Effect of Water Content on Conversion of d-Cellobiose into 5-Hydroxymethyl-2-furaldehyde in a Dimethyl Sulfoxide鈥揥ater Mixture

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• 作者：Hiroshi Kimura ; Ken Yoshida ; Yasuhiro Uosaki ; Masaru Nakahara
• 刊名：Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：October 31, 2013
• 年：2013
• 卷：117
• 期：43
• 页码：10987-10996
• 全文大小：448K
• 年卷期：v.117,no.43(October 31, 2013)
• ISSN：1520-5215

文摘

Noncatalytic conversion of d-cellobiose (at 0.5 M) into 5-hydroxymethyl-2-furaldehyde (5-HMF), a platform chemical for fuels and synthetic materials, was analyzed at 120鈥?00 掳C over a wide range of water mole fraction, x_w = 0.007鈥? in a binary dimethyl sulfoxide (DMSO)鈥搘ater mixture by means of the in situ ¹³C NMR spectroscopy. Effects of the water content were revealed as follows: (i) The tautomerization of the anomeric residue of d-cellobiose from d-glucose to d-fructose type was not initially observed at a lower water content, in contrast to the significant tautomerization into the d-fructose type in a higher water content and pure water. (ii) The lower the water content, the faster the glycosidic-bond cleavage by hydrolysis, because of the high reactivity of solitary water molecules with the large partial charges more naked as in supercritical water clusters due to the isolation by the organic solvent DMSO. (iii) The amount of d-fructose as the intermediate product was larger at the higher x_w; despite the increase of d-fructose, the production of 5-HMF from d-fructose was slowed down. (iv) A high 5-HMF yield of 71% was reached at x_w = 0.20鈥?.30 that was 6鈥?0 times the initial d-cellobiose concentration. The best yield of 5-HMF was attained in the low x_w region when the polymerization paths into NMR-undetectable species via 5-HMF and anhydromonosaccharides were effectively suppressed. This study provides a new framework to design optimal, noncatalytic reaction process to produce 5-HMF from cellulosic biomass by tuning the water content as well as the temperature and the reaction time.