Aromatic aldehydes were oxidized to carboxylic acids in high yields and selectivity under mild conditions. The reactions were performed using aqueous sodium hypochlorite as oxidant in a liquid-liquid phase transfer catalytic system using quaternary ammonium salts as catalysts. The reaction was strongly pH-dependent, with maximum reaction rates at pH 9-11. Similarly, extraction of the hypochlorite ion was maximal at these pHs. The maxima are attributed to coextraction of hypochlorous acid together with the hypochlorite anion into the organic phase, the former significantly increasing the reaction rate.
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