Mechanisms of Racemization of Camphene-8-C^(14)

Abstract

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).

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