Issue 2, 2020

Strong Lewis acidic catalysts for C–F bond activation by fluorination of activated γ-Al2O3

Abstract

A strong solid Lewis acid catalyst has been successfully obtained by modifying a known procedure of fluorinating γ-aluminium oxide, which was pre-calcined under vacuum. Calcination under vacuum at 700 °C followed by gas phase fluorination with CHClF2 led to various high-surface area materials. The structure and morphology of the catalysts was studied by P-XRD, N2 physisorption and MAS NMR spectroscopy. Their acidic sites were characterized by CD3CN adsorption and DRIFT spectroscopy as well as NH3 TPD measurements. The catalysts exhibit a moderate number of acidic sites, which however possess a very strong Lewis acidic character, and are remarkably active in catalysis, when compared to other fluorinated alumina phases known. They mediate in the presence of a silane with 1-fluoropentane dehydrofluorination reactions, isomerize 1,2-dibromohexafluoropropane and promote dismutation of CHClF2 at room temperature. This outstanding reactivity classifies these novel catalysts as strong solid Lewis acids, comparable with aluminium chlorofluoride or high-surface aluminium fluoride.

Graphical abstract: Strong Lewis acidic catalysts for C–F bond activation by fluorination of activated γ-Al2O3

Supplementary files

Article information

Article type
Paper
Submitted
07 8 2019
Accepted
07 12 2019
First published
09 12 2019

Catal. Sci. Technol., 2020,10, 391-402

Strong Lewis acidic catalysts for C–F bond activation by fluorination of activated γ-Al2O3

C. P. Marshall, G. Scholz, T. Braun and E. Kemnitz, Catal. Sci. Technol., 2020, 10, 391 DOI: 10.1039/C9CY01585J

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