Alcohol Effect and the Related Mechanism on Fructose Dehydration into 5-Hydroxymethylfurfural in the Deep Eutectic Solvent of [Emim]Cl/Alcohol

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• 作者：Jing Zhang ; Yuyan Xiao ; Yaohua Zhong ; Na Du ; Xirong Huang
• 刊名：ACS Sustainable Chemistry & Engineering
• 出版年：2016
• 出版时间：July 5, 2016
• 年：2016
• 卷：4
• 期：7
• 页码：3995-4002
• 全文大小：509K
• 年卷期：0
• ISSN：2168-0485

文摘

The ionic liquid [HNMP]Cl-catalyzed dehydration of fructose into 5-hydroxymethylfurfural (HMF) in deep eutectic solvents (formed by [Emim]Cl and different alcohols) was investigated. The experimental results indicated that the polarity of an alcohol and its stereostructure were major factors influencing fructose dehydration and that isopropanol was the optimum alcohol for the conversion system. Studies on the mechanism of the alcohol effect indicated that an alcohol could influence the formation of intermediates and their further transformation via the hydrogen bonds formed with [Emim]Cl and [HNMP]Cl. For the normal alcohols, the shorter the chain, the higher is the polarity and the stronger the ability to form the hydrogen bond; as a result, the alcohol with the shortest chain has the greatest negative effect on fructose dehydration. For the branched chain alcohols, the existence of steric hindrance led to their weaker ability to form the hydrogen bond with the ionic liquid so that their negative effects on the conversion were much smaller. The DES composed of equal moles of [Emim]Cl and isopropanol is the best one for the conversion of fructose into HMF catalyzed by [HNMP]Cl with an HMF yield of up to 89% after 3 h of reaction at 25 °C.