Piassava Fibers (Attalea funifera): NMR Spectroscopy of their Lignin

Abstract

Lignin of piassava (Attalea funifera) was analyzed by 1H- and 13C-NMR spectroscopy. The HGS-nature of this lignin was confirmed but p-coumarate units are also present in the lignin. Methoxyl and phenolic hydroxyl contents per phenylpropanic unit were determined by 1H-NMR spectroscopy to be 0.57 and 0.68, respectively and are in agreement with wet chemistry methods. A small extent of lignin condensation (35%) was explained by the high content of cinnamyl alcohol structures, evidenced by 13C-NMR-DEPT. An extended C9-formula for the piassava lignin was established to be C9.00 Har2.25 Hal3.73 O0.89 (OH)ph0.69 (OH)al0.86 (OCH3)0.57.