DFT Mechanistic Study of Methane Mono-Esterification by Hypervalent Iodine Alkane Oxidation Process
Abstract
Recent experiments report high yield (up to 40%) and selectivity (generally > 85%) for the direct partial oxidation of methane to methyl trifluoroacetate in trifluoroacetic acid solvent using hypervalent iodine as the oxidant and in the presence of substoichiometric amounts of chloride anion. We develop here the reaction mechanism for these results based on density functional theory calculations (at the M06-2X/6-311G**++/aug-pVTZ-PP level) of plausible intermediates and transition states. We find a mechanistic process that explains both reactivity as well as selectivity of the system. In this oxy-esterification (OxE) system, IO_2Cl_2– and/or IOCl_4– act as key transient intermediates, leading to the generation of the high-energy radicals IO2• and Cl• that mediate methane C–H bond cleavage. These studies suggest new experiments to validate the OxE mechanism.
Additional Information
© 2019 American Chemical Society. Received: May 4, 2019; Revised: May 25, 2019; Published: May 28, 2019. Author Contributions: All calculations were carried out by R.F., with strategies suggested by R.F., R.J.N., and W.A.G. Experimental work was carried out by NSL under mentorship by T.B.G. Critical guidance was provided by J.T.G. and T.B.G. The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. This research was sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office, under contract DE-AC05-00OR22725 with UT-Battelle, LLC. The funding for this computational project came from various gifts to the Materials and Process Simulation Center (MSC) at Caltech. The computers used were funded from DURIP grants to the MSC. The authors declare no competing financial interest.Attached Files
Supplemental Material - jp9b04239_si_001.pdf
Supplemental Material - jp9b04239_si_002.xlsx
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Additional details
- Eprint ID
- 95813
- DOI
- 10.1021/acs.jpcc.9b04239
- Resolver ID
- CaltechAUTHORS:20190528-110238542
- Department of Energy (DOE)
- DE-AC05-00OR22725
- Office of Naval Research (ONR)
- Army Research Office (ARO)
- Created
-
2019-05-28Created from EPrint's datestamp field
- Updated
-
2021-11-16Created from EPrint's last_modified field
- Other Numbering System Name
- WAG
- Other Numbering System Identifier
- 1340