Abstract. Goethite, hematite and intermediate products of goetite thermal decomposition were studied by IR and Raman spectroscopy to identify these products used as catalysts of some chemical reactions. The presence of a small number of OH-groups in the products of the decomposition up to 900-1000 ~ C was supposed to hinder the formation of perfect hematite structure. The hypothesis concerning C6v space group of protohematite indistinguishable from D36a space group of hematite by X-Ray diffraction was suggested. This hypothesis explains both the additional lines in IR and Raman spectra compared to hematite spectra and the same position of peaks in X-Ray diffraction picture.

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The present study considered the influence of various factors on the catalytic activity of systems based on a combination of tetrakis(oxodiperoxotungsto)phosphate(3-) with quater nary ammonium cations, for example, with methyltri n octylammonium [Me(n C 8 H 17 ) 3 N] + . The catalysts were tested in oxidation of cycloolefins (cyclohexene and cyclooctene), alcohols (octan 1 ol and phenylmethanol), and unsaturated fatty acids (cis 9 octadecenoic and 12 hydroxy 9Z octadecenoic acids) with a 30% hydrogen peroxide solution. These reactions proceed under mild conditions (atmospheric pressure, 80-90 °C) to give carboxylic acids. The catalytic systems were characterized by vibrational (IR and Raman) spectroscopy. The state of the systems formed from various precursors, viz., polyoxometallates and phase transfer cata lysts, was studied. It was demonstrated for the first time that the structure formation of peroxo complexes depends on the nature of the halide anion of the quaternary ammonium salt used. The melting points of individual catalytic complexes were determined. The optimal conditions for oxidation were found.

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