Using molecular oxygen and Fe-N/C heterogeneous catalysts to achieve Mukaiyama epoxidations via in situ produced organic peroxy acids and acylperoxy radicals
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Author(s)
Type
Journal Article
Abstract
Under mild conditions of room temperature and pressure, and using either pure oxygen or air, aldehydes are converted using a heterogeneous Fe–N/C catalyst to produce the corresponding organic peroxy acid and acylperoxy radicals, which forms the epoxide from cyclohexene with high yield (91% for isobutyraldehyde in O2). Real-time monitoring of the rate of oxygen consumption and the electrochemical potential of the Fe–N/C catalyst has been used to study the formation of the peroxy acid and subsequent catalytic epoxidation of cyclohexene. Using isobutyraldehyde, it is shown that the aldehyde and the iron-based carbon catalyst (Fe–N/C) are involved in the rate determining step. Addition of a radical scavenger increases the induction time showing that radicals are initiated by the reaction between the aldehyde and the catalyst. Furthermore, UV-vis spectroscopy with 2,2′-azino-di-(3-ethylbenzthiazoline sulfonic acid) (ABTS) proved the in situ formation of peroxy acid. In the presence of cyclohexene, the peroxy acid leads to the corresponding epoxide with high yield. Monitoring the open circuit potential (OCP) and oxygen flow concurrently follows the production of the peroxy acid. The epoxidation reaction can take place only when the increase in open circuit potential is greater than 0.14 V, suggesting an in situ direct link between the relative oxidative strength of the peroxy acid and the likelihood of epoxidation.
Date Issued
2022-03-24
Date Acceptance
2022-03-24
Citation
Catalysis Science & Technology, 2022, 12 (9), pp.2978-2989
ISSN
2044-4753
Publisher
Royal Society of Chemistry
Start Page
2978
End Page
2989
Journal / Book Title
Catalysis Science & Technology
Volume
12
Issue
9
Copyright Statement
© The Royal Society of Chemistry 2022. This article is licensed under aCreative Commons Attribution 3.0 Unported Licence (https://creativecommons.org/licenses/by/3.0/)
License URL
Sponsor
Engineering & Physical Science Research Council (E
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000776143400001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
EP/P024807/1
Subjects
Science & Technology
Physical Sciences
Chemistry, Physical
Chemistry
HYDROGEN-PEROXIDE
ENANTIOSELECTIVE EPOXIDATION
OLEFIN EPOXIDATION
ALLYLIC OXIDATION
ALKENES
ACETONITRILE
CYCLOHEXENE
COMPLEX
COBALT(II)
REDUCTION
Publication Status
Published
Date Publish Online
2022-03-24