Zhou Casey Chun, Hill David R
D-R418, Structural Chemistry, Global Pharmaceutical Research and Development, Abbott Laboratories, North Chicago, IL 60064, USA.
Magn Reson Chem. 2007 Feb;45(2):128-32. doi: 10.1002/mrc.1930.
The keto-enol tautomerism of ethyl butylryl acetate was studied in mixed solvents under a variety of experimental conditions. The direct measurement of ketonization of the enol tautomer was performed by using the hyphenated technique LC-NMR. The keto and enol tautomers can be separated by using HPLC and their interconversion is a slow process on the NMR timescale. The ketonization reaction was found to be acid catalyzed and the solvent isotope effect, kH2O/kD2O, in an acetonitrile/water mixture, is 5.4. The ketonization rate constants were also measured at different compositions of binary solvents, such as CH3CN/D2O, CD3OD/D2O, and CH3CN/CD3OD. The rate constant and water percentage were found to have an exponential relationship. The reaction rate as a function of solvent polarity will be discussed in this paper.
在多种实验条件下，研究了乙酸丁基乙烯酯在混合溶剂中的酮 - 烯醇互变异构现象。采用联用技术LC - NMR对烯醇互变异构体的酮化反应进行直接测定。通过高效液相色谱法（HPLC）可分离酮式和烯醇式互变异构体，并且在核磁共振（NMR）时间尺度上，它们之间的相互转化是一个缓慢的过程。发现酮化反应是酸催化的，在乙腈/水混合物中的溶剂同位素效应kH₂O/kD₂O为5.4。还在二元溶剂的不同组成下，如CH₃CN/D₂O、CD₃OD/D₂O和CH₃CN/CD₃OD，测定了酮化速率常数。发现速率常数与水的百分比呈指数关系。本文将讨论反应速率与溶剂极性的函数关系。
