Photocatalytic green synthesis of piperonal in aqueous TiO2 suspension

• We report the green synthesis of piperonal by the photocatalytic method.
• The photocatalytic efficiency of home prepared and commercial TiO2 powders was investigated.
• The best selectivity (ca. 35%) was obtained by using the home-prepared samples.

Piperonal (heliotropine or 3,4-methylenedioxybenzaldehyde) has been synthesized by oxidizing piperonyl alcohol in aqueous UV-irradiated TiO2 suspensions. This compound was identified by GC–MS chromatography, 1H NMR and melting point determination. The other products of the photoprocess were 1,3-bis(3,4-(methylenedioxy)benzyl) ether (found in traces) and CO2, derived from the parallel pathway of photo-mineralization. Commercial and home-prepared TiO2 samples have been tested and the best selectivity (ca. 35%) was obtained by using the home-prepared ones. The reported green process allows to obtain an added value product (piperonal), upon partial oxidation of a cheap reagent.

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