The Mutarotation of Glucose in Dimethylsulfoxide and Water Mixtures
The Mutarotation of Glucose in Dimethylsulfoxide and Water Mixtures
复制标题
葡萄糖在二甲亚砜和水混合物中的变旋
DOI：
10.1139/v73-085
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发表时间：
1973
影响因子：
1.1
通讯作者：
E. Robertson
中科院分区：
文献类型：
--
作者：
N. M. Ballash;E. Robertson
葡萄糖的变旋反应是一个普遍的酸碱催化反应，涉及两个质子转移。无论这些质子转移是以逐步或协调的方式进行的，后者的替代方案可能包括几个水分子在一个循环的过渡态，是不知道的certaints.This研究进行了试图澄清的机制，直接确定参与过渡态的水分子的数量。所选择的方法是确定葡萄糖的酸催化变旋率作为溶剂组合物在二甲基亚砜和水的混合物中的函数，特别是在水贫乏的区域。结果表明，对于酸催化反应，水的反应级数为零。对于水催化，结果不太可靠，但表明可能涉及大约三个水分子。这些事实被解释为意味着一个逐步的机制是在质子催化反应，但溶剂的操作。
The mutarotation of glucose is a general acid – base-catalyzed reaction which involves two proton transfers. Whether these proton transfers are carried out in a stepwise or concerted manner, the latter alternative possibly incorporating several water molecules in a cyclic transition state, is not known with certainty.This study was undertaken in an attempt to clarify the mechanism by determining directly the number of water molecules participating in the transition state. The method chosen was to determine rates for the acid-catalyzed mutarotation of glucose as a function of solvent composition in dimethylsulfoxide and water mixtures, particularly in the water poor region. The results show that for the acid-catalyzed reaction the order with respect to water is zero. For water catalysis, the results are less reliable but suggest that about three water molecules may be involved. These facts are interpreted to mean that a stepwise mechanism is operative in the proton-catalyzed reaction, but that the solvent-...