Structural Analysis of Acid-Catalyzed Organosolv Lignins by a Combination of Nucleus Exchange Reaction and Nitrobenzene Oxidation

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Aspen (Populus tremuloides) chips were treated with methanol: water (70 : 30 by volume), at 165℃for 2.5hours, with catalysts (NaHSO4, H2SO4 and H3PO4), using a liquor-to-wood ratio of 4:1. Thestructures of the resulting organosolv lignins were analyzed by the combination of nucleus exchangereaction and nitrobenzene oxidation. Above the liquor pH 3.2, the compositions of dissolved lignins weresimilar to that of original lignin and the condensation reaction did not occur extensively. However, withdecreasing liquor pH (below pH 3.0), the condensation occurred dramatically, forming diphenylmethanetype structures. The dissolved lignins were rich in guaiacyl units which were mainly of type Gb.オルガノソルブリグニンの有効利用に関する基礎的知見を得るため，Aspenチップがメタノール－水系で処理され，溶出リグニンの構造が蒸解液pHとの関連で論議された。pH3.2以上では，溶出リグニンの組織はオリジナルリグニンと頼似していたが，pHの低下とともに縮合反応が開始され，Cα－アリール縮合構造が形成された。低pHで流出するリグニンは，ダアイアイアシル単位にリッチであった。
Faculty of Bioresources, Mie Universityの論文
1991-03-28