NITRO DERIVATIVES OF TOLUENE 337Körner and Contardi [155]Körner and Contardi [156]
Brady and R. N. Williams [153]Körner and Contardi [158]
Brady and Taylor [136]OTHER BY-PRODUCTS IN THE NITRATION OF TOLUENE
Apart from the unsymmetrical isomers of trinitrotoluene, other by-products
are formed in the nitration process, owing to oxidation or decomposition processes.
Oxidation leads to the formation of di- and tri-nitrocresols, impurities fre-
quently met with in TNT. Nitrocresols are mainly formed during the nitration
of toluene to mononitrotoluene (Noelting and Forel [11]). If they have not been
removed from mononitrotoluene by washing with alkalis, they undergo either
further nitration to trinitrocresol, or oxidation to oxalic acid. Trinitrocresol may
be removed from TNT by mild alkali washing (e.g. with a NaHCO 3 or a sodium
sulphite solution).
During the trinitration the methyl group is oxidized to the carboxyl group.
The trinitrobenzoic acids behave in different ways in the course of hot washing
of crude TNT. Thus 2,4,6-trinitrobenzoic acid is readily decarboxylated and