Dinitration of chlorobenzene

Dinitrochlorobenzene can be manufactured by either dinitration of chlorobenzene in filming sulfuric acid or nitration ofy -nitrochlorobenzene with mixed acids. Further substitution on the aromatic ring is difficult because of the deactivating effect of the chlorine atom, but the chlorine is very reactive and is displaced even more readily than in the mononitrochlorobenzenes. 

Two activating electron-withdrawing groups are better than one and dinitration of chlorobenzene makes a very electrophilic aryl halide. Reaction with hydrazine gives a useful reagent. 

At the dinitration of chlorobenzene, the regioselection in the presence of zeolites was again improved in favour of the 2,4-dinitro isomer 2,4-12,6- = 48) [38]. In the presence of Faujasite-712, the nitration of o-chlorobenzene with N Oj gives a mixture of l-chloro-2,4-dinitro- and l-chloro-2,6-dinitrobenzenes in about 30 1 ratio [39]. Thus, the procedure for the regioselective dinitration of toluene and chlorobenzene described above, which involves the Kyodai nitration in polar organic solvent in the presence of zeolites, provides a new efficient route to 2,4-dinitro derivatives under nonacid conditions. The method is easy to carry out, environmentally benign, and economical. 

Mononitration. 3000 kg of chlorobenzene, boiling within a range of 0.8°C, is mixed with the spent acid from dinitration, containing 78% of H2S04. Then 1850 kg of a nitrating mixture of the compositions ... 

Nitration ofp chIoronitrobenzene to l-chloro-2,4>dinitrobenzene Nitration of chlorobenzene to chlorodinitrobenzene (Griesheim method) Mononitration Dinitration... 

The mixture of nitric acid and trifluoromethanesulfonic acid in CHjClj, CCI4, CF2CI2, CFQ3, and pentane solution is an excellent nitrating agent for benzene, toluene, m-xylene, chlorobenzene, nitrobenzene, and beozo-trifluoride (Table II). The reactions were carried out from —110 to 30 C. Mono- or dinitration of toluene can be controlled by specific reaction temperature. Mononitration of toluene is extremely rapid, the reaction being complete in one minute at -110X. The dinitration is complete in 30 min at 0 C. 

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