Properties of 2-hydroxylaminoimidazoles

Reduction with ammonium chlroide and zinc dust is a satisfactory procedure for preparing N/sub 1/ substituted 2-hydroxylaminoimidazoles from the corresponding nitro compounds. In acidic solutions they are fairly stable and can be purified by high pressure liquid chromatography. In the solid state, in the absence of air and moisture, they are quite stable. 2-Hydroxylaminoimidazoles are readily oxidized to introso compounds under neutral conditions. However, in the presence of hydroxylamines, the nitroso derivatives undergo condensation reactions readily to form the azoxy derivatives. The formation of the azoxy compound provides a spectrophotometric assay for 2-hydroxylaminoimidazoles. In principle, the solution to be assayed is adjusted to pH 7 and then exposed to air. From the maximum increase in absorbance at 390 nm the concentration of hydroxylamine can be estimated. In the absence of air, in aqueous solution (> pH 7) 2-hydroxylaminoimidazoles are converted to a mixture of products, all resulting from the ''Bamberger-tye'' rearrangement product, 2-amino-4(5) hydroxyimidazole. These products are also electrophiles and can react with DNA bases. The substituent at the N/sub 1/ position affect the stability and reactivity of 2-hydroxylaminoimidazoles. The hydroxylamine derivative of SR 2508 is more stable that that of misonidazole and that from 2-nitro-imidazole (azomycin) is extremely unstable