Mapping out the reaction network of humin formation at the initial stage of fructose dehydration in water

The formation of humins hampers the large-scale production of 5-hydroxymethylfurfural(HMF)in biorefinery.Here,a detailed reaction network of humin formation at the initial stage of fructose-to-HMF dehydration in water is delineated by combined experimental,spectroscopic,and theoretical studies.Three bimolecular reaction pathways to build up soluble humins are demonstrated.That is,the intermolecular etherification of β-furanose at room temperature initiates the C12 path,whereas the C-C cleavage of a-furanose at 130-150℃ leads to C11 path,and that of open-chain fructose at 180℃ to C11' path.The successive intramolecular dehydrations and condensations of the as-formed bimolecular intermediates lead to three types of soluble humins.We show that the C12 path could be restrained by using HCl or AlCl_(3) catalyst,and both the C12 and C110 paths could be effectively inhibited by adding THF as a co-solvent or accelerating heating rate via microwave heating.

构建多维教学平台开展以学生为中心的绿色化学线上教学

四川大学绿色化学课程为全英文课程,新型冠状病毒肺炎(COVID-19)疫情期间,教学团队结合课程特征,构建了基于超星泛雅平台、QQ群、QQ群课堂、问卷星、B站、微信公众号的多维教学平台,从课前准备、课堂教学、课后检测和反思这三大环节对教学全过程进行优化,坚持以学生为中心,结合基于任务驱动的翻转课堂形式,开展了疫情期间的线上教学。实践结果表明,任务驱动的协作学习模式充分调动了学生的学习积极性,使学生的语言运用能力、专业素养、以及分析评价和解决问题等高阶思维能力均得到了充分训练。