Laccase mediator systems (LMS) are well known for their ability to oxidize and modify even the non-phenolic units of lignin. Usually their primary oxidation target is in the benzylic position. We studied the effect of different types of laccase mediator systems on various lignin interunit linkages (β-5, β-β, β-O-4) and non-phenolic coniferyl alcohol end-groups. We used a set of mono- and dimeric lignin model compounds to identify the potential products by assessing the effect of the treatment using HPLC-, HPLC-MS- and NMR-techniques. In order to study the effects of the LMS-treatment on polymeric material, synthetic lignins (dehydrogenation polymer, DHP) were used. DHP’s consist of similar types of interunit linkages as lignins, however in different ratios. Especially, the so called lignin end units are much more abundant in these materials. In addition, for analysis, these polymers do not have to be exposed to harsh condition as in the case of isolation of natural lignin. It was found that particularly phenyl coumarans (β-5) and cinnamyl alcohol end groups showed high reactivity in the oxidation.

Effect of laccase mediator system oxidation on various lignin interunit linkages and end-groups

2019 Spring National Meeting

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