Abstract
Although lignin is the most abundant natural phenolic polymer, its phenol activity is extremely low. Because most phenolic hydroxyl groups of lignin precursors were etherified in the biosynthetic process. In the present work, successive cleavage of ether linkages of lignin was carried out
Lignophenols synthesized from native lignins through the phase-separation process were depolymerized under the mild alkaline condition. The guaiacyl and syringyl aryl coumaran dimmers were isolated from the hardwood lignocresol treated with 1.0 N NaOH in 21% and 7.4%, respectively. Demethylation of methoxyl group in the syringyl aryl coumaran dimmer was carried out using boron tribromide. The pyrogallol type and 3-methoxy catechol type aryl coumaran were detected with LC/MS analysis. The pattern of demethylation of methoxyl group in the syringyl aryl coumaran dimmer was controlled by lewis acid treatment condition.
