HYDROCARBO ACIDITY AND METALATION
HYDROCARBO ACIDITY AND METALATION
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DOI：
10.1021/jo01113a005
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发表时间：
1956-01-01
影响因子：
3.6
通讯作者：
CLAFF, CE
中科院分区：
文献类型：
--
作者：
MORTON, AA;CLAFF, CE
用氢置换进行金属化的一个合理规则是，最强的酸应该形成盐。以前的论文2强调了这一原则，并在此基础上解释了大量的过程。其中包括丁基锂与溴代二苯砜的反应，甲苯、二甲苯、二甲苯和枯烯被戊基钠、5· 6· 7乙基钾8或钾-钠氧化物的金属化反应的易变性普遍降低，三苯基膦的反应性降低。甲烷、二苯甲烷和甲苯对钾或钠的反应性，10许多烃与钾-钠氧化物的反应性的一般变化，9特别是在从对伞花烃置换氢时甲基优于异丙基。[9]然而，这条规则并不是一成不变的。在固体表面和离子聚集体上的反应中，其它因素（可能是空间因素）有时会超过酸度的影响。人们已经知道，异丙基苯被戊基钠5· 6和被氧化钾钠9金属化的位置不同，它们的酸性不可能相同。芴的氢氧化钾金属化11出现在
A rule which seems reasonable for metalation by hydrogen displacement is that the salt of the strong-est acid should form. A previous paper2 emphasized this principle, and a large number of processes have been interpreted on this basis. Among these are the reaction of butyllithium with bromodiphen-ylsulfones, 3· 4 the generally decreasing ease of meta-lation of toluene, ethylbenzene, xylenes, and cumene by amylsodium, 5· 6· 7 ethylpotassium8 or potas-sium-sodium oxide, 9 the decreasing reactivity of tri-pheny! methane, diphenylmethane, and toluene to-ward potassium or sodium, 10 the general variation in reactivity of numerous hydrocarbons with potassium-sodium oxide9 andespecially the preference of methyl over isopropyl in the displacement of hy-drogen from p-cymene. 9 However the rule is not followed invariably. In reactions upon solid sur-faces and by aggregates of ions, other factorsprobably steric, sometimes override the acidity in-fluence. Already the metalations of cumene by amylsodium5· 6 and by potassium-sodium oxide9 are known to take placeat different positions which cannot have identical acidities. The metalation of fluorene by potassium hydroxide11 appears out of