29Si NMR spectra of trimethylsilyl (TMS) derivatives of 26 simple alcohols were measured under standardized conditions (i.e., in sufficiently diluted deuteriochloroform solutions). Due to association with the solvent the chemical shifts are in almost all cases larger than those reported earlier for different solutions. This observation is in agreement with the proposed mechanism of steric effects as being due to sterically controlled association with the solvent. The use of chloroform as a solvent enhances steric effects but at the same time it can reduce small differences due to polar effects in closely related compounds. In the studied class of compounds the gross dependence of the chemical shift on polar effects is not substantially affected by the change of the solvent.
对26种简单醇类化合物的三甲基硅基(TMS)衍生物的硅核磁共振(29Si NMR)谱进行了测量,采用标准化条件(即,在充分稀释的氘代氯仿溶液中)。由于与溶剂的结合,化学位移在几乎所有情况下均大于早期报告的不同溶液的化学位移。这一观察结果与所提出的机制一致,即由于与溶剂的立体控制结合而产生的立体效应。氯仿作为溶剂的使用增强了立体效应,但同时也可以减小由于极性效应在密切相关化合物中的小差异。在所研究的化合物类别中,化学位移对极性效应的总体依赖性并未受到溶剂变化的实质影响。