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The chemical shifts of the ring protons of 1-X-2,4-dinitrobenzenes are changed with the addition of tetrabutylammonium bromide. In general, the chemical shift of proton 3 decreases with salt addition, that of proton 5 may increase or decrease, while that of proton 6 increases. Where X is an oxygen containing group, the changes are somewhat more pronounced.

Two synthetic routes to prepare a water-soluble stable free radical were investigated. The first product, sodium-2,4-dinitro-5-(4′-amino-2′,2′,6′,6′-tetramethylpiperidine-1-oxyl)benzene sulfonate, was water soluble but the sulfonate group was not readily replaceable with nucleophiles. The second synthetic route yielded N(4′-(2′,2′,6′,6′-tetramethylpiperidine-1-oxyl))-3,5-dinitro-4-sodium sulfonate benzamide, which was water soluble and its sulfonate group was readily replaced by nucleophiles.