Issue 48, 2014

Highly regioselective hydride transfer, oxidative dehydrogenation, and hydrogen-atom abstraction in the thermal gas-phase chemistry of [Zn(OH)]+/C3H8

Abstract

The thermal reactions of [Zn(OH)]+ with C3H8 have been studied by means of gas-phase experiments and computational investigation. Two types of C–H bond activation are observed in the experiment, and pertinent mechanistic features include inter alia: (i) the metal center of [Zn(OH)]+ serves as active site in the hydride transfer to generate [i-C3H7]+ as major product, (ii) generally, a high regioselectivity is accompanied by remarkable chemoselectivity: for example, the activation of a methyl C–H bond results mainly in the formation of water and [Zn(C3,H7)]+. According to computational work, this ionic product corresponds to [HZn(CH3CH[double bond, length as m-dash]CH2)]+. Attack of the zinc center at a secondary C–H bond leads preferentially to hydride transfer, thus giving rise to the generation of [i-C3H7]+; (iii) upon oxidative dehydrogenation (ODH), liberation of CH3CH2[double bond, length as m-dash]CH2 occurs to produce [HZn(H2O)]+. Both, ODH as well as H2O loss proceed through the same intermediate which is characterized by the fact that a methylene hydrogen atom from the substrate is transferred to the zinc and one hydrogen atom from the methyl group to the OH group of [Zn(OH)]+. The combined experimental/computational gas-phase study of C–H bond activation by zinc hydroxide provides mechanistic insight into related zinc-catalyzed large-scale processes and identifies the crucial role that the Lewis-acid character of zinc plays.

Graphical abstract: Highly regioselective hydride transfer, oxidative dehydrogenation, and hydrogen-atom abstraction in the thermal gas-phase chemistry of [Zn(OH)]+/C3H8

Supplementary files

Article information

Article type
Paper
Submitted
16 May 2014
Accepted
10 Sep 2014
First published
12 Sep 2014
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2014,16, 26617-26623

Author version available

Highly regioselective hydride transfer, oxidative dehydrogenation, and hydrogen-atom abstraction in the thermal gas-phase chemistry of [Zn(OH)]+/C3H8

X. Wu, H. Zhao, J. Li, M. Schlangen and H. Schwarz, Phys. Chem. Chem. Phys., 2014, 16, 26617 DOI: 10.1039/C4CP02139H

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements