Nucleophilic aromatic substitution 163NO 2O 2 NCl103Cl
NO 2NO 2
95N+ NFigure 4.392,4-Dinitrochlorobenzene (95) reacts with pyridine to form 2,4-dinitrophenylpyridinium
chloride (103),^229 a reactive intermediate which readily reacts with a variety of nucleophiles.^230
The reaction of (103) with hydrogen sulfide yields 2,2′,4,4′-tetranitrodiphenylsulfide
(104),^231 which on nitration–oxidation with fuming nitric acid, yields 2,2′,4,4′,6,6′-
hexanitrodiphenylsulfoxide (105).^212 The sulfide (104) is also formed from the reaction of
two equivalents of 2,4-dinitrochlorobenzene (95) with sodium thiosulfate or sodium disulfide
in aqueous ethanol.^212
SNO 2
105O 2 NO 2 NS OO
NO 2NO 2
104NO 2 NO 2NO 2NO 2NO 2Cl
NO 2NO 2
95H 2 Sfuming HNO 32Na 2 S 2 O 3 (aq)
refluxNO 2O 2 N Cl103NFigure 4.402,4-Dinitroiodobenzene is prepared by treating 2,4-dinitrochlorobenzene with sodium io-
dide in acetone.^232 2,4-Dinitrohalobenzenes undergo Ullmann coupling on treatment with
copper powder to yield 2,2′,4,4′-tetranitrobiphenyl.^233
4.8.1.4 Thermally insensitive explosives from halide displacement with
nitrogen nucleophiles
Analysis of the structure–properties relationships of many aromatic explosives has revealed
that the presence of amino functionality adjacent to nitro groups has a marked effect on
both thermal stability and sensitivity to impact.^234 The most striking example is seen during
the sequential introduction of amino groups into 1,3,5-trinitrobenzene.^235 Accordingly, both
1,3-diamino-2,4,6-trinitrobenzene (DATB) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)
are significantly more thermally stable and less sensitive to impact than 2,4,6-trinitroaniline
(picramide) and are designated as ‘heat resistant’ explosives. Such effects are attributed to
intramolecular hydrogen bonding interactions between adjacent amino and nitro groups which