Liu Xiaofang, Yang Wenjia, Zhang Qiuyun, Li Can, Wu Hongguo
Guizhou Provincial Key Laboratory for Rare Animal and Economic Insects of the Mountainous Region, College of Biology and Environmental Engineering, Guiyang University, Guiyang, China.
School of Chemistry and Chemical Engineering, Anshun University, Anshun, China.
Front Chem. 2020 Oct 15;8:794. doi: 10.3389/fchem.2020.00794. eCollection 2020.
Biomass is a potential non-food, carbon-neutral, and abundant resource, which can be used as an alternative to fossil fuels during the sustainable preparation of various platform chemicals. Alkyl levulinates (ALs) have found widespread application as flavorings, plasticizing agents, and fuel additives, as well as synthetic precursors to various building blocks. Several processes have been investigated to transform biomass and its derivatives into ALs, which mainly include: (i) direct esterification of levulinic acid (LA) with alkyl alcohols and (ii) alcoholysis reactions of renewable biomass feedstocks and their derivatives, including furfuryl alcohol (FAL), chloromethyl furfural (CMF), and saccharides. This review focuses on illustrating the effects of the biomass pretreatment step, catalyst texture, possible mechanisms, acidities, and intermediates on the synthesis of ALs from sustainable resources covering a wide range of intermediates, including diethyl ether (DEE), 4,5,5-triethoxypentan-2-one (TEP), ethoxymethylfuran (EMF), ethyl-D-fructofuranoside (EDFF), and ethyl-D-glucopyranoside (EDGP).
生物质是一种潜在的非粮食、碳中性且丰富的资源，在各种平台化学品的可持续制备过程中可用作化石燃料的替代品。烷基乙酰丙酸酯（ALs）作为调味剂、增塑剂、燃料添加剂以及各种结构单元的合成前体已得到广泛应用。人们已经研究了几种将生物质及其衍生物转化为ALs的工艺，主要包括：（i）乙酰丙酸（LA）与烷基醇的直接酯化反应，以及（ii）可再生生物质原料及其衍生物（包括糠醇（FAL）、氯甲基糠醛（CMF）和糖类）的醇解反应。本综述重点阐述了生物质预处理步骤、催化剂结构、可能的机理、酸度以及中间体对从可持续资源合成ALs的影响，这些可持续资源涵盖了广泛的中间体，包括二乙醚（DEE）、4,5,5-三乙氧基戊-2-酮（TEP）、乙氧基甲基呋喃（EMF）、乙基-D-果糖呋喃糖苷（EDFF）和乙基-D-葡萄糖吡喃糖苷（EDGP）。
