High-resolution nuclear-magnetic-resonance spectra of hydrocarbon groupings II. Internal rotation in substituted ethanes and cyclic ethers
High-resolution nuclear-magnetic-resonance spectra of hydrocarbon groupings II. Internal rotation in substituted ethanes and cyclic ethers
复制标题
烃基团的高分辨率核磁共振谱 II。
DOI：
10.1098/rspa.1959.0169
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发表时间：
1959
期刊：
影响因子：
--
通讯作者：
J. J. Turner
中科院分区：
文献类型：
--
作者：
N. Sheppard;J. J. Turner
测定了式H3C中氯乙烷和溴乙烷的氢化学位移和相邻碳原子上氢核之间的JHH耦合常数。Ch´2z, h3c。Ch´z2, zh2c。Ch´z2, zh2c。CH´Z2和Z2HC。CH´Z2和环醚二恶烷、二恶alan和环氧乙烷。相邻碳上的氢核在化学上是相等的，如ZH2C式的分子。用13CH基团引起的氢共振光谱中的CH´2Z和z2h C .C H 'Z 2卫星来确定合适的耦合常数。为了改变旋向异构体的相对丰度，我们在不同介电常数的溶剂和液体状态下，对具有可区分旋向异构体的分子进行了研究。用这种方法得到了相对于彼此的反式和间扭式构象的氢原子对的耦合常数的不同值。反式偶联常数（9 ~ 18 c/s）明显大于间扭式偶联常数（1·2 ~ 3·5 c/s），且符号相同。在氯乙烷和溴乙烷系列中，实验观测到的平均JHH偶联常数的相当大的变化是由旋转异构引起的。
The hydrogen chemical shifts and the JHH' coupling constants between hydrogen nuclei on adjacent carbon atoms have been measured for the chloroethanes and bromoethanes of formula H3C . CH´2Z, H3C . CH´Z2, ZH2C . CH´Z2, ZH2C . CH´Z2 and Z2HC . CH´Z2 and for the cyclic ethers dioxan, dioxalan and ethylene oxide. Where hydrogen nuclei on adjacent carbons are chemically equivalent, as with molecules of formula ZH2C . CH´2Z and Z 2H C .C H 'Z 2, satellites in the hydrogen resonance spectra caused by 13CH groups have been used to determine the appropriate coupling constants. Those molecules which have distinguishable rotation al isomers have been studied in solvents of different dielectric constant, as well as in the liquid state, in order to vary the relative abundance of the isomers. By this means separate values have been obtained of coupling constants for pairs of hydrogen atoms that are in trans and gauche configurations with respect to each other. It is found that the trans coupling constants (9 to 18 c/s) are markedly greater than the gauche constants (1·2 to 3·5 c/s) and of the same sign. Considerable variations in the experimentally observed mean JHH' coupling constants within the series of chloro- and bromo- ethanes are caused by rotational isomerism.