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Mechanistic investigations on Pinnick oxidation: a density functional theory study

Mechanistic investigations on Pinnick oxidation: a density functional theory study
Mechanistic investigations on Pinnick oxidation: a density functional theory study
A computational study on Pinnick oxidation of aldehydes into carboxylic acids using density functional theory (DFT) calculations has been evaluated with the (SMD)-M06-2X/aug-pVDZ level of theory, leading to an important understanding of the reaction mechanism that agrees with the experimental observations and explaining the substantial role of acid in driving the reaction. The DFT results elucidated that the first reaction step (FRS) proceeds in a manner where chlorous acid reacts with the aldehyde group through a distorted six-membered ring transition state to give a hydroxyallyl chlorite intermediate that undergoes a pericyclic fragmentation to release the carboxylic acid as a second reaction step (SRS). 1H NMR experiments and simulations showed that hydrogen bonding between carbonyl and t-butanol is unlikely to occur. Additionally, it was found that the FRS is a rate-determining and thermoneutral step, whereas SRS is highly exergonic with a low energetic barrier due to the Cl(III) → Cl(II) reduction. Frontier molecular orbital analysis, intrinsic reaction coordinate, molecular dynamics and distortion/interaction analysis further supported the proposed mechanism.
Density functional theory simulations, Molecular dynamics, Molecular orbital theory, Oxidation, Pinnick oxidation, Transition state
2054-5703
191568
Hussein, Aqeel
c6645ce9-c288-4b21-8af4-6f481b600bf1
Al-Hadedi, Azzam A.M.
84c4d61e-3c6f-43e4-a43c-534f54a716eb
Mahrath, Alaa J.
6037464a-c1e7-45f6-9dc6-1ab29d962603
Moustafa, Gamal
1a452cdc-4856-4243-9864-b391fb115f07
Almalki, Faisal A.
41dd76fa-3ebe-4182-be58-fa4ec85f9d34
Alqahtani, Alaa M.
53bd81c9-2b3f-4ead-8500-99e603766ab4
Shityakov, Sergey
f9d8d8ae-c594-4fcc-a29b-442e0e3e908e
Algazalli, Moaed E.
5a0c71bd-54fd-4d12-b23f-fe93c595c4ce
Hussein, Aqeel
c6645ce9-c288-4b21-8af4-6f481b600bf1
Al-Hadedi, Azzam A.M.
84c4d61e-3c6f-43e4-a43c-534f54a716eb
Mahrath, Alaa J.
6037464a-c1e7-45f6-9dc6-1ab29d962603
Moustafa, Gamal
1a452cdc-4856-4243-9864-b391fb115f07
Almalki, Faisal A.
41dd76fa-3ebe-4182-be58-fa4ec85f9d34
Alqahtani, Alaa M.
53bd81c9-2b3f-4ead-8500-99e603766ab4
Shityakov, Sergey
f9d8d8ae-c594-4fcc-a29b-442e0e3e908e
Algazalli, Moaed E.
5a0c71bd-54fd-4d12-b23f-fe93c595c4ce

Hussein, Aqeel, Al-Hadedi, Azzam A.M., Mahrath, Alaa J., Moustafa, Gamal, Almalki, Faisal A., Alqahtani, Alaa M., Shityakov, Sergey and Algazalli, Moaed E. (2020) Mechanistic investigations on Pinnick oxidation: a density functional theory study. Royal Society Open Science, 7 (2), 191568, [191568]. (doi:10.1098/rsos.191568).

Record type: Article

Abstract

A computational study on Pinnick oxidation of aldehydes into carboxylic acids using density functional theory (DFT) calculations has been evaluated with the (SMD)-M06-2X/aug-pVDZ level of theory, leading to an important understanding of the reaction mechanism that agrees with the experimental observations and explaining the substantial role of acid in driving the reaction. The DFT results elucidated that the first reaction step (FRS) proceeds in a manner where chlorous acid reacts with the aldehyde group through a distorted six-membered ring transition state to give a hydroxyallyl chlorite intermediate that undergoes a pericyclic fragmentation to release the carboxylic acid as a second reaction step (SRS). 1H NMR experiments and simulations showed that hydrogen bonding between carbonyl and t-butanol is unlikely to occur. Additionally, it was found that the FRS is a rate-determining and thermoneutral step, whereas SRS is highly exergonic with a low energetic barrier due to the Cl(III) → Cl(II) reduction. Frontier molecular orbital analysis, intrinsic reaction coordinate, molecular dynamics and distortion/interaction analysis further supported the proposed mechanism.

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Accepted/In Press date: 13 January 2020
e-pub ahead of print date: 5 February 2020
Keywords: Density functional theory simulations, Molecular dynamics, Molecular orbital theory, Oxidation, Pinnick oxidation, Transition state

Identifiers

Local EPrints ID: 437853
URI: http://eprints.soton.ac.uk/id/eprint/437853
ISSN: 2054-5703
PURE UUID: 8129fdfb-6d10-4cf0-82f2-69d89b514b26

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Date deposited: 20 Feb 2020 17:30
Last modified: 03 Mar 2021 17:34

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Contributors

Author: Aqeel Hussein
Author: Azzam A.M. Al-Hadedi
Author: Alaa J. Mahrath
Author: Gamal Moustafa
Author: Faisal A. Almalki
Author: Alaa M. Alqahtani
Author: Sergey Shityakov
Author: Moaed E. Algazalli

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