Polyguaiacol: a Useful Model Polymer for Lignin Biodegradation Research

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Abstract
A polymer of ring-labeled [ 14 C] o -methoxyphenol ([ 14 C]guaiacol) was prepared by peroxidase-H 2 O 2 -catalyzed oxidation of the 14 C-labeled monomeric compound. The ring-labeled [ 14 C]polyguaiacol contained 67.71% carbon, 5.09% hydrogen, 27.49% oxygen, 25.44% methoxyl, and 8.60% phenolic hydroxyl. The polymer had an average molecular weight of between 5,000 and 15,000, as determined by gel chromatography. A schematic representation of the polymer, similar to previously published structures of polyguaiacols, was devised to meet these and other analytical parameters. The polymer is primarily composed of o-o and p-p -linked guaiacol moieties, with an occasional o-p -biphenyl link and some p -diphenoquinone structures. An approximate molecular formula is [C 49 O 14 H 31 ] n , where n 5.8. Its C 6 formula is C 6 H 2.3 O 0.3 carbonyl (OH) 0.7 (OCH 3 ) 1.0 . Polyguaiacol has many of the characteristics of a synthetic lignin. It is easier and less expensive to prepare than standard synthetic lignins (dehydrogenation polymers of coniferyl alcohol). It is degraded ([ 14 C]polyguaiacol → 14 CO 2 ) by the lignolytic system of the white-rot fungus Phanaerochaete chrysosporium. It is suggested that [ 14 C]polyguaiacol may be of value as a substrate for lignin biodegradation research.