Evaluation of diazotized 4-amino-3,5-dinitrobenzoic acid (ADBA) as a new derivatizing reagent

Abstract

A preliminary evaluation of the reactivity of diazotized 4 amino-3,5-dinitrobenzoic acid (ADBA) towards selected aromatic compounds has been described. Successful diazo coupling of pharmaceuticals possessing aromatic rings of varying reactivities was achieved with the arenediazonium ion of ADBA at room (30°C) or elevated temperature 80oC) Z adducts formed in spot-test reactions were coloured for some compounds (e.g., cloxacillin and chloroxylenol), others show colour at elevated temperature of reaction (e.g., salicylic acid and aspirin), while others showed no detectable change in colour of reaction mixture, even at elevated temperature (e.g imidazole and tinidazole). The coloured product formed ai room temperature decomposed and the color discharged at elevated temperature in some cases (e.g., 0-naphthol). However, thin layer chromatographic analysis suggested that a more lipophilic derivative, relative to the original compound was formed for some of the compounds studied which did not show any detectable colour change in the spot test reactions. The diazotized ADBA is thus shown to be a reactive coupling reagent with which a suitable derivatization methodology could be developed for a wide range of pharmaceuticals in ultraviolet/visible spectrophotometry and high-performance liquid chromatographic (HPLC) analysis.