Internal return of carbon dioxide in decarboxylation: Catalysis of separation and12C/13C kinetic isotope effects

被引：0

作者：

Mundle, Scott O. C. ^{[1
]}

Rathgeber, Steven ^{[1
]}

Lacrampe-Couloume, Georges ^{[2
]}

Lollar, Barbara Sherwood ^{[1
,2
]}

Kluger, Ronald ^{[1
]}

机构：

[1] Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada

[2] Department of Geology, University of Toronto, Toronto, ON M5S 3H6, Canada

来源：

Journal of the American Chemical Society | 2009年 / 131卷 / 33期

关键词：

(Figure Presented) It has been proposed that the decarboxylation of mandelylthiamin; the adduct of benzoylformate and thiamin; is uniquely catalyzed by protonated pyridines through a preassociation mechanism in which proton transfer competes with the internal return of carbon dioxide. Application of this mechanism suggests that the observed primary 12C/13C kinetic isotope effect in the absence of catalyst is reduced in magnitude because diffusion of carbon dioxide is partially rate-determining. Where proton transfer blocks the internal return of carbon dioxide; the separation of carbon dioxide is facilitated; and the observed isotope effect increases toward the intrinsic value for carbon-carbon bond breaking. Headspace analysis of carbon dioxide formed over the course of the reaction shows that protonated pyridine increases the magnitude of the observed 12C/13C KIE; consistent with the proposed mechanism. © 2009 American Chemical Society;

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摘要：

Journal article (JA)

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页码：11638 / 11639