Barriers to exchange between dl and meso forms via rotation about the C9–Csubst bond of 9-(arylmethyl)-1,4-dimethoxytriptycenes are obtained by the use of the methoxyl signals in the 1H NMR spectra. It is found that, although the population ratios are affected by the substituent in the 9 position, the enthalpy of activation for the rotation is almost invariant at ca. 10 kcal/mol.
通过利用 1H NMR 光谱中的甲氧基信号,得出了 9-(芳基甲基)-1,4-二甲氧基三
联苯通过围绕 C9-Csubst 键旋转在 dl 和 meso 形式之间进行交换的障碍。研究发现,虽然种群比率受 9 位取代基的影响,但旋转的活化焓几乎不变,约为 10 kcal/mol。10 千卡/摩尔。