DFT Mechanistic Study of Methane Mono-Esterification by Hypervalent Iodine Alkane Oxidation Process

Ross Fu; Robert J. Nielsen; Nichole S. Liebov; William A. Goddard; T. Brent Gunnoe; John T. Groves

doi:10.1021/acs.jpcc.9b04239

DFT Mechanistic Study of Methane Mono-Esterification by Hypervalent Iodine Alkane Oxidation Process

Ross Fu, Robert J. Nielsen, Nichole S. Liebov, William A. Goddard, T. Brent Gunnoe, John T. Groves

Research output: Contribution to journal › Article › peer-review

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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, IO₂Cl₂^- and/or IOCl₄^- 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.

Original language	English (US)
Journal	Journal of Physical Chemistry C
DOIs	https://doi.org/10.1021/acs.jpcc.9b04239
State	Published - Jan 1 2019

All Science Journal Classification (ASJC) codes

Electronic, Optical and Magnetic Materials
Energy(all)
Physical and Theoretical Chemistry
Surfaces, Coatings and Films

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10.1021/acs.jpcc.9b04239

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title = "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, IO2Cl2- and/or IOCl4- 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.",

author = "Ross Fu and Nielsen, {Robert J.} and Liebov, {Nichole S.} and Goddard, {William A.} and Gunnoe, {T. Brent} and Groves, {John T.}",

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doi = "10.1021/acs.jpcc.9b04239",

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journal = "Journal of Physical Chemistry C",

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T1 - DFT Mechanistic Study of Methane Mono-Esterification by Hypervalent Iodine Alkane Oxidation Process

AU - Fu, Ross

AU - Nielsen, Robert J.

AU - Liebov, Nichole S.

AU - Goddard, William A.

AU - Gunnoe, T. Brent

AU - Groves, John T.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - 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, IO2Cl2- and/or IOCl4- 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.

AB - 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, IO2Cl2- and/or IOCl4- 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.

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DFT Mechanistic Study of Methane Mono-Esterification by Hypervalent Iodine Alkane Oxidation Process

Abstract

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