Enhancing the catalytic activity of hydronium ions through constrained environments

Yuanshuai Liu; Aleksei Vjunov; Hui Shi; Sebastian Eckstein; Donald M. Camaioni; Donghai Mei; Eszter Barath; Johannes A. Lercher

doi:10.1038/ncomms14113

Enhancing the catalytic activity of hydronium ions through constrained environments

Yuanshuai Liu, Aleksei Vjunov, Hui Shi, Sebastian Eckstein, Donald M. Camaioni, Donghai Mei, Eszter Barath, Johannes A. Lercher

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Abstract

The dehydration of alcohols is involved in many organic conversions but has to overcome high free-energy barriers in water. Here we demonstrate that hydronium ions confined in the nanopores of zeolite HBEA catalyse aqueous phase dehydration of cyclohexanol at a rate significantly higher than hydronium ions in water. This rate enhancement is not related to a shift in mechanism; for both cases, the dehydration of cyclohexanol occurs via an E1 mechanism with the cleavage of Cβ–H bond being rate determining. The higher activity of hydronium ions in zeolites is caused by the enhanced association between the hydronium ion and the alcohol, as well as a higher intrinsic rate constant in the constrained environments compared with water. The higher rate constant is caused by a greater entropy of activation rather than a lower enthalpy of activation. These insights should allow us to understand and predict similar processes in confined spaces.

Original language	English
Article number	14113
Journal	Nature Communications
Volume	8
DOIs	https://doi.org/10.1038/ncomms14113
Publication status	Published - 2 Mar 2017
Externally published	Yes

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title = "Enhancing the catalytic activity of hydronium ions through constrained environments",

abstract = "The dehydration of alcohols is involved in many organic conversions but has to overcome high free-energy barriers in water. Here we demonstrate that hydronium ions confined in the nanopores of zeolite HBEA catalyse aqueous phase dehydration of cyclohexanol at a rate significantly higher than hydronium ions in water. This rate enhancement is not related to a shift in mechanism; for both cases, the dehydration of cyclohexanol occurs via an E1 mechanism with the cleavage of Cβ–H bond being rate determining. The higher activity of hydronium ions in zeolites is caused by the enhanced association between the hydronium ion and the alcohol, as well as a higher intrinsic rate constant in the constrained environments compared with water. The higher rate constant is caused by a greater entropy of activation rather than a lower enthalpy of activation. These insights should allow us to understand and predict similar processes in confined spaces.",

author = "Yuanshuai Liu and Aleksei Vjunov and Hui Shi and Sebastian Eckstein and Camaioni, {Donald M.} and Donghai Mei and Eszter Barath and Lercher, {Johannes A.}",

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T1 - Enhancing the catalytic activity of hydronium ions through constrained environments

AU - Liu, Yuanshuai

AU - Vjunov, Aleksei

AU - Shi, Hui

AU - Eckstein, Sebastian

AU - Camaioni, Donald M.

AU - Mei, Donghai

AU - Barath, Eszter

AU - Lercher, Johannes A.

PY - 2017/3/2

Y1 - 2017/3/2

N2 - The dehydration of alcohols is involved in many organic conversions but has to overcome high free-energy barriers in water. Here we demonstrate that hydronium ions confined in the nanopores of zeolite HBEA catalyse aqueous phase dehydration of cyclohexanol at a rate significantly higher than hydronium ions in water. This rate enhancement is not related to a shift in mechanism; for both cases, the dehydration of cyclohexanol occurs via an E1 mechanism with the cleavage of Cβ–H bond being rate determining. The higher activity of hydronium ions in zeolites is caused by the enhanced association between the hydronium ion and the alcohol, as well as a higher intrinsic rate constant in the constrained environments compared with water. The higher rate constant is caused by a greater entropy of activation rather than a lower enthalpy of activation. These insights should allow us to understand and predict similar processes in confined spaces.

AB - The dehydration of alcohols is involved in many organic conversions but has to overcome high free-energy barriers in water. Here we demonstrate that hydronium ions confined in the nanopores of zeolite HBEA catalyse aqueous phase dehydration of cyclohexanol at a rate significantly higher than hydronium ions in water. This rate enhancement is not related to a shift in mechanism; for both cases, the dehydration of cyclohexanol occurs via an E1 mechanism with the cleavage of Cβ–H bond being rate determining. The higher activity of hydronium ions in zeolites is caused by the enhanced association between the hydronium ion and the alcohol, as well as a higher intrinsic rate constant in the constrained environments compared with water. The higher rate constant is caused by a greater entropy of activation rather than a lower enthalpy of activation. These insights should allow us to understand and predict similar processes in confined spaces.

U2 - 10.1038/ncomms14113

DO - 10.1038/ncomms14113

M3 - Article

SN - 2041-1723

VL - 8

JO - Nature Communications

JF - Nature Communications

M1 - 14113

ER -

Enhancing the catalytic activity of hydronium ions through constrained environments

Abstract

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