COMPARATIVE STUDY OF OZONATION OF TWO LIGNIN MODEL COMPOUNDS : CONIFERYL ALCOHOL AND FERULIC ACID IDENTIFICATION OF SOME BY-PRODUCTS

摘要

The objective of our study was to compare the reactivity of coniferyl alcohol and ferulic acid with ozone at acidic pH in term of ozone demand and by-products formation. Both structures exert an ozone demand of about two moles of ozone per mole of initial compound. Similar ozonation by-products were identified using gas chromatography/ mass spectrometry analysis. Using a low ozone dose (below the ozone demand), byproducts were principally aromatic structures with vanillin, 3,4-dihydroxy-5-methoxybenzaldehyde and vanillic acid as the main compounds. Applying an higher ozone dose (above the ozone demand), furanic structures were produced. The production of such structures was explain by first a 1-3 dipolar cycloaddition on the ethylenic bond followed by the attack of the aromatic ring to produce a muconic acid derivative. Coniferyl alcohol was found to be a strong precursor of vanillin and vanilic acid than ferulic acid.