ANIONIC ACTIVATION OF C-H BONDS IN OLEFINS .4. EFFECT OF RING SIZE ON RATE OF FORMATION OF ANIONS FROM ALKYLIDENECYCLOALKANES AND CYCLOALKANONES
ANIONIC ACTIVATION OF C-H BONDS IN OLEFINS .4. EFFECT OF RING SIZE ON RATE OF FORMATION OF ANIONS FROM ALKYLIDENECYCLOALKANES AND CYCLOALKANONES
复制标题
DOI：
10.1021/ja00875a026
复制
发表时间：
1962-01-01
影响因子：
15
通讯作者：
ROWE, CA
中科院分区：
文献类型：
--
作者：
SCHRIESHEIM, A;MULLER, RJ;ROWE, CA
研究了起始双键位于环外的环烯烃的异构化反应。采用均相催化体系叔丁醇钾-二甲基亚砜，测定了反应的速率常数、活化能和熵。发现异构化速率是环尺寸的函数，并且以下反应性顺序保持在55：成核，1070; C5-环，454; Ce-环，1; C1-环，5.8; Cs-环，17。在异构化速率和碱催化溴化反应速率之间得到了线性自由能关系。结果是可解释的基础上的速率决定步骤，涉及质子的去除，然后由-键再杂交，形成一个烯丙基阴离子系统。立体电子因素被假定在建立这样的系统中发挥关键作用。
The isomerization of cyclic olefins in which the starting double bond is exocyclic to the ring has been studied. A homogeneous catalyst system, potassium ZerZ-butoxide-dimethyl sulfoxide ivas used and the rate constants, activation energies and entropies were obtained. It was found that the isomerization rates were a function of ring size and the following order of reactivities holds at 55: Coring, 1070; C5-ring, 454; Ce-ring, 1; Ci-ring, 5.8; Cs-ring, 17. A linear free-energv relation-ship was obtained between the isomerization rates and the rates for the base-catalyzed bromination of structurally similar ketones. The results are interpretable on the basis of a rate-determining step involving the removal of a proton followed by--bond rehybridization to form an allylic anionic system. Stereoelectronic factors are postulated to play a key role in establishing such a system.