SURFACE-MEDIATED REACTIONS .3. HYDROHALOGENATION OF ALKENES
SURFACE-MEDIATED REACTIONS .3. HYDROHALOGENATION OF ALKENES
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DOI：
10.1021/ja00061a005
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发表时间：
1993-04-21
影响因子：
15
通讯作者：
BRETON, GW
中科院分区：
文献类型：
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作者：
KROPP, PJ;DAUS, KA;BRETON, GW
已发现，适当制备的硅胶和氧化铝可以促进HCl、HBr和HI与烯烃的加成反应。通过使用各种有机和无机卤化物，在硅胶或氧化铝存在下进行水解，原位生成卤化氢，这项技术变得更加方便。在这些条件下，环庚烯(1)、1-辛烯(7)和3，3-二甲基-1-丁烯(15)等在溶液中与HCl反应非常缓慢的烯烃可以快速加成。1-辛烯(7)在没有竞争自由基加成的情况下与HBr发生离子加成反应。1，2-二甲基环己烷(24)得到了与热力学上更稳定的异构体25T平衡的合成产物25C。提出了一种表面介导的加成/消除机制，涉及H+和X-以同步方式从表面逐步转移到表面或转移到表面，如方案II所示。
Appropriately prepared silica gel and alumina have been found to mediate the addition of HCl, HBr, and HI to alkenes. The technique has been rendered even more convenient by the use of various organic and inorganic halides that undergo hydrolysis in the presence of silica gel or alumina to generate hydrogen halides in situ. Under these conditions alkenes such as cycloheptene (1), 1-octene (7), and 3,3-dimethyl-1-butene (15), which react with HCl only very slowly in solution, underwent rapid addition. 1-Octene(7) underwent ionic addition of HBr without competing radical addition. 1,2-Dimethylcyclohexane (24) afforded the syn addition product 25c, which underwent equilibration with the thermodynamically more stable isomer 25t. A mechanism for surface-mediated addition/elimination is proposed involving a stepwise transfer of H+ and X- from or to the surface in syn fashion, as shown in Scheme II.