15N NMR investination of the covalent binding of reduced TNT amines to soil humic acid, model compounds, and lignocellulose

The five major reductive degradation products of TNT-4ADNT (4 amino 2 6 dinitrotoluene) 2ADNT (2 amino 4 6 dinitrotoluene) 24DANT(24 diamino 6 nitrotoluene) 26DANT (2 6 diamino 4 nitrotoluene) and TAT (2 4 6 triaminotol uene)-labeled with (15)N in the amine positions were reacted with the IHSS soil humic acid and analyzed by (15)N NMR spectrometry In the absence of catalysts all five amines underwent nucleophilic addition reactions with quinone and other carbonyl groups in the soil humic acid to form both heterocyclic and nonheterocyclic condensation products Imine formation via 12 addition of the amines to quinone groups in the soil humic acid was significant with the diamines and TAT but not the monciamines Horseradish peroxidase (HRP) catalyzed an increase in the incorporation of all five amines into the humic acid In the case of the diamines and TAT HRP also shifted the binding away from heterocyclic condensation product toward imine formation A comparison of quantitative liquid phase with solid state CP/MAS (15)N NMR indicated that the CP experiment underestimated imine and heterocyclic nitrogens in humic acid even with contact times optimal for observation of these nitrogens Covalent binding of the mono and diamines to 4 methylcatechol the HRP catalyzed condensation of 4ADNT and 24DANT to coniferyl alcohol and the binding of 24DANT to lignocellulose with and without birnessite were also examined.