Nuclear Magnetic Resonance Study of Exchanging Systems. X. Rotational Barriers to trans-cis Isomerization in Esters
Nuclear Magnetic Resonance Study of Exchanging Systems. X. Rotational Barriers to trans-cis Isomerization in Esters
复制标题
交换系统的核磁共振研究。
DOI：
10.1246/bcsj.51.214
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发表时间：
1978
影响因子：
4
通讯作者：
O. Yamamoto
中科院分区：
文献类型：
--
作者：
H. Nakanishi;H. Fujita;O. Yamamoto
测定了甲酸叔丁酯(1)、1，1-二乙基甲酸丙酯(2)和2，6-二甲基苯基甲酸酯(3)在不同温度下的~(13)C核磁共振谱。结果发现，在很低的温度下，1和2的反式和顺式异构体的信号是分离的，而3的信号只有轻微的谱线展宽。对这些随温度变化的光谱进行了完整的线形分析。由反式异构体到顺式异构体的异构化反应活化能Ea(t-c)分别为10.9千卡/摩尔和7.2千卡/摩尔。
The 13C NMR spectra of t-butyl formate (1), 1,1-diethylpropyl formate (2), and 2,6-dimethylphenyl formate (3) were measured at various temperatures. It was found that the signals of the trans and cis isomers in 1 and 2 are separated at very low temperatures, and that the signal of 3 only shows a slight line broadening. The complete line shape analyses of these temperature-dependent spectra were performed. The activation energies Ea(t-c) of the isomerization from the trans isomer to the cis were determined to be 10.9 kcal/mol for 1 and 7.2 kcal/mol for 2.