Structural and Quantitative Analyses of 4-Chloroaniline-Derived Oligomers

Abstract

The oxidation of 4-chloroaniline by a peroxidase resulted in eight oligomeric products. A reverse-phase high performance liquid chromatography (HPLC) method was developed so that substrate disappearance and the corresponding product formations could be quantitatively monitored. The product mixture was isolated from the aqueous reaction solution with solid-phase extraction and the extract components were separated by thin-layer chromatography (TLC). The individual TLC bands were extracted for mass spectrometric and proton nuclear magnetic resonance analyses. The product mixture was found to contain dimers, trimers, and tetramers with benzoquinone monoimine, benzopuinone di-mine, diaminobenzene, and azobenzene structures. Analytical methodologies were specific for the study of the oxidative transformation of 4-chloroaniline, but they should be applicable to other anilinederived oligomers.