Hydroxylation of phenol by hydrogen peroxide catalyzed by heteropoly compounds in presence of glycerol as green solvent

• Glycerol was applied, for the first time, as green solvent in phenol oxidation.
• Influence of metal cations on selectivity of products in phenol oxidation has been explained.
• Iron salts of tungstophosphoric acid are active catalysts in oxidation of phenol to catechol and hydroquinone.
• Manganese and cobalt heteropoly salts are efficient catalysts in degradation of phenol to CO2.

Cobalt, manganese, and iron in cationic positions of the secondary structure of Mo- or W-Keggin type heteropolyanions were investigated in the liquid-phase oxidation of phenol in glycerol. Iron tungstophosphate series is the most active in this reaction, yielding catechol and hydroquinone. On the other hand, manganese and cobalt salts of heteropolyacids demonstrate higher catalytic activity in the degradation of phenol to CO2 in comparison with iron tungstophosphates. It is the first time that glycerol is used as alternative “green” solvent in phenol oxidation reaction.

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