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第四级铵碱Hofmann消除反应的研究Ⅱ.——关于Hofmann消除反应的构象规则 被引量:2

Studies of the Thermal Elimination of Quaternary Ammonium Hydroxides Ⅱ On the Conformational Rule for Hofmann Elimination
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摘要 本文制备了七个各含有一个异己基的第四级铵碱,并使之发生Hofmann消除反应。目的是为了给异己基在Hofmann消除反应的构象规则消除易度序列中确定其位置,并探索异己基在该消除反应中的机理倾向。气相色谱分析的结果表明异己基比异戊基和异丁基容易消除,属于“含侧链较远的第一级烷基”,并且其反应过程倾向于反式E_2机理。 Seven quaternary ammonium hydroxides iso-Hex-NMe2-R OH-, in which the R group equals to Et, n-Pr, iso-Pr, n-Bu, iso-Bu, sec-Bu and iso-Am respectively, were prepared and subjected to Hofmann Elimination. It can be seen from Table Ⅱ that:(1) Et, n-Pr, iso-Pr, sec-Bu and n-Bu are the alkyl groups eliminated easier than iso-Hex group, while iso-Bu and iso-Am are the alkyl groups eliminated more difficult than iso-Hex group. This result means that iso-Hex group can be put in the Reactivity Sequence for Alkyl Groups proposed for the Conformational Rule and can be considered as 'a primary alkyl group with a remote side alkyl group'.(2) The fact that iso-Hex group eliminated easier than iso-Am group implicates that the elimination of iso-Am and iso-Hex groups tends to the trans E2 mechanism rather than to the cis one, since it has been shown by calculation that via the trans, mechanism the energy of the needed conformation for iso-Hex group is lower than that for iso-Am group, while via the cis mechanism the situation is just opposite.
出处 《北京大学学报(自然科学版)》 CAS CSCD 北大核心 1990年第2期214-218,共5页 Acta Scientiarum Naturalium Universitatis Pekinensis
关键词 Hofmann 消除反应 第四级铵碱 Hofmann elimination Conformational rule Quaternary ammonium hydroxide iso-Amyl group iso-Hexyl group
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参考文献6

  • 1徐筱杰,姚振贵,叶秀林,唐有祺,傅亨,钱民协.第四级铵氢氧化物Hofmann消除反应的构象分析及反应机理[J].物理化学学报,1989,5(4):398-402. 被引量:2
  • 2马殿英,山东省科学院院刊,1988年,1卷,1期,43页
  • 3姚振贵,1987年
  • 4郭静,高等学校化学学报,1985年,6卷,11期,1000页
  • 5叶秀林,化学通报,1981年,12期,40页
  • 6叶秀林,化学通报,1981年,11期,47页

二级参考文献2

  • 1郭静,高等学校化学学报,1985年,6卷,11期,1000页
  • 2叶秀林,化学通报,1981年,11卷,47页

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