The catalytic ozonization of model lignin compounds in the presence of Fe(III) ions

The ozonization of several model lignin compounds (guaiacol, 2,6-dimethoxyphenol, phenol, and vanillin) was studied in acid media in the presence of iron(III) ions. It was found that Fe³⁺ did not influence the initial rate of the reactions between model phenols and ozone but accelerated the oxidation of intermediate ozonolysis products. The metal concentration dependences of the total ozone consumption and effective rate constants of catalytic reaction stages were determined. Data on reactions in the presence of oxalic acid as a competing chelate ligand showed that complex formation with Fe³⁺ was the principal factor that accelerated the ozonolysis of model phenols at the stage of the oxidation of carboxylic dibasic acids and C₂ aldehydes formed as intermediate products.