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首页> 外文期刊>Chemistry: A European journal >The Ambident Reactivity of 2,4,6-Tris(trifluoromethanesulfonyl)anisole in Methanol: Using the SO2CF3 Group as a Tool to Reach the Superelectrophilic Dimension in s-Complexation Processes
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The Ambident Reactivity of 2,4,6-Tris(trifluoromethanesulfonyl)anisole in Methanol: Using the SO2CF3 Group as a Tool to Reach the Superelectrophilic Dimension in s-Complexation Processes

机译：2,4,6-三（三氟甲磺酰基）苯甲醚在甲醇中的环境反应性：使用SO2CF3基团作为工具在s络合过程中达到超亲电尺寸

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摘要

The kinetics of s complexation of 2,4,6-tris trifluoromethanesulfonyl) anisole (7d) have been investigated over a large pH range of 2–13.70 at T=20 8C in methanol. Two competitive processes associated with the initial addition of MeOe at the unsubstituted 3-position of 7d to give a 1,3-dimethoxy adduct (9d-Me) and a subsequent and slow conversion of this species into a 1,1-dimethoxy isomer (8d-Me) have been identified. Both adducts 8d-Me and 9d-Me are 105–106 times more stable than the related adducts 8a-Me and 9a-Me of 2,4,6-trinitroanisole (7a), a conventional reference aromatic electrophile in Meisenheimer complex chemistry. The high stability of 8d-Me and 9d-Me is shown to derive from greater rates of formation and lower rates of decomposition than previously determined for 8a-Me and 9a-Me, thereby emphasising the especially high activation of a benzene ring by SO2CF3 group(s). Analysis of the collected rate and equilibrium data for s complexation in the anisole series 2,4,6-trisACHTUNGTRENUNG(SO2CF3)-, 2,6-bisACHTUNGTRENUNG(SO2CF3)-4- nitro-, 4-SO2CF3-2,6-dinitro- and 2,4,6- trinitro- supports the idea that the especially high capacity of resonance stabilisation of the negative charge of the adducts through an Fp-type (as defined in ref. [49]) polarisation effect is a major factor that accounts for the strong activation provided by SO2CF3 groups. A most significant result is the finding that the 1,1-dimethoxy adduct 8d-Me is by far the most stable benzene s adduct so far reported. With a pKMeOH a value of 7.32, this adduct is formed exclusively through methanol addition up to pH10. This is onsistent with the location of 7d in the superelectrophilic region defined by pKMeOH a 9.5–10.5. For comparison, the solvent contribution is negligible in the formation of the 1,3-isomer 9d-Me, the pKMeOH a (10.59) of which is situated on the upper limit of the boundary. aking advantage of the simple relationship linking pKa values for s complexation in methanol and water, a ranking of the triflone 7d on the general thermodynamic scale constructed for Meisenheimer electrophiles in water is informative. An approximate calibration on the electrophilicity scale kinetically derived by Mayr et al. has also been made.
机译：在甲醇中，在T = 20 8C的较大pH范围2–13.70范围内，研究了2,4,6-三三氟甲磺酰基）苯甲醚（7d）络合的动力学。与在7d的未取代3位初始添加MeOe产生1,3-二甲氧基加合物（9d-Me）以及随后将该物质缓慢转化为1,1-二甲氧基异构体相关的两个竞争过程已确定8d-Me）。两种加合物8d-Me和9d-Me的稳定性比相关的2,4,6-三硝基苯甲醚（7a）的相关加合物8a-Me和9a-Me稳定，后者是Meisenheimer复杂化学中的常规参比芳香亲电试剂。已显示8d-Me和9d-Me的高稳定性源于比先前确定的8a-Me和9a-Me更高的形成速率和更低的分解速率，从而强调了SO2CF3基团对苯环的活化特别高（s）。苯甲醚系列2,4,6-trisACHTUNGTRENUNG（SO2CF3）-，2,6-6-bisACHTUNGTRENUNG（SO2CF3）-4-硝基-，4-SO2CF3-2,6-dinitro的络合物收集速率和平衡数据分析-和2,4,6-三硝基-支持这样的想法，即通过Fp型（定义见参考文献[49]）极化作用，加合物负电荷的共振稳定能力特别高，这是导致解释了SO2CF3组提供的强大激活。最重要的结果是发现1,1-二甲氧基加合物8d-Me是迄今为止报道的最稳定的苯s加合物。在pKMeOH值为7.32的情况下，该加合物仅通过添加至pH10的甲醇而形成。这与在pKMeOH a 9.5–10.5定义的超亲电区域中7d的位置一致。为了进行比较，在形成1，3-异构体9d-Me（其pKMeOH a（10.59）位于边界的上限）时，溶剂的贡献可忽略不计。利用将pKa值与甲醇和水中的络合物连接起来的简单关系，利用在水中为Meisenheimer亲电试剂构建的一般热力学规模对Triflone 7d进行排序具有参考价值。 Mayr等人在动力学上推导的亲电子尺度的近似校准。也取得了。

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