THE O-18 ISOTOPE SHIFT IN C-13 NUCLEAR MAGNETIC-RESONANCE SPECTROSCOPY .13. OXYGEN-EXCHANGE AT THE ANOMERIC CARBON OF DEUTERIUM-GLUCOSE, DEUTERIUM-MANNOSE, AND DEUTERIUM-FRUCTOSE
THE O-18 ISOTOPE SHIFT IN C-13 NUCLEAR MAGNETIC-RESONANCE SPECTROSCOPY .13. OXYGEN-EXCHANGE AT THE ANOMERIC CARBON OF DEUTERIUM-GLUCOSE, DEUTERIUM-MANNOSE, AND DEUTERIUM-FRUCTOSE
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DOI：
10.1021/jo00289a026
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发表时间：
1990-01-19
影响因子：
3.6
通讯作者：
VANETTEN, RL
中科院分区：
文献类型：
--
作者：
MEGA, TL;CORTES, S;VANETTEN, RL
利用~（13）C NMR谱中的~（18）O同位素位移研究了D-葡萄糖、D-甘露糖和D-果糖异头碳原子上氧交换反应的动力学。交换反应遵循表观一级动力学，并随温度升高而增加。这些糖中的每一种的异头形式以大致相同的速率进行氧交换。这些单糖的氧交换反应由酸和碱催化，并且还观察到水反应。提供了详细的pH速率曲线。D-果糖在25 ℃下的氧交换速率与pH 2 - 6的甘露糖交换速率非常一致;然而，在pH 7以上，果糖的速率约为甘露糖速率的5倍。在26 ℃下，在pH 2-10范围内，D-甘露糖的氧交换速率约为D-葡萄糖的速率的5倍。这些糖和简单的醛和酮的水合速率之间的比较。可以估计邻近羟基的高有效摩尔浓度，这与快速变旋过程一致。有没有必要调用新的假无环中间体，以解释低（表观）速率的氧交换相比，变旋。
The 18O isotope shift in 13C NMR spectroscopy was used to study the kinetics of the oxygen exchange reaction at the anomeric carbon atoms of D-glucose, D-mannose, and D-fructose. The exchange reactions follow apparent first-order kinetics and increase with temperature. The anomeric forms of each of these sugars undergoes oxygen exchange at approximately the same rate. The oxygen exchange reactions of these monosaccharides are catalyzed by acid and by base, and a water reaction is also observed. Detailed pH-rate profiles are presented. The rate of oxygen exchange in D-fructose at 25.degree.C agrees closely with the mannose exchange rate from pH 2 to 6; however above pH 7 the rate for fructose is approximately 5 time the rate for mannose. At 26.degree.C the rate of oxygen exchange in D-mannose is approximately 5 times the rate for D-glucose over the pH range 2-10. Comparisons between the hydration rates for these sugars and for simple aldehydes and ketones are made. High effective molarities of neighboring hydroxyl groups may be estimated, consistent with the rapid mutarotation processes. There is no need to invoke novel pseudo-acyclic intermediates in order to explain the low (apparent) rate of oxygen exchange compared to mutarotation.