AROMATIC SUBSTITUION .8. MECHANISM OF NITRONIUM TETRAFLUOROBORATE NITRATION OF ALKYLBENZENES IN TETRAMETHYLENE SULFONE SOLUTION - REMARKS ON CERTAIN ASPECTS OF ELECTROPHILIC AROMATIC SUBSTITUTION
AROMATIC SUBSTITUION .8. MECHANISM OF NITRONIUM TETRAFLUOROBORATE NITRATION OF ALKYLBENZENES IN TETRAMETHYLENE SULFONE SOLUTION - REMARKS ON CERTAIN ASPECTS OF ELECTROPHILIC AROMATIC SUBSTITUTION
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DOI：
10.1021/ja01483a017
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发表时间：
1961-01-01
影响因子：
15
通讯作者：
FLOOD, SH
中科院分区：
文献类型：
--
作者：
OLAH, GA;KUHN, SJ;FLOOD, SH
用InGold的竞争硝化法测定了烷基苯和苯在四亚甲基砜溶液中与四氟硼酸硝铵均相一次硝化反应的相对反应性。用气-液色谱分析了产物的相对反应性和异构体分布。得到的相对速率与烷基苯类化合物(Ag+、Br2、I2、ICl、苦味酸、HCl、HF)的相对络合稳定性有很好的相关性，而与相对络合稳定性(HF+BF)无相关性。反应机理被认为是N02+与芳烃之间形成定向(或局域)络合物的主要速率控制步骤。这符合这样一个事实，即部分速率因子和经验选择性因子不适用于目前的体系(主要竞争是供体分子之间的竞争，而不是这些分子的个别位置)。苯-D6和甲苯-DS的硝化反应表现出较小的二次逆动力学同位素效应(重化合物反应较快)。根据所获得的实验数据，对四氟硼酸硝化烷基苯的反应机理进行了讨论。
Ingold’s method of competitive nitration has been used in order to determine relative reactivities of alkylbenzenes and benzene in homogeneous mononitrations with nitronium tetrafluoroborate in tetramethylene sulfone solutions. Relative reactivities and isomer distributions were determined by gas-liquid chromatography. The obtained relative rates show a good correlation with relative-complex stabilities of alkylbenzenes (Ag+, Br2, I2, I Cl, picric acid, HC1, HF), but not with-complex stabilities (HF+ BFs). The reaction mechanism is considered to involve oriented (or localized)-complex formation between N02+ and the aromatics as the main rate-determining step. This is in accordance with the fact that partial rate factors and empirical selectivity factors are not applicable to present systems (primary competition is between donor molecules as such and not individual positions of those). The nitration of benzene-d6 and toluene-ds shows a small secondary reverse kinetic isotope effect (the heavy compound reacting faster). The mechanism of the investigated nitration of alkylbenzenes with nitronium tetrafluoroborate is discussed in the light of the obtained experimental data.