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DFT mechanistic study of reactions of С6H6 and 1,3,5-Ad3C6H3 with CBr3. The first example of hydride transfer from aromatic CH bond to electrophile
Journal of Molecular Catalysis A: Chemical Pub Date : 2016-10-24 , DOI: 10.1016/j.molcata.2016.10.027
Yurii A. Borisov , Irena S. Akhrem

The DFT B3LYP/6-31G* calculations were carried out for the reactions of C6H6 and Ad3C6H3 (Ad = 1,3,5-adamantyl) with superelectrophile CBr3+ as a model of superelectrophilic catalyst CBr3+ Al2Br7. The reaction of C6H6 with CBr3+ proceeds via the classical scheme of electrophilic reactions of aromatic C − H bond to form initially the barrier-free σ-complex C6H6CBr3+. This mechanism was confirmed by the aug-cc-pVDZ basis set calculations. The reaction of Ad3C6H3 with CBr3+ occurs via a quite novel mechanism involving aryl cation formation followed by hydride abstraction of the Ar+ from the 2-Ad group and the rearrangement of the 2-Ad+ cation into the 4-phenyl-4-protoadamantyl cation. The hydride transfer from both arenes was shown to be more favorable than H radical transfer by more than 40 and 55 kcal mol−1 in the case of C6H6 and Ad3C6H3, respectively.



中文翻译:

С的反应的DFT机理研究6 ħ 6和1,3,5-广告3 Ç 6 ħ 3与CBR 3。氢化物从芳族C H键转移至亲电试剂的第一个例子

对于C 6 H 6和Ad 3 C 6 H 3(Ad = 1,3,5-金刚烷基)与超亲电试剂CBr 3 +的反应进行了DFT B3LYP / 6-31G *计算,作为超亲电催化剂CBr的模型3 +的Al 27 - 。C的反应6 ħ 6与CBR 3个+前进通过芳族C的亲电反应的经典方案- H键以形成最初的无障碍-σ-络合物C 6 H ^ 6 CBR 3 +。通过aug-cc-pVDZ基集计算确认了该机制。Ad 3 C 6 H 3与CBr 3 +的反应通过一种非常新颖的机理发生的该机理涉及芳基阳离子的形成,然后将Ar +的氢化物从2-Ad基团中提取出来,然后将2-Ad +阳离子重排成4个基团。 -苯基-4-原金刚烷基阳离子。在C 6 H 6和Ad 3 C 6 H 3的情况下,从两个芳烃的氢化物转移均比H自由基转移更有利,其转移量大于40和55 kcal mol -1, 分别。

更新日期:2016-10-24
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