Friedel-Crafts chemistry
Friedel-Crafts chemistry
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DOI：
10.1002/chin.197628315
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发表时间：
1973-06
期刊：
影响因子：
--
通讯作者：
G. Olah;D. Donovan;Henry C. Lin
中科院分区：
文献类型：
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作者：
G. Olah;D. Donovan;Henry C. Lin
(5)2a或2b在其他溶剂中的表观生成。根据我们的假设，由S02C1F(5.6)中的CH3F-SbF5形成的物种(5.6)、1：1HF-SbF5(5.5)和整齐的SBF(5.5)形成的物种，以前被认为与S02(5.56)形成的物种相同，但肯定具有与1不同的结构。由于预料到读者不愿接受这种巧合，我们重新准备了CH3F-SbF5-SG2ClF的溶液。之前未确定的13C核磁共振化学位移为81.92ppm，来自Me4Si，实际上比在CH3p-SbF5-S02溶液中发现的化学位移((ME4$i)73.71，我们的值，或74.82b·7)高8.21ppm。我们发现S02C1F中四个非平衡卤离子的16个13C化学位移与它们在S02中的值在-0.64到+0.9的范围内，这表明溶剂效应不是造成这种差异的原因。8相应地，在S02C1F系统中存在与1不同的物种，可能是甲基化的S02C1F或最初提出的结构2a或2b之一。在添加S02时形成沉淀物很容易被解释为形成甲基化S02，1的不溶盐的反应，而2a或2b不应该产生沉淀物，因为根据先前的解释，它们在两种溶剂中都是可溶的。我们的结果表明，还可以发现其他亲核试剂与CH3F-SBFS-S02在硫磺上发生反应，然后在碳上与反应产物发生后排反应。结果还表明，甲基阳离子和伯阳离子不能在S02溶液中形成，因为它们与S02反应，而不是以前认为的与SbFe~-反应。提出了中间稳定的阳离子(伯丁基和叔丁基之间)与其SO2反应产物存在紧密平衡、温度相关的平衡的可能性。
(5) The Apparent Formation of 2a or 2b in Other Solvents. According to our hypothesis the species formed from CH3F-SbF5 in S02C1F (5.6), 1: 1 HF-SbF5 (5.5), and neat SbFs (5.5), previously assumedto be identical with that formed in S02 (5.56), must have structures different from 1. Anticipating that readers would be reluctant to ac-cept this coincidence, we have reprepared solutions of CH3F-SbF5-SG2ClF. The previously undetermined 13C NMR chemical shift, 81.92 ppm from Me4Si, is, in fact, 8.21 ppm from that found in CH3p-SbF5-S02 solutions ((Me4 $ i) 73.71, our value, or 74.82 b· 7). That solvent effects were not responsible for the difference is indicated by our finding that 16 13C chemical shifts in four nonequilibrating halonium ions in S02C1F were within the range—0.64 to+ 0.9 from their value in S02. 8 Accordingly, a species dif-ferent from 1, possibly methylated S02C1F or one of the originally proposed structures 2a or 2b, is present in the S02C1F system. The formation of a precipitate upon addition of S02 is readily interpreted as a reaction to form an insoluble salt of methylated S02, 1, whereas 2a or 2b should not have given a precipitate, since, according to the previous interpretation, they are soluble in both solvents. Our results suggest that other nucleophiles may be found to react with CH3F-SbFs-S02 at sulfur, followed by rear-rangement to products of reaction at carbon. The results also indicate that methyl and primary cations cannot be formed in S02 solutions because they react with S02, not with SbFe~ as previously thought. The possibility that cations of intermediate stability (between primary and tert-butyl) will exist in closely balanced, temperature dependent9 equilibria with their S02 reaction products is suggest-ed.