Bierol, tetramer lignin model compound was synthesized from guaicylglycerol-ß-guaiacyl ether (Erol) by oxidative dimerization using Horseradish peroxidase (HRP) / H2O2 biomimetic oxidation system. Starting material Erol, a (β-O-4) type lignin model compound was synthesized in 80% overall yield in six steps from acetovanillone.
The reactions progresses were associated with thin layer chromatography (TLC) and the purity of each product was obtained by High Performance Liquid Chromatography (HPLC) analysis techniques. The 1H and 13C NMR characteristics of the resulting products were studied using 1H and 13C NMR spectra as well as 2D NMR, in particular (Heteronuclear Single Quantum Coherence) HSQC.
The objectives of this series of investigation was three-fold: (a) to synthesize dimeric lignin model compounds (ß-O-4), (b) to synthesize tetrameric lignin model compounds, (c) to study 1H and 13C NMR and 2D NMR spectroscopic characteristics of compounds.
The research conducted in this project was successful as the model compounds were synthesized and characterized. Accordingly, the results were discussed in terms of signal assignments that confirmed the molecules structures. The general knowledge of lignin, e.g. chemical structure of lignin, the synthetic methods for synthesizing (ß-O-4) type model compounds, the different methods for lignin oxidative degradation and the various methods of lignin analysis were reviewed.
