Mechanisms of Racemization of Camphene-8-C^(14)
Mechanisms of Racemization of Camphene-8-C^(14)
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莰烯-8-C^(14)的外消旋化机理
DOI：
10.1021/ja01109a037
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发表时间：
1953
影响因子：
15
通讯作者：
J. A. Yancey
中科院分区：
文献类型：
--
作者：
John D. Roberts;J. A. Yancey
C^（14）示踪剂研究表明，在水合二氧化钛、丙酮酸或盐酸苯胺存在下，光学活性莰烯至少通过两种不同的机制发生外消旋。其中一种机制不引起camphene-8-C^（14）的同位素位置重排，可能涉及连续的氢化物和瓦格纳重排。这种机理在水合二氧化钛和盐酸苯胺中起主导作用。camphene-8-C^（14）与丙酮酸的外消旋反应伴随着广泛的同位素位置重排，并通过假设对映异构体“camphenonium”（camphene-hydro）阳离子通过甲基移位（Nametkin重排）相互转化而得到了很好的表述。
It has been shown by C^(14)-tracer studies that optically-active camphene racemizes by at least two different mechanisms in the presence of hydrated titanium dioxide, pyruvic acid or aniline hydrochloride. One of these mechanisms does not cause isotope-position rearrangement of camphene-8-C^(14) and probably involves successive hydride and Wagner rearrangements. This mechanism predominates with hydrated titanium dioxide and aniline hydrochloride. Racemization of camphene-8-C^(14) with pyruvic acid is accompanied by extensive isotope-position rearrangement and is-well formulated by assuming interconversion of enantiomorphic "camphenonium" (camphene-hydro) cations through methyl group shifts (Nametkin rearrangements).