Nitrating systems a. mineral acids

Nitration can be effected under a wide variety of conditions, as already indicated. The characteristics and kinetics exhibited by the reactions depend on the reagents used, but, as the mechanisms have been elucidated, the surprising fact has emerged that the nitronium ion is preeminently effective as the electrophilic species. The evidence for the operation of other electrophiles will be discussed, but it can be said that the supremacy of one electrophile is uncharacteristic of electrophilic substitutions, and bestows on nitration great utility as a model reaction. 

Euler first suggested that the nitronium ion was the active species, but proof of this did not come for many years. Investigations of the mechanisms have been chiefly concerned with the physical examination of the media used, and with the kinetics of the reactions. 

---