- Catalysis and Stability Effect of Solvent Alcohol on the C6 Aldose Conversion toward Tetrose
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Conversions of biomass feedstock into various valuable chemicals are of great significance. As a typical route, retro-aldol condensation of monosaccharide greatly expands the variety of biomass-derived platform chemicals via a selective C?C splitting. Herein, we describe a solvent-catalysed strategy to high-selectively accumulate tetrose (four-carbon platform chemical) from C6 aldoses via the retro-aldol/aldol process. We find that alcohol solvents with Lewis acidity facilitate the C?C splitting process of hexose under the catalyst-free condition. The conversion is the fastest in methanol while it is the slowest in isopropanol. The product distribution is greatly influenced by the alcohols through shifting the equilibrium between tetrose and glycolaldehyde (GA). The addition of catalyst only accelerates the reaction rate, and does not change the product distribution. On the one hand, the acetalization of GA with methanol or ethanol shifts the equilibrium from tetrose toward GA, which results in a low yield of tetrose in methanol or ethanol solvent. On the other hand, tetrose can be well accumulated in isopropanol or n-butanol, and the yield of tetrose in isopropanol is higher than in n-butanol because tetrose can be well solvated and stabilized in it. This solvent-dependent reaction strategy provides a new possibility which contributes to the conversion of biomass feedback into valuable platform chemicals and accumulation of target products by utilizing the solvation effect.
- Hou, Wenrong,Yan, Yueer,Li, Gang,Zhan, Yulu,Feng, Lei,Zhang, Ruohong,Hua Li, Zhen,Zhang, Yahong,Tang, Yi
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p. 4182 - 4188
(2019/09/12)
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- Chemocatalytic Conversion of Cellulosic Biomass to Methyl Glycolate, Ethylene Glycol, and Ethanol
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Production of chemicals and fuels from renewable cellulosic biomass is important for the creation of a sustainable society, and it critically relies on the development of new and efficient transformation routes starting from cellulose. Here, a chemocatalytic conversion route from cellulosic biomass to methyl glycolate (MG), ethylene glycol (EG), and ethanol (EtOH) is reported. By using a tungsten-based catalyst, cellulose is converted into MG with a yield as high as 57.7 C % in a one-pot reaction in methanol at 240 °C and 1 MPa O2, and the obtained MG can be easily separated by distillation. Afterwards, it can be nearly quantitatively converted to EG at 200 °C and to EtOH at 280 °C with a selectivity of 50 % through hydrogenation over a Cu/SiO2 catalyst. By this approach, the fine chemical MG, the bulk chemical EG, and the fuel additive EtOH can all be efficiently produced from renewable cellulosic materials, thus providing a new pathway towards mitigating the dependence on fossil resources.
- Xu, Gang,Wang, Aiqin,Pang, Jifeng,Zhao, Xiaochen,Xu, Jinming,Lei, Nian,Wang, Jia,Zheng, Mingyuan,Yin, Jianzhong,Zhang, Tao
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p. 1390 - 1394
(2017/04/14)
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- Production of methyl levulinate from cellulose: Selectivity and mechanism study
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The alcoholysis of cellulose into methyl levulinate (ML) in methanol media was investigated in the presence of several kinds of acid catalyst. One of the synthesized solid niobium-based phosphate catalysts was found to be highly efficient for the generation of ML, reaching an ML yield as high as 56%, higher than the LA yield (52%) in aqueous solution with the same reaction conditions as those used in our previous study (Green Chem., 2014, 16, 3846-3853). More interestingly, in water, very strong Lewis acid promoted the formation of LA; but in methanol, Br?nsted acid enhanced the formation of ML. In-depth investigation showed that the mechanism and type of intermediates of cellulose alcoholysis in methanol were different from those in water and a high Br?nsted/Lewis acid ratio (known as B/L acid ratio) of solid catalysts is needed to prevent the generation of by-products, namely, methyl lactate and 1,1,2-trimethoxyethane. This new-proposed reaction mechanism affected by the B/L acid ratio was very helpful for the design of efficient catalysts.
- Ding, Daqian,Xi, Jinxu,Wang, Jianjian,Liu, Xiaohui,Lu, Guanzhong,Wang, Yanqin
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p. 4037 - 4044
(2015/07/15)
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- The synthesis of methyl lactate and other methyl oxygenates from cellulose
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Light oxygenates, such as methyl lactate (MLA), methyl levulinate (MLE), methyl formate (MFO), methyl acetate (MAC), dimethoxymethane (DMM), and methoxyacetaldehyde dimethyl acetal (MADA) were synthesized from cellulose in the presence of promoted SnXsub
- Lv, Feng Huan,Bi, Rui,Liu, Yu Hang,Li, Wen Sheng,Zhou, Xiao Ping
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- Interrupted oligomerization revisited: Simple and efficient one-pot multicomponent approach to versatile synthetic intermediates
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A novel multicomponent reaction allowing for a one-pot formation of three carbon-carbon bonds has been developed. It is based on in situ generation and anionic dimerization of methylenedithiane and produces a versatile synthetic equivalent of 4-hydroxy-1,3-alkanediones which, among other things, offers expeditious one-pot access to 3(2H)-furanones.
- Valiulin, Roman A.,Halliburton, Logan M.,Kutateladze, Andrei G.
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p. 4061 - 4063
(2008/02/11)
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- INDIRECT ELECTROCHEMICAL α-METHOXYLATION OF ALIPHATIC ETHERS AND ACETALS - REACTIVITY AND REGIOSELECTIVITY OF THE ANODIC OXIDATION USING TRIS(2,4-DIBROMOPHENYL)AMINE AS REDOX CATALYST
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The technically important α-methoxylation of aliphatic ethers and acetals to form mixed acetals respectively aldehydes or ortho-esters can be performed electrochemically at low potentials in methanol solution using an undivided cell and tris(2,4-dibromophenyl)amine as redox catalyst.The regioselectivity is usually considerably higher as compared with direct electrolysis in the abscence of a catalyst.Especially valuable is the method for the regioselective methoxylation of secondary carbon atoms in presence of primary or tertiary ones and of the acetal carbon in 1,3-dioxolanes.The redox catalyst is stable under the reaction conditions so that more than thousand turnovers could be obtained.
- Ginzel, Klaus-Dieter,Steckhan, Eberhard,Degner, Dieter
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p. 5797 - 5806
(2007/10/02)
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