Lignocellulose Conversion via Catalytic Transformations Yields Methoxyterephthalic Acid Directly from Sawdust

Poly(ethylene terephthalate)
polyester represents the most common
class of thermoplastic polymers widely used in the textile, bottling,
and packaging industries. Terephthalic acid and ethylene glycol, both
of petrochemical origin, are polymerized to yield the polyester. However,
an earlier report suggests that polymerization of methoxyterephthalic
acid with ethylene glycol provides a methoxy-polyester with similar
properties. Currently, there are no established biobased synthetic
routes toward the methoxyterephthalic acid monomer. Here, we show
a viable route to the dicarboxylic acid from various tree species
involving three catalytic steps. We demonstrate that sawdust can be
converted to valuable aryl nitrile intermediates through hydrogenolysis,
followed by an efficient fluorosulfation–catalytic cyanation
sequence (>90%) and then converted to methoxyterephthalic acid
by
hydrolysis and oxidation. A preliminary polymerization result indicates
a methoxy-polyester with acceptable thermal properties.