Institute of Non-Ferrous Metals, ul. Sowinskiego 5, 44-100 Gliwice, Poland.
Phys Chem Chem Phys. 2014 Mar 14;16(10):4694-8. doi: 10.1039/c3cp54833c.
It is a well known fact that carbohydrates have unusual chemical and physical properties when they approach the glassy state during the cooling process. Differences between sugar aqueous solutions and their pure anhydrous states are caused mainly by the different intermolecular interactions related to the different hydrogen bond patterns. The mutarotation, a specific reaction in the saccharides, was recently investigated in the supercooled liquid and the glassy state of D-glucose. It was shown that the activation energy of this process in the supercooled liquid state is twice as low as for the same process in aqueous solution. In contrast, the activation energy in the glassy state is twice as high as in the aqueous solution. Herein, we present possible explanations for this phenomenon and propose a universal mechanism for the mutarotation process in the amorphous state of matter. In this work, for the first time, a double proton exchange mechanism in carbohydrates is proposed.
众所周知，当碳水化合物在冷却过程中接近玻璃态时，它们具有异常的化学和物理性质。糖水溶液与其纯无水状态之间的差异主要是由于不同的分子间相互作用与不同的氢键模式有关。最近，在 D-葡萄糖的过冷液体和玻璃态中研究了一种特定的糖反应——差向异构化。结果表明，该过程在过冷液体状态下的活化能比在水溶液中的相同过程低两倍。相比之下，在玻璃态下的活化能比在水溶液中高两倍。在此，我们对这一现象提出了可能的解释，并为无定形物质中的差向异构化过程提出了一个通用的机制。在这项工作中，首次提出了碳水化合物中的双质子交换机制。
