Green Synthesis and Fractionation of Cellulose Acetate by Controlling the Reactivity of Polysaccharides in Sugarcane Bagasse
Green Synthesis and Fractionation of Cellulose Acetate by Controlling the Reactivity of Polysaccharides in Sugarcane Bagasse
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控制甘蔗渣中多糖的反应活性进行醋酸纤维素的绿色合成与分馏
DOI：
10.1021/acssuschemeng.0c01639
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发表时间：
2020
影响因子：
8.4
通讯作者：
Takahashi Kenji
中科院分区：
文献类型：
--
作者：
Suzuki Shiori;Yada Risa;Hamano Yosuke;Wada Naoki;Takahashi Kenji
开发了一种绿色合成工艺，可以直接从甘蔗渣中制取纤维素醋酸酯(CA)，而不需要任何预处理或腐蚀性试剂，如强酸、强碱或卤化化学品。这种方法的关键是在温和的条件下控制蔗渣中纤维素和木聚糖基半纤维素的反应活性，使它们在丙酮中的溶解度不同。以乙酸异丙烯为乙酰基供体，1-乙基-3-甲基咪唑为溶剂和催化剂，在50℃下对蔗渣进行了均相酯交换反应。通过控制反应温度，将纤维素的取代度调节到2.5-2.8，以保持其在丙酮中的溶解性，同时抑制半纤维素的乙酰化，以防止其在丙酮中溶解。在随后的分馏过程中，富含半纤维素的成分首先在丙酮中沉淀，然后通过过滤去除。随后，通过使用甲醇的固液分离，将滤液分离成富含木质素和纤维素的级分。通过红外光谱和核磁共振氢谱分析，确定目标化合物CA为丙酮可溶部分和甲醇不溶部分，纯度高(∼90%)。
A green synthetic protocol was developed to prepare cellulose acetate (CA) directly from sugarcane bagasse without using any pretreatments or corrosive reagents, such as strong acids, bases, or halogenated chemicals. The key in this method is to control the reactivities of cellulose and xylan-based hemicellulose in bagasse under mild conditions, making their solubilities in acetone different. Homogeneous transesterification was performed for bagasse at 50 °C using isopropenyl acetate as an acetyl donor and 1-ethyl-3-methylimidazolium acetate as a solvent and catalyst. By controlling the reaction temperature, the degree of substitution for cellulose was adjusted to 2.5–2.8 to maintain solubility in acetone, while the acetylation of hemicellulose was suppressed to prevent its dissolution in acetone. In the subsequent fractionation process, the hemicellulose-rich component was first precipitated in acetone and removed by filtration. The filtrate was subsequently separated into lignin- and cellulose-rich fractions by solid–liquid separation using methanol. Then, CA as the target compound was collected as the acetone-soluble and methanol-insoluble fraction, with a sufficiently high purity (∼90%), according to FT-IR and1H NMR analyses.