The sulfur-inversion in the title compound (alkyl=ethyl) was found to take place with the following activation parameters by dynamic NMR spectroscopy: ΔH\eweq=23.8±0.2 kcal mol−1, ΔS\eweq=2.6±0.4 cal mol−1 K−1. The significance of the near zero entropy of activation is discussed. The mesityl group in the title compounds also showed restricted rotation of which barrier to rotation was estimated to be 14 kcal mol−1 at 318 K for the compound where the alkyl is a methyl.
通过动态核磁共振波谱发现标题化合物(烷基=乙基)中的
硫转化发生在以下活化参数下:ΔH\eweq=23.8±0.2 kcal mol−1,ΔS\eweq=2.6±0.4 cal mol−1 1 K−1。讨论了接近零的激活熵的重要性。标题化合物中的异三叉基也显示出旋转受限,对于烷基为甲基的化合物,在 318 K 下估计旋转势垒为 14 kcal mol−1。