Nitration of alkylbenzenes catalysed by mercury(II), thallium(III) and lead(IV)

Abstract

The nitration of alkylbenzenes, catalysed by mercury(II), has been studied in a range of solvents. Using toluene as a model, catalysis, accompanied by a corresponding change in isomer ratio, is observed in a nitric acidacetic acid system and also when dilute nitric acid is employed as the solvent. The results are consistent with a mercuration–nitrosodemercuration sequence occurring on the aromatic ring. Under more forcing nitrating conditions catalysis is not observed. With other alkylbenzenes there is little evidence of catalysis though a complication, with compounds possessing benzylic hydrogen atoms, is that reaction occurs on the side chain. This may remove nitrosating species from the system. Thallium(III) and lead(IV), which are isoelectronic with mercury(II), catalyse nitration without affecting the isomer distribution.