Covalent binding of aniline to humic substances. 2. Nitrogen-15-NMR studies of nucleophilic addition reactions

Liquid-phase nitrogen-15 NMR spectrometry was used to observe the incorporation of nitrogen-15-labelled aniline into International Humic Substances Society (IHSS) soil fulvic and humic acid samples, an Iowa soil humic acid and the model compounds 4-methylcatechol and 1,4-benzoquinone. Aniline underwent nucleophilic addition reactions with the quinones and other carbonyl groups. Both oxidized and reduced forms of the Michael addition products of aniline with quinone groups occurred. Aniline became incorporated into anilide, anilinohydroquinone, anilinoquinone, imine and heterocyclic nitrogen. The anilide and anilinohydroquinone nitrogens were susceptible to chemical exchange by ammonia. There was a reduction in the incorporation of anilinohydroquinone hydrogen under anoxic conditions. There are 45 references.(see also preceding abstract).