6-dinitrobenzene (TCDN B) has been treated with a number of bidentate nucleophiles, all of which contained at least one amino or methylamino group. Diamines of the type H,N(CH,)nNHR (R = H or Me, n = 2, 3, or 5 ) , reacted via the primary amino group displacing a nitro group from TCDNB. The resulting products were inert to further reaction, i.e. cyclisation or further nucleophilic substitution. Both 2-hydroxyethylamine and ethyl glycinate behaved similarly, although ethyl diazoacetate was a by-product in the latter reaction.The reaction of TCDNB with hydrazine hydrate was very sensitive to the conditions employed, i.e. rapid addition of excess of reagent (2.2 : 1 molar ratio) gave 3,4,5,6-tetrachloro-o-phenylenediamine (reduction had occured). Slow addition of an equimolar amount yielded 2,3,4,5-tetrachloro-6nitrophenylhydrazine, i.e. nucleophilic substitution. N,N'-Dimethylethylenediamine and 2hydroxy-Nmethylethylamine reacted with TCDN B to give cyclised products, i.e. both nucleophilic centres reacted. The course of these reactions was investigated. In contrast 2-acetoxyethylamine, glycine, urea, 2,2'iminodiethanol and butane-1 ,I ,4,4-tetra-amine were all unreactive towards TCDN B.