Electrophilic aromatic substitution. Part 34. Nitration of 1-chloro-4-nitro-benzene, 1,3-dichloro-2-nitrobenzene, 1,3-dinitrobenzene, 1-chloro-2,4-dinitro-benzene, and 2-chloro-1,3-dinitrobenzene in sulphuric acid and oleum

Abstract

Yields of the expected nitro products from 1-chloro-4-nitrobenzene and 1,3-dichloro-2-nitrobenzene nitrated at 25 °C in sulphuric acid or oleum containing 1 mol dm^–3 nitric acid were quantitative. The rate profile for nitration of 1,3-dichloro-2-nitrobenzene is normal, but sulphonation is a competing process when the concentration of nitric acid is low. Kinetics of nitration of 1,3-dinitrobenzene at 150 °C are reported; yields of 1,3,5-trinitrobenzene, the only detected aromatic product, are low. The title chlorodinitrobenzenes each give, on nitration at 130 °C, a dichlorodinitrobenzene as well as a chlorotrinitrobenzene. The kinetics and yields of the two products from 1-chloro-2,4-dinitrobenzene under a variety of conditions are reported and discussed in relation to a previously proposed mechanism.