两种β-O-4型木素高聚模型物的合成

Synthesis of two kinds of β-O-4 lignin model polymer

本文从4-羟基苯乙酮和4-羟基-3-甲氧基苯乙酮出发,经由CuBr2溴化、碱催化氧负离子亲核加成形成聚合物,再由NaBH4还原,合成了愈创木基型(G)和对羟苯基型(H)的木质素高聚模型物。高聚模型物经核磁共振氢谱和碳谱(1H-NMR、13C-NMR)、红外光谱(IR)、基质辅助激光解析串联飞行时间质谱(MALDI-TOF/TOF MS)和凝胶渗透色谱(GPC)表征,结果表明高聚物是含有β-O-4连接、无γ-C及γ羟基的直链聚合物,重复单元式量为136.16n+2。这类木质素模型物具有与分离木素类似的结构与性质,可溶于木质素常用溶剂,两种聚合物的重均分子量均在5000以上,与工业木质素分子量相近,其多分散度分别为1.26-1.76。该木质素高聚模型物的合成为进一步考察木素大分子在不同热化学环境下的热解特性提供了又一新的研究方法。

Lignin model polymer of guaiacyl（G）and hydroxyl-phenyl（H）was prepared through CuBr2 brominated,alkali catalyst oxygen anion nucleophilic addition reaction,using 4-hydroxyl acetophenone and 4-hydroxyl-3-methoxyl acetophenone as initiator,then reduced by NaBH4.The lignin model polymer were charactered by 1H-NMR and 13C-NMR,IR spectra（IR）,Matrix-Assisted Laser Desorption Ionization-Time of Flight Tandam Mass Spectrometer（MALDI-TOF-MS）and Gel Permeation Chromatography（GPC）.The results indicated that the polymer were linear chain polymer which contained β-O-4 linkages,but not Cγ and γ-OH.The molecular weight of repeat unit of polymer was 136.16 n＋2.The structure and properties of lignin model polymer were similar with that of separated lignin.It could be dissolved in conventional solvent of lignin.weight-average molar mass of polymers were above 5000 and more similar with that of technical lignin.The dispersion of lignin model polymer（H-type and G-type）,DPn were 1.26,1.76 respectively,The synthesis of lignin model polymer could provided a new experimental method for investigation pyrolysis and depolymerization of lignin under different thermochemical conditions.