Noroozi Pesyan Nader
Department of Chemistry, Faculty of Science, Urmia University, 57159, Urmia, Iran.
Magn Reson Chem. 2011 Sep;49(9):592-9. doi: 10.1002/mrc.2790. Epub 2011 Aug 5.
Isotopic effect on tautomeric behaviors of the synthesized 5-phenoxy- (1a), 5-(2,6-dimethylphenoxy)-(1b), 5-(2,6-diisopropylphenoxy)-(1c), 5-(2,6-dimethoxyphenoxy)-(1d) and 5-(4-methylphenoxy)-tetrazole (1e) were investigated in DMSO-d6 by adding one drop of D2O. Among 1a-e, 1a, 1d and 1e show small rotational barrier around C5-O1 and O1-C6 while in 1b and 1c there are distinguishable rotational barrier about that bonds. The (1)H NMR spectra of 1b and 1c show slightly different chemical shifts for two methyl and isopropyl groups on those phenyl ring, respectively, while the chemical shifts difference (Δδ) between two methyl and two isopropyl groups were enhanced by adding D2O. The (13)C NMR spectra of 1b show two overlapped singlets for methyl groups after adding D2O. Representatively, the calculations of compound 1c were performed with GAUSSIAN-03 and the rotational barrier about C5-O1 and between isopropyl group and phenyl ring in 1c was calculated with B3LYP/6-31G(d) basis set.
通过添加一滴重水（D₂O），在氘代二甲亚砜（DMSO-d₆）中研究了合成的5-苯氧基-（1a）、5-（2,6-二甲基苯氧基）-（1b）、5-（2,6-二异丙基苯氧基）-（1c）、5-（2,6-二甲氧基苯氧基）-（1d）和5-（4-甲基苯氧基）-四唑（1e）的互变异构行为的同位素效应。在1a - e中，1a、1d和1e在C5 - O1和O1 - C6周围显示出较小的旋转势垒，而在1b和1c中，围绕这些键存在明显的旋转势垒。1b和1c的¹H NMR谱分别显示苯环上两个甲基和异丙基的化学位移略有不同，而添加D₂O后两个甲基和两个异丙基之间的化学位移差值（Δδ）增大。添加D₂O后，1b的¹³C NMR谱显示甲基为两个重叠的单峰。代表性地，使用GAUSSIAN - 03对化合物1c进行计算，并使用B3LYP/6 - 31G(d)基组计算1c中C5 - O1以及异丙基与苯环之间的旋转势垒。
