N-phosphonomethyl iminodiacetic acid N-oxide synthesis in the presence of bifunctional catalysts based on tungsten complexes

• Oxidation of N-phosphonomethyl iminodiacetic acid by H2O2 at 70 °C to its N-oxide in a two-phase system was investigated.

N-phosphonomethyl iminodiacetic acid (PMIDAA) was oxidized in a two phase liquid system by 32% hydrogen peroxide at 70 °С. Reaction was performed in the presence of tungsten oxo- and peroxo- complexes, containing N-hexadecylpyridinium or quaternary ammonium cation. Substrate conversion and N-oxide PMIDAA selectivity were found to depend on anions structure and quaternary nitrogen containing cation properties. The best results were obtained when PMIDAA was oxidized in the presence of N-hexadecylpyridinium tetra(oxodiperoxotungsto)phosphate, substrate conversion being 99%, and target product selectivity being 97%.

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