and sulphuric acid are used to create the electrophile (NO2+)The electrophile then substitutes itself with a H atom on the benzene ring
Formation of the electrophile:Nitric acid is weaker than sulphuric acid, therefore it acts as a base in the reactionH2SO4 + HNO3 = H2NO3+ + HSO4-H2NO3+ = H2O + NO2+NO2+ is the electrophile - it attacks the delocalised ring of electrons in benzene[demonstrate mechanism of electrophile formation]
The Reaction:C6H6 + H2SO4 + HNO3 = C6H5NO2 + H2O + H2SO4The sulphuric acid is a catalyst, therefore it is re-formed[demonstrate mechanism of main reaction]