(E)-2,3-Dibromo-2-hexene | 49677-08-9

• 分子结构分类: 有机化合物 - 有机卤素化合物
• 英文名称: (E)-2,3-Dibromo-2-hexene
• 英文别名: (E)-2,3-dibromohex-2-ene；(E)-2,3-dibromo-hex-2-ene
• CAS: 49677-08-9
• 化学式: C₆H₁₀Br₂
• 分子量: 241.953
• InChiKey: VTXYMTFWTSLYAP-AATRIKPKSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  3.4
• 重原子数：
  8
• 可旋转键数：
  2
• 环数：
  0.0
• sp3杂化的碳原子比例：
  0.67
• 拓扑面积：
  0
• 氢给体数：
  0
• 氢受体数：
  0

反应信息

• 作为反应物：
  描述：

  (E)-2,3-Dibromo-2-hexene 在 N-溴代丁二酰亚胺(NBS) 、 过氧化苯甲酰 作用下， 生成 (E)-1,2,3,4-tetrabromo-hex-2-ene
  参考文献：
  名称：

  Koester,R. et al., Justus Liebigs Annalen der Chemie, 1973, p. 1241 - 1251

  摘要：

  DOI：
• 作为产物：
  描述：

  2-已炔 在 oxone||potassium monopersulfate triple salt 、 potassium bromide 、 N-butyl-2-methylbenzamide 作用下， 以 二氯甲烷 、 水 为溶剂， 反应 0.33h， 以82%的产率得到(E)-2,3-Dibromo-2-hexene
  参考文献：
  名称：

  卤代碳环化与二卤代：取代基导向的碘（III）催化卤代。

  摘要：

  碘苯预催化剂中取代基的亲核性对碘（III）引发的卤化反应中的产物选择性产生巨大影响，使反应性从单纯的碳环化转向二卤化。利用这种依赖于催化剂的反应性，建立了非对映和化学选择性二卤化方法，该方法可以以优异的产率转化结构上和电子上不同的不饱和化合物。

  DOI：

  10.1039/c3cc49850f

文献信息

• Spectroscopic and Theoretical Investigations of Electrophilic Bromination Reactions of Alkynes: The First Evidence for π Complexes as Reaction Intermediates
  作者：Roberto Bianchini、Cinzia Chiappe、Giacomo Lo Moro、Dieter Lenoir、Peter Lemmen、Norman Goldberg

  DOI：10.1002/(sici)1521-3765(19990503)5:5<1570::aid-chem1570>3.0.co;2-a

  日期：1999.5.3

  A bromine-alkyne pi complex (lambda(max) = 294 nm) of 1:1 stoichiometry has been observed for the first time in the course of the bromination of 1-phenylpropyne by means of a diode-array stopped-flow technique. The formation enthalpy and entropy (Delta H?= -2.95 kcalmol(-1), Delta S-25?=-15.4eu) of this species are similar to those of charge-transfer complexes observed between bromine and alkenes. A negative apparent activation energy is found in the reaction of Br, with 1-phenylpropyne (Delta H-not equal=-0.61 kcalmol(-1)); this demonstrates that the complex is actually an essential intermediate on the reaction coordinate. The bromination of a series of nine alkynes has been studied. Bromination reactions with negative apparent activation parameters lead to mixtures of E and Z vinyl dibromides, whereas reactions with positive activation energy yield the E isomers exclusively. The reason for the difference in reactivity of these alkynes compared with structurally similar alkenes most likely lies in the stability of these 1:1 charge-transfer complexes. Usually open arylvinyl cations correspond to the energetically favored product-determining intermediates; bridged bromirenium ions are formed from deactivated alkynes and react to give E isomers. The kinetic effect of alkyl groups and of p-OCH3, p-CN, and p-NO2 substituents at the aryl group on the bromination of arylalkylacetylenes is discussed. Density functional calculations provide insight into the geometries, energies, and bonding of the intermediate 1:1 and 2:1 Br-2-acetylene complexes involved. These theoretical investigations demonstrate that the most stable trimolecular Br-2-Br-2-acetylene adduct possesses a structure very similar to a crystallographically characterized Br-2-Br-2-alkene species, which can directly yield the ionic products, Br-3(-) and vinyl cation, driven by the heterolytic action of a solvent.