The methyls in a t-butyl group are shown to exhibit different reactivities in radical halogenations, if rotation about a (CH3)3C–CXY2 bond is frozen. Barriers to rotation of halogenated 9-t-butyl-1,2,3,4-tetrachlorotriptycenes are obtained as ΔH\eweq ca. 32 kcal/mol. The cause of the selectivity in chlorination with sulfuryl chloride was discussed by obtaining reactivity data with a variety of compounds
如果围绕 (CH3)3C-CXY2 键的旋转被冻结,则叔丁基中的甲基在自由基卤化中表现出不同的反应性。卤化 9-t-丁基-1,2,3,4-四氯三苯环的旋转障碍作为 ΔH\eweq ca 获得。32 大卡/摩尔。通过获得与多种化合物和卤化试剂的反应数据,讨论了磺酰氯氯化选择性的原因。得出的结论是,周围卤素取代基的相邻基团参与是造成观察到的选择性的原因。