Mechanistic role of protonated polar additives in ethanol for selective transformation of biomass-related compounds
Mechanistic role of protonated polar additives in ethanol for selective transformation of biomass-related compounds
复制标题
乙醇中质子化极性添加剂对生物质相关化合物选择性转化的机制作用
DOI：
10.1016/j.apcatb.2019.118509
复制
发表时间：
2020-05-05
影响因子：
22.1
通讯作者：
Smith, Richard Lee, Jr.
中科院分区：
文献类型：
--
作者：
Guo, Haixin;Duereh, Alif;Smith, Richard Lee, Jr.
我们报告的综合实验，光谱和理论研究的酸催化脱水-醚化的果糖在乙醇中的极性溶剂添加剂和产品选择性的机械作用的理解。在本文中，我们表明，在乙醇中用常见固体酸催化剂质子化的极性溶剂添加剂（例如四氢呋喃、丙酮、乙腈、γ-戊内酯、二甲基亚砜）可以将生物质相关化合物转化为所需的脱水或醚化产物。在具有DMSO添加剂的乙醇中的果糖被选择性地转化为5-羟甲基糠醛，由于根据其极性的优先DMSO质子化，5-乙氧基甲基糠醛的形成可忽略不计。光谱方法和密度泛函理论表明，具有比乙醇更高的极性的添加剂容易质子化，并作为关键的催化质子化物种和作为反应中间体的关键稳定物种。了解质子化极性添加剂在反应体系中的作用机制，可以使人们在酸催化脱水-醚化方案中定制选择性，并为生物质资源开发可持续的化学。
We report on a combined experimental, spectroscopic and theoretical study of acid catalysed dehydration-etherification of fructose in ethanol for understanding the mechanistic role of polar solvent additives and product selectivity. Herein, we show that polar solvent additives (e.g. tetrahydrofuran, acetone, acetonitrile, gamma-valerolactone, dimethyl sulfoxide) protonated with a common solid acid catalyst in ethanol allow transformation of biomass-related compounds into desired dehydration or etherification products. Fructose in ethanol with DMSO additive is selectively transformed into 5-hydroxymethylfurfural with negligible formation of 5-ethoxymethylfurfural due to preferential DMSO protonation according to its polarity. Spectroscopic methods and density functional theory show that additives having higher polarity than ethanol are readily protonated and act as the key catalytic protonation species and as the key stabilization species for reaction intermediates. Understanding the mechanism of protonated polar additives in reaction systems allows one to tailor selectivity in acid-catalyzed dehydration-etherification schemes and to develop sustainable chemistry for biomass resources.