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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >In situ kinetic study on hydrothermal transformation of d -glucose into 5-hydroxymethylfurfural through d -fructose with ~(13)C NMR
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In situ kinetic study on hydrothermal transformation of d -glucose into 5-hydroxymethylfurfural through d -fructose with ~(13)C NMR

机译：用〜（13）C NMR通过d-果糖将d-葡萄糖水热转化为5-羟甲基糠醛的原位动力学研究

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摘要

Kinetics of hydrothermal reaction of d-glucose was investigated at 0.02 M over a temperature range of 120-160 °C by applying in situ 13C NMR spectroscopy. d-Glucose was found to be reversibly transformed first into d-fructose (intermediate) and successively into 5-hydroxymethylfurfural (5-HMF) through dehydration. The carbon mass balance has been kept within the detection limit, and no other reaction pathways are present. The hydrothermal reaction of d-glucose is thus understood as that of d-fructose in the sense that the d-glucose reaction proceeds only through d-fructose. All the isomers of d-glucose and d-fructose were detected by the in situ ~(13)C NMR in D_2O: they are the open chains and the pyranoses and furanoses of α- and β-types. The β-forms are the most stable due to the hydration. For both d-glucose and d-fructose, the isomers are in a rapid equilibrium for each monosaccharide, and they are treated collectively in the kinetic analysis of the slower hydrothermal reactions. The reactions are of the first order with respect to the concentrations of d-glucose and d-fructose, and d-glucose converts to 5-HMF on the order of hours. The kinetic parameters were determined by the in situ method.
机译：通过应用原位13 C NMR光谱研究了d-葡萄糖在0.02 M的水热反应动力学，温度范围为120-160°C。发现d-葡萄糖首先通过脱水可逆地转化为d-果糖（中间体），然后可逆地转化为5-羟甲基糠醛（5-HMF）。碳质量平衡已保持在检测限内，并且没有其他反应途径存在。因此，在d-葡萄糖反应仅通过d-果糖进行的意义上，将d-葡萄糖的水热反应理解为d-果糖的水热反应。 d-葡萄糖和d-果糖的所有异构体均通过D_2O中的〜（13）C NMR检测到：它们是α-和β-型的开链，吡喃糖和呋喃糖。由于水合作用，β形式最稳定。对于d-葡萄糖和d-果糖，异构体对每个单糖均处于快速平衡状态，并且在较慢的水热反应的动力学分析中将它们统一处理。关于d-葡萄糖和d-果糖的浓度，反应是一级的，并且d-葡萄糖在数小时的数量级上转化为5-HMF。动力学参数通过原位方法确定。

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