ELECTROPHILIC AROMATIC SUBSTITUTION .6. PROTODESILYLATION AND PROTODETRITIATION OF SOME OXYGEN-CONTAINING AND SULPHUR-CONTAINING AROMATIC COMPOUNDS AND OF DIPHENYLMETHANE - EVIDENCE FOR HYPERCONJUGATION
ELECTROPHILIC AROMATIC SUBSTITUTION .6. PROTODESILYLATION AND PROTODETRITIATION OF SOME OXYGEN-CONTAINING AND SULPHUR-CONTAINING AROMATIC COMPOUNDS AND OF DIPHENYLMETHANE - EVIDENCE FOR HYPERCONJUGATION
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DOI：
10.1039/j29710001446
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发表时间：
1971-01-01
期刊：
影响因子：
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通讯作者：
TAYLOR, R
中科院分区：
文献类型：
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作者：
BAILEY, FP;TAYLOR, R
在50 °C甲醇-高氯酸溶液中，测定了某些芳香族化合物Me_3Si·C_6H_4X的脱硅反应的偏速率因子：（X =）2-OH，3720; 2-SH，4.42; 4-SH，11.3; 2-SMe，18.4; 4-SMe，65.2; 2-CH 2 Ph，3·75，以及在70 °C下在三氟乙酸中对茴香硫醚的2-位的还原，21，500。茴香硫醚和苯硫酚的相对反应性为诱导顺序，即，与氧和碳类似物的结果相反，SMe比SH激活更多，这被解释为构成后者化合物中超共轭的令人印象深刻的证据。邻位：帕拉比沿着系列CH 2 Y、OY、SY、Y、（其中Y = H、Me或Ph）和ZMe、ZH、ZPh（其中Z = CH_2，O，或S），这显然是由于邻位诱导效应的重要性增加所致;证实了先前观察到的二苯硫醚2位在脱硅基反应中的低反应活性，并表明这不是反常的。认为1270的Me 4 MeO的值比文献值1520更准确。二苯基硫醚的甲基化产生邻位和间位衍生物的混合物，而不仅仅是文献中所述的前者，这与最近关于噻吩乙醚的甲基化的报道相似。报道的4-LiC 6 H4·S·SiMe 3重排为4-SiMe 3·C6 H4·SLi几乎肯定是分子间反应。
Partial rate factors for protodesilylation of some aromatic compounds Me3Si·C6H4X in methanol–perchloric acid at 50 °C have been determined as: (X =)2-OH, 3720; 2-SH, 4·42; 4-SH, 11·3; 2-SMe, 18·4; 4-SMe, 65·2; 2-CH2Ph, 3·75, and for detritiation of the 2-position of thioanisole in trifluoroacetic acid at 70 °C, 21,500. The relative reactivity of thioanisole and thiophenol is in the inductive order, i.e., SMe activates more than SH in contrast to the results for the oxygen and carbon analogues and this is interpreted as constituting impressive evidence for hyperconjugation in the latter compounds. The ortho:para ratio decreases along the series CH2Y, OY, SY, (where Y = H, Me, or Ph) and ZMe, ZH, ZPh (where Z = CH2, O, or S) apparently through the increasing importance of the inductive effect at the ortho-position; the previously observed low reactivity of the 2-position of diphenyl sulphide in protodesilylation is confirmed and shown not to be anomalous.Application of the Yukawa–Tsuno equation to the desilylation data yields a value for σ+4-SH of –0·365; a value for ƒ4MeO of 1270 is argued to be more accurate than the literature value of 1520.Metallation of diphenyl sulphide produces a mixture of ortho- and meta-derivatives, not merely the former as stated in the literature, and this parallels a recent report on metallation of thiophenetole. The reported rearrangement of 4-LiC6H4·S·SiMe3 to 4-SiMe3·C6H4·SLi is shown to be almost certainly an intermolecular reaction.