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Prudlik A, Mohebbati N, Hildebrandt L, Heck A, Nuhn L, Francke R. TEMPO-Modified Polymethacrylates as Mediators in Electrosynthesis: Influence of the Molecular Weight on Redox Properties and Electrocatalytic Activity. Chemistry 2023; 29:e202202730. [PMID: 36426862 DOI: 10.1002/chem.202202730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 11/13/2022] [Accepted: 11/25/2022] [Indexed: 11/27/2022]
Abstract
Homogeneous catalysts ("mediators") are frequently employed in organic electrosynthesis to control selectivity. Despite their advantages, they can have a negative influence on the overall energy and mass balance if used only once or recycled inefficiently. Polymediators are soluble redox-active polymers applicable as electrocatalysts, enabling recovery by dialysis or membrane filtration. Using anodic alcohol oxidation as an example, we have demonstrated that TEMPO-modified polymethacrylates (TPMA) can act as efficient and recyclable catalysts. In the present work, the influence of the molecular size on the redox properties and the catalytic activity was carefully elaborated using a series of TPMAs with well-defined molecular weight distributions. Cyclic voltammetry studies show that the polymer chain length has a pronounced impact on the key-properties. Together with preparative-scale electrolysis experiments, an optimum size range was identified for polymediator-guided sustainable reaction control.
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Affiliation(s)
- Adrian Prudlik
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany.,Institute of Chemistry, Rostock University, Albert-Einstein-Str. 3a, 18059, Rostock, Germany
| | - Nayereh Mohebbati
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany.,Institute of Chemistry, Rostock University, Albert-Einstein-Str. 3a, 18059, Rostock, Germany
| | - Laura Hildebrandt
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Alina Heck
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.,Chair of Macromolecular Chemistry, Faculty of Chemistry and Pharmacy, Julius-Maximilians-Universität Würzburg, Röntgenring 11, 97070, Würzburg, Germany
| | - Lutz Nuhn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.,Chair of Macromolecular Chemistry, Faculty of Chemistry and Pharmacy, Julius-Maximilians-Universität Würzburg, Röntgenring 11, 97070, Würzburg, Germany
| | - Robert Francke
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany.,Institute of Chemistry, Rostock University, Albert-Einstein-Str. 3a, 18059, Rostock, Germany
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Doll KM, Cermak SC. Selective Electrochemical Oxidation of Alcohols Catalyzed by Partially Biobased TEMPO Analogs**. ChemistrySelect 2022. [DOI: 10.1002/slct.202201736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kenneth M. Doll
- United States Department of Agriculture, Agricultural Research Service National Center for Agricultural Utilization Research, Bio-Oils Research Unit, 1815 N. University St, Peoria Illinois 61604 USA
| | - Steven C. Cermak
- United States Department of Agriculture, Agricultural Research Service National Center for Agricultural Utilization Research, Bio-Oils Research Unit, 1815 N. University St, Peoria Illinois 61604 USA
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Enders P, Májek M, Lam CM, Little D, Francke R. How to Harness Electrochemical Mediators for Photocatalysis – A Systematic Approach Using the Phenanthro[9,10‐d]imidazole Framework as a Test Case. ChemCatChem 2022. [DOI: 10.1002/cctc.202200830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Patrick Enders
- Leibniz Institute for Catalysis: Leibniz-Institut fur Katalyse eV Electrochemistry & Catalysis GERMANY
| | - Michal Májek
- Comenius University in Bratislava: Univerzita Komenskeho v Bratislave Institute of Chemistry SLOVAKIA
| | - Chiu Marco Lam
- University of California Santa Barbara Chemistry & Biochemistry UNITED STATES
| | - Daniel Little
- University of California Santa Barbara Chemistry & Biochemistry UNITED STATES
| | - Robert Francke
- Rostock University Institute of Chemistry Albert-Einstein-Str. 3a 18059 Rostock GERMANY
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Cembellín S, Batanero B. Organic Electrosynthesis Towards Sustainability: Fundamentals and Greener Methodologies. CHEM REC 2021; 21:2453-2471. [PMID: 33955158 DOI: 10.1002/tcr.202100128] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 04/19/2021] [Indexed: 12/20/2022]
Abstract
The adoption of new measures that preserve our environment, on which our survival depends, is a necessity. Electro-organic processes are sustainable per se, by producing the activation of a substrate by electron transfer at normal pressure and room temperature. In the recent years, a highly crescent number of works on organic electrosynthesis are available. Novel strategies at the electrode are being developed enabling the construction of a great variety of complex organic molecules. However, the possibility of being scaled-up is mandatory in terms of sustainability. Thus, some electrochemical methodologies have demonstrated to report the best results in reducing pollution and saving energy. In this personal account, these methods have been compiled, being organized as follows: • Direct discharge electrosynthesis • Paired electrochemical reactions. and • Organic transformations utilizing electrocatalysis (in absence of heavy metals). Selected protocols are herein presented and discussed with representative recent examples. Final perspectives and reflections are also considered.
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Affiliation(s)
- Sara Cembellín
- University of Alcala, Organic and Inorganic Chemistry Department (Organic area), Campus, km 33,6 A2, 28805, Alcalá de Henares, Madrid, Spain
| | - Belén Batanero
- University of Alcala, Organic and Inorganic Chemistry Department (Organic area), Campus, km 33,6 A2, 28805, Alcalá de Henares, Madrid, Spain.,Instituto de Investigación Química, "Andrés M. del Río" (IQAR) University of Alcala
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Xu HH, Song J, Xu HC. Electrochemical Difluoromethylation of Electron-Deficient Alkenes. CHEMSUSCHEM 2019; 12:3060-3063. [PMID: 30684294 DOI: 10.1002/cssc.201803058] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Indexed: 06/09/2023]
Abstract
Electrochemical 1,2-hydroxydifluoromethylation and C-H difluoromethylation of acrylamides were developed by using CF2 HSO2 NHNHBoc as the source of the CF2 H group. These electricity-powered oxidative alkene functionalization reactions do not need transition-metal catalysts or chemical oxidants. The reaction outcome, 1,2-difuntionalization or C-H functionalization, is determined by the substituents on the amide nitrogen atom of the acrylamides instead of by the reaction conditions.
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Affiliation(s)
- He-Huan Xu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P.R. China
| | - Jinshuai Song
- College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou, 450001, P.R. China
| | - Hai-Chao Xu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P.R. China
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Ahmed N, Khatoon S. Facile Electrochemical Intramolecular Amination of Urea-Tethered Terminal Alkenes for the Synthesis of Cyclic Ureas. ChemistryOpen 2018; 7:576-582. [PMID: 30083492 PMCID: PMC6070678 DOI: 10.1002/open.201800064] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 06/05/2018] [Indexed: 01/11/2023] Open
Abstract
Facile intramolecular amination of unactivated alkenes has been achieved by using electricity as a catalyst that helps to generate an intermediate and accelerates formation of cyclic ureas in high yields. Using this method, no metal catalysts were used. During electrolysis, a nitrogen radical was formed at the urea substrate that cyclised with the alkene and generated a terminal carbon radical which further formed a bond with the 2,2,6,6-tetramethylpiperidine-N-oxyl radical (TEMPO). This method of electrolysis not only gives cyclic ureas but also functionalises terminal unactivated alkenes. This method can be considered to be environmentally friendly given that it avoids the issues of toxicity or complicated metal ligands and could therefore be potentially employed in green chemistry.
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Affiliation(s)
- Nisar Ahmed
- School of ChemistryCardiff UniversityCardiffCF10 3ATUK
| | - Saira Khatoon
- School of ChemistryCardiff UniversityCardiffCF10 3ATUK
- Department of ChemistryQuaid-i-Azam UniversityIslamabad45320Pakistan
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Wang F, Rafiee M, Stahl SS. Electrochemical Functional-Group-Tolerant Shono-type Oxidation of Cyclic Carbamates Enabled by Aminoxyl Mediators. Angew Chem Int Ed Engl 2018; 57:6686-6690. [PMID: 29659129 PMCID: PMC6201259 DOI: 10.1002/anie.201803539] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 04/11/2018] [Indexed: 11/12/2022]
Abstract
An electrochemical method has been developed for α-oxygenations of cyclic carbamates by using a bicyclic aminoxyl as a mediator and water as the nucleophile. The mediated electrochemical process enables substrate oxygenation to proceed at a potential that is approximately 1 V lower than the redox potential of the carbamate substrate. This feature allows for functional-group compatibility that is inaccessible with conventional Shono oxidations, which proceed by direct electrochemical substrate oxidation. This reaction also represents the first α-functionalization of non-activated cyclic carbamates with oxoammonium oxidants.
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Affiliation(s)
- Fei Wang
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Mohammad Rafiee
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Shannon S Stahl
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
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Wang F, Rafiee M, Stahl SS. Electrochemical Functional‐Group‐Tolerant Shono‐type Oxidation of Cyclic Carbamates Enabled by Aminoxyl Mediators. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201803539] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Fei Wang
- Department of ChemistryUniversity of Wisconsin-Madison Madison WI 53706 USA
| | - Mohammad Rafiee
- Department of ChemistryUniversity of Wisconsin-Madison Madison WI 53706 USA
| | - Shannon S. Stahl
- Department of ChemistryUniversity of Wisconsin-Madison Madison WI 53706 USA
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