Title:
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The synthesis and transformation of novel lignin model oligomers
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Lignin is a complex, interlinked, non-repeating, heterogeneous bio-polymer found in wood which
consists of phenylpropane subunits. The phenolic monomers of lignin are linked via various ether and
carbon-carbon bonds. It is the second most abundant biopolymer after cellulose, accounting for 15-30
% of biomass and it has the potential to be a renewable source of small aromatic feedstock molecules.
The synthesis of lignin model compounds plays an important role in both the elucidation of lignin's
structure and in modelling the conditions required for the production of valuable feedstock molecules
from lignin depolymerisation.
The aim of the research presented in this thesis has been to provide an efficient route to multi-gram
quantities of lignin model compounds which are more representative of lignin than the low molecular
weight models typically employed in previously published work. The syntheses of several hexameric lignin models as well as an octamer, all of which contain three of the most common linkages in the
native polymer have been carried out. The synthetic methodology used improves upon existing
methods of preparing higher molecular weight lignin models in both overall yield and efficiency as
well as practically on a multi-gram scale. Several of these compounds were then subjected to
published procedures aimed at the transformation of lignin and model compounds into added value
fine chemical intermediates. Extensive analysis of the major products was performed leading to some
preliminary mechanistic insights into lignin oxidative and reductive depolymerisation chemistry.
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