Nuclear magnetic resonance spectroscopy. Conformational equilibria and rates of conformational interconversion of halogenated ethanes
作者:Frank J. Weigert、Meldrum B. Winstead、James I. Garrels、John D. Roberts
DOI:10.1021/ja00728a020
日期:1970.12
lowest field. All three barriers for interconversion could be determined for the ethanes substituted so as to give three distinguishable conformations. For these cases it was found that the highest barrier separates the two least populated conformations and the lowest barrier separates the most stable conformations. The substances for which complete nmr line-shape analysis have given the equilibrium
一些卤代乙烷的旋转异构体的相对基态能量以及这些异构体相互转化的速率和势垒已通过核磁共振光谱确定。在本研究中研究的乙烷中,发现具有单一氟的那些在最高场中具有最少人口构象的 ^(19)F 共振,而在最低场中发现人口最多的构象。对于取代的乙烷,可以确定所有三个相互转化的障碍,以便给出三个可区分的构象。对于这些情况,发现最高的屏障分隔了两个最少人口的构象,而最低的屏障分隔了最稳定的构象。完全核磁共振线形分析已给出平衡常数的物质,速率和内部轮换的障碍包括 1,1,2-tribromo-1,2-dichloro-2-fluoroethane, 1,1-dibromo-1,2,2-trichloro-2-fluoroethane, 1-bromo-1, 1,2,2-四氯-2-氟乙烷,1,1,2,2-四溴-1-氯-2-氟乙烷,1,2-二溴-1,1,2-三氯-2-氟乙烷,1, 1,2-三溴-1-氯-2-氟乙烷,1-溴-1