9-ethyl-1,4-dimethyltriptycene were prepared. The 13C NMR spectra of these compounds were measured at low temperatures in order to obtain information about the restricted rotation of the ethyl group. It was found that the former two compounds have the meso isomer as well as the dl isomer. Different chemical shifts of the methylene carbons in the ethyl group, C(2) and C(3) of the benzene A ring, and some quaternary
制备了 9-乙基-1,4-二甲氧基三苯、1,5-二
氯-9-乙基三苯和 9-乙基-1,4-二甲基三苯。这些化合物的 13C NMR 光谱在低温下测量,以获得关于乙基旋转受限的信息。发现前两种化合物具有内消旋异构体和dl异构体。乙基中的亚甲基碳、苯 A 环的 C(2) 和 C(3) 以及 9-乙基-1,4-二甲氧基三苯环的两种异构体中的一些季碳的不同
化学位移表明 120° C围绕乙基中Csp3-Csp3单键的旋转使苯或双环[2.2.2]辛
三烯骨架变形。对该化合物的温度相关 13C NMR 谱进行了完整的线形分析,并确定了乙基旋转的热力学静态参数和活化参数。简要讨论了烷基的旋转势垒与其体积之间的相关性。