The population ratios ±sc/ap in 9-(aryloxymethyl)-1,4-dimethyltriptycenes were determined by 1H NMR spectroscopy. Whereas electron-withdrawing substituents favor the ap rotamer, electron-donating substituents favor the ±sc rotamer in a relative sense. The results are attributed to the presence of weak CH3···O intramolecular hydrogen bond in the ±sc form.
通过 1H NMR 光谱测定了 9-(芳氧基甲基)-1,4-二甲基三
联苯中的±sc/ap 群比率。取电子取代基有利于 ap 转子,而供电子取代基则相对有利于 ±sc 转子。这些结果归因于±sc形式中存在微弱的
CH3--O分子内氢键。