Abstract
As part of the systematic studies on imidazole derivatives as chelating agents, four azoimidazoles having an ortho-hydroxy group, a dimethylamino group, or both groups were prepared from 4(5)-amino-5(4)-methylimidazole as a diazo component and 2-naphthol, p-methoxyphenol, N, N-dimethylaniline, and N, N-dimethyl-m-aminophenol as coupling components : 1-[4(5)-methyl-5(4)-imidazolylazo]-2-naphthol ; 2-[4(5)-methyl-5(4)-imidazolylazo]-4-methoxyphenol ; 4(5)-methyl-5(4)-(p-dimethylaminophenylazo) imidazole ; 3-dimethylamino-6-[4(5)-methyl-5(4)-imidazolylazo] phenol. The reactions of the azo derivatives with various metal ions were studied by spot tests in acid, neutral, and alkaline solutions. All the azo derivatives react with metal ions, such as Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Pd(II) and Pb(II), to give intensely colored chelates which are usually extracted into chloroform or iso-amyl alcohol. These results indicate that the azoimidazoles can be used as metallochromic indicators or as extractants for determinations of metal ions by chelatometric titrations or by solvent extractions.
