The Stereochemistry of α-Haloketones. I. The Molecular Configurations of Some Monocyclic α-Halocyclanones
The Stereochemistry of α-Haloketones. I. The Molecular Configurations of Some Monocyclic α-Halocyclanones
复制标题
α-卤代酮的立体化学 I. 一些单环 α-卤代环酮的分子构型。
DOI：
10.1021/ja01106a004
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发表时间：
1953
影响因子：
15
通讯作者：
E. Corey
中科院分区：
文献类型：
--
作者：
E. Corey
用红外光谱法测定了几种单环卤代酮的分子构型。2-溴-4，4-二甲基环己酮和7-溴螺[4.5]癸烷-6-酮的最稳定构象是卤素取代基为平性的椅型构象。对α-氯代环己酮和α-溴代环己酮的计算结果与计算结果一致，表明在决定分子构型时，取代基间的偶极-偶极相互作用比空间相互作用更重要。2-溴-4，4-二甲基环己酮和7-溴-螺[4.5]癸烷-6-酮的结果表明克服相反的电相互作用所需的空间相互作用的大小。最近的工作表明，环己烷衍生物的“椅式”构象比“船式”构象能量低得多。1· 2-3例如，环己烷的椅式形式本身的能量是ca。5.6千卡/摩尔比小于船型。3此外，两者之间通常存在明显的能量差
The molecular configurations of several monocyclic-haloketones havebeen determined by means of infrared spectroscopy. The most stableconformation of-chlorocyclohexanone and of-bromoeyclohexanone is that chair formin which the halogen substituent is polar, while the most stable conformation of 2-bromo-4, 4-dimethylcyclohexanone and of 7-bromospiro [4.5] decane-6-one is that chair formin which the halogen substituent is equatorial. The results with a-chlorocyclo-hexanone and-bromocyclohexanone are in agreement with calculations which clearly show that with these substances di-pole-dipole interaction is more important thansteric interaction between substituents in determining molecular configuration. The results with 2-bromo-4, 4-dimethylcyclohexanone and 7-bromo-spiro [4.5] decane-6-one indicate the magnitude of the steric interaction needed to overcome the opposing electrical interaction. Information is also provided concerning the molecular configurations of-chlorocycloheptanone and a-bromocycloheptanone.Recent work has shown that the “chair” confor-mation of cyclohexane derivatives is of considerably lower energy than the “boat” conformation. 1· 2-3 The energy of the chair form of cyclohexane itself, for example, is ca. 5.6 kcal./mole less than that of the boat form. 3 Furthermore, an appreciable energy difference usually exists between the two