Insights into the isomerization of xylose to xylulose and lyxose by a Lewis acid catalyst
Insights into the isomerization of xylose to xylulose and lyxose by a Lewis acid catalyst
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DOI：
10.1016/j.carres.2012.12.019
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发表时间：
2013-03-07
影响因子：
3.1
通讯作者：
Vlachos, Dionisios G.
中科院分区：
文献类型：
--
作者：
Choudhary, Vinit;Caratzoulas, Stavros;Vlachos, Dionisios G.
我们用分子筛SnBEA模型在MP2和B3LYP水平上对木糖异构化和异构化分别进行了电子结构计算。还给出了CCSD(T)理论层面的基准计算。我们证明，粘糖是由木性腺果糖异构化途径中的稳定中间体形成的。与实验观察一致，我们预测木糖在热力学和动力学上比粘糖更受青睐。我们发现这两个反应最慢的步骤都涉及到从碳水化合物分子的C2到C1碳的氢转移，并用自然布居分析对其进行了表征。我们的结论是，氢转移不是以氢化物离子的形式发生的，而是协调的中性氢-电子转移，涉及氢和电子转移的不同中心。(C)2012爱思唯尔有限公司。保留所有权利。
We present electronic structure calculations on the isomerization and epimerization of xylose to xylulose and lyxose, respectively, by a zeolite SnBEA model at the MP2 and B3LYP theory levels. Benchmarking calculations at the CCSD(T) theory level are also presented. We show that lyxose is formed from a stable intermediate in the xylosexylulose isomerization pathway. In agreement with experimental observations, we predict that xylulose is thermodynamically and kinetically favoured over lyxose. We find that the slowest step for both reactions involves hydrogen transfer from the C2 to the C1 carbon of the carbohydrate molecule and we characterize it using natural population analysis. We conclude that the hydrogen transfer does not take place as a hydride ion but rather as concerted neutral hydrogen-electron transfer that involves different centres for the hydrogen and electron transfer. (C) 2012 Elsevier Ltd. All rights reserved.