Transformation pathways of 2,4,6-trinitrobenzoic acid in the aqueous-phase hydrogenation over Pd/C catalyst

• Hydrogenation of 2,4,6-trinitrobenzoic acid over Pd/Sibunit catalyst.
• Identification of numerous reaction intermediates using NMR spectroscopy.
• Scheme of transformations of substrate and intermediates in an aqueous medium.

Results of the catalytic hydrogenation of 2,4,6-trinitrobenzoic acid (TNBA) in the presence of 1% Pd/C catalyst with analysis of the reaction products at the steps corresponding to the consumption of 1, 3, 5, 6, 8 and 9 mols of hydrogen per mol of TNBA are presented. Numerous reaction intermediates were identified using the 1H and 13C NMR spectroscopy; the reaction mixture composition was assessed quantitatively at different steps of the hydrogenation. The data obtained were used to propose a scheme of TNBA transformations over the Pd/C catalyst in the aqueous-phase reaction conditions. The data on the component composition at different steps of TNBA hydrogenation are important to understand the process chemistry, to explore the possibility of selective formation of different types of intermediate nitroamino compounds, and to synthesize high-performance catalysts for the hydrogenation of aromatic polynitro compounds.

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