Fuels and Energy Technology Institute, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia.
ChemSusChem. 2012 Aug;5(8):1427-34. doi: 10.1002/cssc.201100745. Epub 2012 Jun 22.
Acid treatments of xylose have been performed in a methanol/water mixture to investigate the reaction pathways of xylose during bio-oil esterification. Xylose was mainly converted into methyl xylosides with negligible humins formed below 130 °C. However, humins formation became significant with the dehydration of xylose to furfural and 2-(dimethoxymethyl)furan (DOF) at elevated temperatures. The conversion of xylose to methyl xylosides protected the C1 hydroxyl group of xylose, which stabilized xylose and suppressed the formation of sugar oligomers and polymerization reactions. In comparison, the conversion of furfural to DOF protected the carbonyl group of furfural. However, the protection did not remarkably suppress the polymerization of furfural at high temperatures because of the shift of the reaction equilibrium from DOF to furfural with a prolonged residence time. In addition, the acid treatment of furfural produced methyl levulinate in methanol and levulinic acid in water, which was catalyzed by formic acid.
已在甲醇/水混合物中对木糖进行酸处理，以研究生物油酯化过程中木糖的反应途径。在 130°C 以下，木糖主要转化为甲基木糖苷，几乎没有形成类黑精。然而，随着温度升高，木糖脱水生成糠醛和 2-（二甲氧基甲基）呋喃（DOF），类黑精的形成变得显著。木糖转化为甲基木糖苷保护了木糖的 C1 羟基，稳定了木糖，抑制了糖寡聚物的形成和聚合反应。相比之下，糠醛转化为 DOF 保护了糠醛的羰基。然而，由于反应平衡随着停留时间的延长从 DOF 向糠醛转移，这种保护并没有显著抑制糠醛在高温下的聚合。此外，糠醛的酸处理在甲醇中生成了甲基乙酰丙酸酯，在水中生成了乙酰丙酸，这是由甲酸催化的。
