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Computational investigation into the mechanistic features of bromide-catalyzed alcohol oxidation by PhIO in water

Citation

Farshadfar, K and Bird, MJ and Olivier, WJ and Hyland, CJT and Smith, JA and Ariafard, A, Computational investigation into the mechanistic features of bromide-catalyzed alcohol oxidation by PhIO in water, Journal of Organic Chemistry, 86, (3) pp. 2998-3007. ISSN 0022-3263 (2021) [Refereed Article]

Copyright Statement

Copyright 2021 American Chemical Society

DOI: doi:10.1021/acs.joc.0c02903

Abstract

Iodosobenzene (PhIO) is known to be a potent oxidant for alcohols in the presence of catalytic bromide in water. In order to understand this important and practical oxidation process, we have conducted density functional theory studies to shed light on the reaction mechanism. The key finding of this study is that PhIO is not the reactive oxidant itself. Instead, the active oxidant is hypobromite (BrO-), which is generated by the reaction of PhIO with bromide through an SN2-type reaction. Critically, water acts as a cocatalyst in the generation of BrO- through lowering the activation energy of this process. This investigation also demonstrates why BrO- is a more powerful oxidant than PhIO in the oxidation of alcohols. Other halide additives have been reported experimentally to be less effective catalysts than bromide - our calculations provide a clear rationale for these observations. We also examined the effect of replacing water with methanol on the ease of the SN2 reaction, finding that the replacement resulted in a higher activation barrier for the generation of BrO-. Overall, this work demonstrates that the hypervalent iodine(III) reagent PhIO can act as a convenient and controlled precursor of the oxidant hypobromite if the right conditions are present.

Item Details

Item Type:Refereed Article
Keywords:mechanisms, oxidation, iodosobenzene
Research Division:Chemical Sciences
Research Group:Organic chemistry
Research Field:Organic chemical synthesis
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the chemical sciences
UTAS Author:Olivier, WJ (Mr Wesley Olivier)
UTAS Author:Smith, JA (Associate Professor Jason Smith)
UTAS Author:Ariafard, A (Associate Professor Alireza Ariafard)
ID Code:143964
Year Published:2021
Web of Science® Times Cited:1
Deposited By:Chemistry
Deposited On:2021-04-12
Last Modified:2021-11-16
Downloads:0

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