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Mechanism of Hydrocarbon Functionalization by an Iodate/Chloride System: The Role of Ester Protection

Schwartz, Nichole A. and Boaz, Nicholas C. and Kalman, Steven E. and Zhuang, Thompson and Goldberg, Jonathan M. and Fu, Ross and Nielsen, Robert J. and Goddard, William A., III and Groves, John T. and Gunnoe, T. Brent (2018) Mechanism of Hydrocarbon Functionalization by an Iodate/Chloride System: The Role of Ester Protection. ACS Catalysis, 8 (4). pp. 3138-3149. ISSN 2155-5435. https://resolver.caltech.edu/CaltechAUTHORS:20180314-075021354

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Abstract

Mixtures of chloride and iodate salts for light alkane oxidation achieve >20% yield of methyl trifluoroacetate (TFA) from methane with >85% selectivity. The mechanism of this C–H oxygenation has been probed by examining adamantane as a model substrate. These recent results lend support to the involvement of free radicals. Comparative studies between radical chlorination and iodate/chloride functionalization of adamantane afford statistically identical 3°:2° selectivities (∼5.2:1) and kinetic isotope effects for C–H/C–D functionalization (k_H/k_D = 1.6(3), 1.52(3)). Alkane functionalization by iodate/chloride in HTFA is proposed to occur through H-atom abstraction by free radical species including Cl• to give alkyl radicals. Iodine, which forms by in situ reduction of iodate, traps alkyl radicals as alkyl iodides that are subsequently converted to alkyl esters in HTFA solvent. Importantly, the alkyl ester products (RTFA) are quite stable to further oxidation under the oxidizing conditions due to the protecting nature of the ester moiety.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/acscatal.7b04397DOIArticle
https://pubs.acs.org/doi/10.1021/acscatal.7b04397PublisherArticle
https://pubs.acs.org/doi/suppl/10.1021/acscatal.7b04397PublisherSupporting Information
ORCID:
AuthorORCID
Nielsen, Robert J.0000-0002-7962-0186
Goddard, William A., III0000-0003-0097-5716
Groves, John T.0000-0002-9944-5899
Gunnoe, T. Brent0000-0001-5714-3887
Additional Information:© 2018 American Chemical Society. Received: December 20, 2017; Revised: February 19, 2018; Publication Date (Web): March 13, 2018. This work was supported by the U.S. Department of Energy (USDOE), Office of Energy Efficiency and Renewable Energy (EERE), Advanced Manufacturing Office Next Generation R&D Projects, under contract no. DE-AC07-05ID14517. The authors declare no competing financial interest.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-AC07-05ID14517
Subject Keywords:methane, ethane, chloride, partial oxidation, functionalization, radical, iodate
Other Numbering System:
Other Numbering System NameOther Numbering System ID
WAG1275
Issue or Number:4
Record Number:CaltechAUTHORS:20180314-075021354
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180314-075021354
Official Citation:Mechanism of Hydrocarbon Functionalization by an Iodate/Chloride System: The Role of Ester Protection. Nichole A. Schwartz, Nicholas C. Boaz, Steven E. Kalman, Thompson Zhuang, Jonathan M. Goldberg, Ross Fu, Robert J. Nielsen, William A. Goddard, III, John T. Groves, and T. Brent Gunnoe. ACS Catalysis 2018 8 (4), 3138-3149. DOI: 10.1021/acscatal.7b04397
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85300
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:15 Mar 2018 03:24
Last Modified:03 Oct 2019 19:29

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