酸性离子液体催化壳聚糖选择性转化为乙酰丙酸：与纤维素相比，引人注目的 NH 效应。
Selective conversion of chitosan to levulinic acid catalysed by acidic ionic liquid: Intriguing NH effect in comparison with cellulose.
机构信息
School of Chemistry, Dalian University of Technology, Dalian 116024, China.
School of Chemistry, Dalian University of Technology, Dalian 116024, China.
出版信息
Carbohydr Polym. 2018 Sep 1;195:267-274. doi: 10.1016/j.carbpol.2018.04.099. Epub 2018 Apr 27.
A highly selective route to produce levulinic acid (LA), one of the top twelve platform chemicals, from chitosan has been provided by catalysis of acidic ionic liquids (ILs). The effect of NH group on the conversion efficiency, IL recyclability and catalytic mechanism has been elucidated thoroughly in comparison with cellulose. Dilution effect was displayed significantly at lower chitosan intake, whereby the yield of LA was dramatically improved up to 64%. The relationship between IL structure and LA yield was established, disclosing that acidity of IL dictates the conversion efficiency of chitosan to LA predominantly. Moreover, methyl isobutyl ketone (MIBK) proved to be efficient extractant for the separation of LA product, and IL can be recycled without loss of activity by supplementing sulfuric acid. In addition, the chemical structures and morphologies of the solid residues were investigated by SEM and IR, indicating two-stage mechanism that chitosan first quaternizes and depolymerizes to glucosammonium salt, followed by transformation into LA through NH elimination.
一种高度选择性的方法，通过酸性离子液体（ILs）催化，从壳聚糖生产出 12 种顶级平台化学品之一的乙酰丙酸（LA）。与纤维素相比，详细阐明了 NH 基团对转化率、IL 可回收性和催化机制的影响。在较低的壳聚糖摄入下，显示出明显的稀释效应，从而使 LA 的产率大幅提高至 64%。建立了 IL 结构与 LA 产率之间的关系，揭示了 IL 的酸度主要决定了壳聚糖向 LA 的转化率。此外，甲基异丁基酮（MIBK）被证明是分离 LA 产物的有效萃取剂，并且通过补充硫酸可以在不损失活性的情况下回收 IL。此外，通过 SEM 和 IR 研究了固体残留物的化学结构和形态，表明壳聚糖首先季铵化和解聚为葡萄糖氨盐，然后通过 NH 消除转化为 LA，存在两阶段机制。
Zotero 插件