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Phuong J, Romero Z, Hasse H, Münnemann K. Polarization transfer methods for quantitative analysis of flowing mixtures with benchtop 13C NMR spectroscopy. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2024; 62:398-411. [PMID: 38114253 DOI: 10.1002/mrc.5417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 11/06/2023] [Accepted: 11/09/2023] [Indexed: 12/21/2023]
Abstract
Benchtop NMR spectroscopy is attractive for process monitoring; however, there are still drawbacks that often hamper its use, namely, the comparatively low spectral resolution in 1H NMR, as well as the low signal intensities and problems with the premagnetization of flowing samples in 13C NMR. We show here that all these problems can be overcome by using 1H-13C polarization transfer methods. Two ternary test mixtures (one with overlapping peaks in the 1H NMR spectrum and one with well-separated peaks, which was used as a reference) were studied with a 1 T benchtop NMR spectrometer using the polarization transfer sequence PENDANT (polarization enhancement that is nurtured during attached nucleus testing). The mixtures were analyzed quantitatively in stationary as well as in flow experiments by PENDANT enhanced 13C NMR experiments, and the results were compared with those from the gravimetric sample preparation and from standard 1H and 13C NMR spectroscopy. Furthermore, as a proxy for a process monitoring application, continuous dilution experiments were carried out, and the composition of the mixture was monitored in a flow setup by 13C NMR benchtop spectroscopy with PENDANT. The results demonstrate the high potential of polarization transfer methods for applications in quantitative process analysis with benchtop NMR instruments, in particular with flowing samples.
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Affiliation(s)
- Johnnie Phuong
- Laboratory of Engineering Thermodynamics (LTD), RPTU Kaiserslautern, Kaiserslautern, Germany
- Laboratory of Advanced Spin Engineering - Magnetic Resonance (LASE-MR), RPTU Kaiserslautern, Kaiserslautern, Germany
| | - Zeno Romero
- Laboratory of Engineering Thermodynamics (LTD), RPTU Kaiserslautern, Kaiserslautern, Germany
- Laboratory of Advanced Spin Engineering - Magnetic Resonance (LASE-MR), RPTU Kaiserslautern, Kaiserslautern, Germany
| | - Hans Hasse
- Laboratory of Engineering Thermodynamics (LTD), RPTU Kaiserslautern, Kaiserslautern, Germany
- Laboratory of Advanced Spin Engineering - Magnetic Resonance (LASE-MR), RPTU Kaiserslautern, Kaiserslautern, Germany
| | - Kerstin Münnemann
- Laboratory of Engineering Thermodynamics (LTD), RPTU Kaiserslautern, Kaiserslautern, Germany
- Laboratory of Advanced Spin Engineering - Magnetic Resonance (LASE-MR), RPTU Kaiserslautern, Kaiserslautern, Germany
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2
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Dyga M, Keller A, Hasse H. Distillation behavior of the system (formaldehyde + water + isoprenol). Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2022.118082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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3
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Kircher R, Mross S, Hasse H, Münnemann K. Functionalized Controlled Porous Glasses for Producing Radical-Free Hyperpolarized Liquids by Overhauser DNP. Molecules 2022; 27:molecules27196402. [PMID: 36234939 PMCID: PMC9572983 DOI: 10.3390/molecules27196402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 09/13/2022] [Accepted: 09/25/2022] [Indexed: 11/26/2022] Open
Abstract
Overhauser dynamic nuclear polarization (ODNP) can be used as a tool for NMR signal enhancement and happens on very short time scales. Therefore, ODNP is well suited for the measurement of fast-flowing samples, even in compact magnets, which is beneficial for the real-time monitoring of chemical reactions or processes. ODNP requires the presence of unpaired electrons in the sample, which is usually accomplished by the addition of stable radicals. However, radicals affect the nuclear relaxation times and can hamper the NMR detection. This is circumvented by immobilizing radicals in a packed bed allowing for the measurement of radical-free samples when using ex situ DNP techniques (DNP build-up and NMR detection happen at different places) and flow-induced separation of the hyperpolarized liquid from the radicals. Therefore, the synthesis of robust and chemically inert immobilized radical matrices is mandatory. In the present work, this is accomplished by immobilizing the radical glycidyloxy-tetramethylpiperidinyloxyl with a polyethyleneimine (PEI) linker on the surface of controlled porous glasses (CPG). Both the porosity of the CPGs and also the size of the PEI-linker were varied, resulting in a set of distinct radical matrices for continuous-flow ODNP. The study shows that CPGs with PEI-linkers provide robust, inert and efficient ODNP matrices.
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Meinhardt D, Schröder H, Hellwig J, Steimers E, Friebel A, Beweries T, Sawall M, von Harbou E, Neymeyr K. Model-based signal tracking in the quantitative analysis of time series of NMR spectra. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 339:107212. [PMID: 35398778 DOI: 10.1016/j.jmr.2022.107212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/28/2022] [Accepted: 03/29/2022] [Indexed: 06/14/2023]
Abstract
Hard modeling of NMR spectra by Gauss-Lorentz peak models is an effective way for dimensionality reduction. In this manner high-dimensional measured data are reduced to low-dimensional information as peak centers, amplitudes or peak widths. For time series of spectra these parameters can be assumed to be smooth functions in time. We suggest to model these time-dependent parameter functions by cubic spline functions, which makes a stable quantitative analysis of NMR series possible even for crossing, highly overlapping peaks. Applications are presented for the batch distillation of methanol and diethylamine, and the reaction of acetic anhydride with 2-propanol.
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Affiliation(s)
- Denise Meinhardt
- Universität Rostock, Institut für Mathematik, 18057 Rostock, Germany; Leibniz-Institut für Katalyse e.V., 18059 Rostock, Germany
| | - Henning Schröder
- Universität Rostock, Institut für Mathematik, 18057 Rostock, Germany; Leibniz-Institut für Katalyse e.V., 18059 Rostock, Germany
| | - Jan Hellwig
- Universität Rostock, Institut für Mathematik, 18057 Rostock, Germany; Leibniz-Institut für Katalyse e.V., 18059 Rostock, Germany
| | - Ellen Steimers
- Technische Universität Kaiserslautern, Laboratory of Engineering Thermodynamics (LTD), 67663 Kaiserslautern, Germany
| | - Anne Friebel
- Technische Universität Kaiserslautern, Laboratory of Engineering Thermodynamics (LTD), 67663 Kaiserslautern, Germany
| | | | - Mathias Sawall
- Universität Rostock, Institut für Mathematik, 18057 Rostock, Germany
| | - Erik von Harbou
- Technische Universität Kaiserslautern, Laboratory of Reaction and Fluid Process Engineering, 67663 Kaiserslautern, Germany
| | - Klaus Neymeyr
- Universität Rostock, Institut für Mathematik, 18057 Rostock, Germany; Leibniz-Institut für Katalyse e.V., 18059 Rostock, Germany.
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5
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Bornemann‐Pfeiffer M, Wolf J, Meyer K, Kern S, Angelone D, Leonov A, Cronin L, Emmerling F. Standardisierung und Kontrolle von Grignard‐Reaktionen mittels Online‐NMR in einer universellen chemischen Syntheseplattform. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202106323] [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)
- Martin Bornemann‐Pfeiffer
- Bundesanstalt für Materialforschung und -prüfung Richard-Willstätter-Straße 11 12489 Berlin Deutschland
- Chair of Chemical and Process Engineering Technische Universität Berlin Marchstr. 23 10587 Berlin Germany
| | - Jakob Wolf
- Bundesanstalt für Materialforschung und -prüfung Richard-Willstätter-Straße 11 12489 Berlin Deutschland
| | - Klas Meyer
- Bundesanstalt für Materialforschung und -prüfung Richard-Willstätter-Straße 11 12489 Berlin Deutschland
| | - Simon Kern
- S-PACT GmbH Burtscheiderstr. 1 52064 Aachen Deutschland
| | - Davide Angelone
- School of Chemistry University of Glasgow Glasgow G12 8QQ UK
| | - Artem Leonov
- School of Chemistry University of Glasgow Glasgow G12 8QQ UK
| | - Leroy Cronin
- School of Chemistry University of Glasgow Glasgow G12 8QQ UK
| | - Franziska Emmerling
- Bundesanstalt für Materialforschung und -prüfung Richard-Willstätter-Straße 11 12489 Berlin Deutschland
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Bornemann‐Pfeiffer M, Wolf J, Meyer K, Kern S, Angelone D, Leonov A, Cronin L, Emmerling F. Standardization and Control of Grignard Reactions in a Universal Chemical Synthesis Machine using online NMR. Angew Chem Int Ed Engl 2021; 60:23202-23206. [PMID: 34278673 PMCID: PMC8597166 DOI: 10.1002/anie.202106323] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Indexed: 11/17/2022]
Abstract
A big problem with the chemistry literature is that it is not standardized with respect to precise operational parameters, and real time corrections are hard to make without expert knowledge. This lack of context means difficult reproducibility because many steps are ambiguous, and hence depend on tacit knowledge. Here we present the integration of online NMR into an automated chemical synthesis machine (CSM aka. "Chemputer" which is capable of small-molecule synthesis using a universal programming language) to allow automated analysis and adjustment of reactions on the fly. The system was validated and benchmarked by using Grignard reactions which were chosen due to their importance in synthesis. The system was monitored in real time using online-NMR, and spectra were measured continuously during the reactions. This shows that the synthesis being done in the Chemputer can be dynamically controlled in response to feedback optimizing the reaction conditions according to the user requirements.
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Affiliation(s)
- Martin Bornemann‐Pfeiffer
- Department 1: Analytical Chemistry, Reference MaterialsBundesanstalt für Materialforschung und -prüfungRichard-Willstätter-Straße 1112489BerlinGermany
- Chair of Chemical and Process EngineeringTechnische Universität BerlinMarchstr. 2310587BerlinGermany
| | - Jakob Wolf
- Department 1: Analytical Chemistry, Reference MaterialsBundesanstalt für Materialforschung und -prüfungRichard-Willstätter-Straße 1112489BerlinGermany
| | - Klas Meyer
- Department 1: Analytical Chemistry, Reference MaterialsBundesanstalt für Materialforschung und -prüfungRichard-Willstätter-Straße 1112489BerlinGermany
| | - Simon Kern
- S-PACT GmbHBurtscheiderstr. 152064AachenGermany
| | | | - Artem Leonov
- School of ChemistryUniversity of GlasgowGlasgowG12 8QQUK
| | - Leroy Cronin
- School of ChemistryUniversity of GlasgowGlasgowG12 8QQUK
| | - Franziska Emmerling
- Department 1: Analytical Chemistry, Reference MaterialsBundesanstalt für Materialforschung und -prüfungRichard-Willstätter-Straße 1112489BerlinGermany
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Abstract
Benchtop nuclear magnetic resonance (NMR) spectroscopy uses small permanent magnets to generate magnetic fields and therefore offers the advantages of operational simplicity and reasonable cost, presenting a viable alternative to high-field NMR spectroscopy. In particular, the use of benchtop NMR spectroscopy for rapid in-field analysis, e.g., for quality control or forensic science purposes, has attracted considerable attention. As benchtop NMR spectrometers are sufficiently compact to be operated in a fume hood, they can be efficiently used for real-time reaction and process monitoring. This review introduces the recent applications of benchtop NMR spectroscopy in diverse fields, including food science, pharmaceuticals, process and reaction monitoring, metabolomics, and polymer materials.
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Saib A, Bara-Estaún A, Harper OJ, Berry DBG, Thomlinson IA, Broomfield-Tagg R, Lowe JP, Lyall CL, Hintermair U. Engineering aspects of FlowNMR spectroscopy setups for online analysis of solution-phase processes. REACT CHEM ENG 2021. [DOI: 10.1039/d1re00217a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In this article we review some fundamental engineering concepts and evaluate components and materials required to assemble and operate safe and effective FlowNMR setups that reliably generate meaningful results.
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Affiliation(s)
- Asad Saib
- Department of Chemistry, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Dynamic Reaction Monitoring Facility, University of Bath, Claverton Down, BA2 7AY Bath, UK
| | - Alejandro Bara-Estaún
- Department of Chemistry, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Dynamic Reaction Monitoring Facility, University of Bath, Claverton Down, BA2 7AY Bath, UK
| | - Owen J. Harper
- Department of Chemistry, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Dynamic Reaction Monitoring Facility, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Centre for Sustainable & Circular Technologies, University of Bath, Bath BA2 7AY, UK
| | - Daniel B. G. Berry
- Department of Chemistry, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Dynamic Reaction Monitoring Facility, University of Bath, Claverton Down, BA2 7AY Bath, UK
| | - Isabel A. Thomlinson
- Department of Chemistry, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Dynamic Reaction Monitoring Facility, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Centre for Sustainable & Circular Technologies, University of Bath, Bath BA2 7AY, UK
| | - Rachael Broomfield-Tagg
- Department of Chemistry, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Dynamic Reaction Monitoring Facility, University of Bath, Claverton Down, BA2 7AY Bath, UK
| | - John P. Lowe
- Department of Chemistry, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Dynamic Reaction Monitoring Facility, University of Bath, Claverton Down, BA2 7AY Bath, UK
| | - Catherine L. Lyall
- Department of Chemistry, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Dynamic Reaction Monitoring Facility, University of Bath, Claverton Down, BA2 7AY Bath, UK
| | - Ulrich Hintermair
- Department of Chemistry, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Dynamic Reaction Monitoring Facility, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Centre for Sustainable & Circular Technologies, University of Bath, Bath BA2 7AY, UK
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9
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Bornemann‐Pfeiffer M, Kern S, Maiwald M, Meyer K. Calibration‐Free Chemical Process and Quality Control Units as Enablers for Modular Production. CHEM-ING-TECH 2020. [DOI: 10.1002/cite.202000150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Martin Bornemann‐Pfeiffer
- Bundesanstalt für Materialforschung und -prüfung (BAM) Richard-Willstaetter-Straße 11 12489 Berlin Germany
- Technical University of Berlin Chemical and Process Engineering Fraunhoferstraße 33–36 10587 Berlin Germany
| | - Simon Kern
- Bundesanstalt für Materialforschung und -prüfung (BAM) Richard-Willstaetter-Straße 11 12489 Berlin Germany
- S-PACT GmbH Burtscheider Straße 1 52064 Aachen Germany
| | - Michael Maiwald
- Bundesanstalt für Materialforschung und -prüfung (BAM) Richard-Willstaetter-Straße 11 12489 Berlin Germany
| | - Klas Meyer
- Bundesanstalt für Materialforschung und -prüfung (BAM) Richard-Willstaetter-Straße 11 12489 Berlin Germany
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10
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Nestle N, Lim ZJ, Böhringer T, Abtmeyer S, Arenz S, Leinweber FC, Weiß T, von Harbou E. Taking compact NMR to monitoring real reactions in large-scale chemical industries-General considerations and learnings from a lab-scale test case. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2020; 58:1213-1221. [PMID: 32526070 DOI: 10.1002/mrc.5061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 06/03/2020] [Accepted: 06/04/2020] [Indexed: 06/11/2023]
Abstract
The considerations for use of compact nuclear magnetic resonance in a large-scale industrial environment clearly differ from those in academic and educational settings and even from those in smaller companies. In the first part of this article, these differences will be discussed along with the additional requirements that need to be fulfilled for successful applicability in different use cases. In the second part of the article, outcomes from different research activities aiming to fulfill these requirements will be presented with a focus on an online reaction-monitoring study on a lab-scale nucleophilic chlorination reaction.
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Affiliation(s)
- Nikolaus Nestle
- Material Physics and Analytics, BASF SE, Carl-Bosch-Straße, Ludwigshafen am Rhein, 67056, Germany
| | - Zi Jian Lim
- Center of Expertise for Process Analytical Technology, BASF SE, Carl-Bosch-Straße, Ludwigshafen am Rhein, 67056, Germany
| | - Tobias Böhringer
- Center of Expertise for Process Analytical Technology, BASF SE, Carl-Bosch-Straße, Ludwigshafen am Rhein, 67056, Germany
| | - Sarah Abtmeyer
- Center of Expertise for Process Analytical Technology, BASF SE, Carl-Bosch-Straße, Ludwigshafen am Rhein, 67056, Germany
| | - Sven Arenz
- Material Physics and Analytics, BASF SE, Carl-Bosch-Straße, Ludwigshafen am Rhein, 67056, Germany
| | - Felix C Leinweber
- Center of Expertise for Process Analytical Technology, BASF SE, Carl-Bosch-Straße, Ludwigshafen am Rhein, 67056, Germany
| | - Thomas Weiß
- Material Physics and Analytics, BASF SE, Carl-Bosch-Straße, Ludwigshafen am Rhein, 67056, Germany
| | - Erik von Harbou
- Process Research and Chemical Engineering, BASF SE, Carl-Bosch-Straße, Ludwigshafen am Rhein, 67056, Germany
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11
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Burueva DB, Eills J, Blanchard JW, Garcon A, Picazo‐Frutos R, Kovtunov KV, Koptyug IV, Budker D. Chemical Reaction Monitoring using Zero‐Field Nuclear Magnetic Resonance Enables Study of Heterogeneous Samples in Metal Containers. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Dudari B. Burueva
- Laboratory of Magnetic Resonance Microimaging International Tomography Center 630090 Novosibirsk Russia
- Novosibirsk State University 630090 Novosibirsk Russia
| | - James Eills
- Helmholtz Institute Mainz GSI Helmholtzzentrum für Schwerionenforschung GmbH 55128 Mainz Germany
- Johannes Gutenberg University 55090 Mainz Germany
| | - John W. Blanchard
- Helmholtz Institute Mainz GSI Helmholtzzentrum für Schwerionenforschung GmbH 55128 Mainz Germany
| | - Antoine Garcon
- Helmholtz Institute Mainz GSI Helmholtzzentrum für Schwerionenforschung GmbH 55128 Mainz Germany
- Johannes Gutenberg University 55090 Mainz Germany
| | - Román Picazo‐Frutos
- Helmholtz Institute Mainz GSI Helmholtzzentrum für Schwerionenforschung GmbH 55128 Mainz Germany
- Johannes Gutenberg University 55090 Mainz Germany
| | - Kirill V. Kovtunov
- Laboratory of Magnetic Resonance Microimaging International Tomography Center 630090 Novosibirsk Russia
- Novosibirsk State University 630090 Novosibirsk Russia
| | - Igor V. Koptyug
- Laboratory of Magnetic Resonance Microimaging International Tomography Center 630090 Novosibirsk Russia
- Novosibirsk State University 630090 Novosibirsk Russia
| | - Dmitry Budker
- Helmholtz Institute Mainz GSI Helmholtzzentrum für Schwerionenforschung GmbH 55128 Mainz Germany
- Johannes Gutenberg University 55090 Mainz Germany
- University of California Berkeley Berkeley CA 94720 USA
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12
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Burueva DB, Eills J, Blanchard JW, Garcon A, Picazo‐Frutos R, Kovtunov KV, Koptyug IV, Budker D. Chemical Reaction Monitoring using Zero-Field Nuclear Magnetic Resonance Enables Study of Heterogeneous Samples in Metal Containers. Angew Chem Int Ed Engl 2020; 59:17026-17032. [PMID: 32510813 PMCID: PMC7540358 DOI: 10.1002/anie.202006266] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Indexed: 12/28/2022]
Abstract
We demonstrate that heterogeneous/biphasic chemical reactions can be monitored with high spectroscopic resolution using zero-field nuclear magnetic resonance spectroscopy. This is possible because magnetic susceptibility broadening is negligible at ultralow magnetic fields. We show the two-step hydrogenation of dimethyl acetylenedicarboxylate with para-enriched hydrogen gas in conventional glass NMR tubes, as well as in a titanium tube. The low frequency zero-field NMR signals ensure that there is no significant signal attenuation arising from shielding by the electrically conductive sample container. This method paves the way for in situ monitoring of reactions in complex heterogeneous multiphase systems and in reactors made of conductive materials while maintaining resolution and chemical specificity.
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Affiliation(s)
- Dudari B. Burueva
- Laboratory of Magnetic Resonance MicroimagingInternational Tomography Center630090NovosibirskRussia
- Novosibirsk State University630090NovosibirskRussia
| | - James Eills
- Helmholtz Institute MainzGSI Helmholtzzentrum für Schwerionenforschung GmbH55128MainzGermany
- Johannes Gutenberg University55090MainzGermany
| | - John W. Blanchard
- Helmholtz Institute MainzGSI Helmholtzzentrum für Schwerionenforschung GmbH55128MainzGermany
| | - Antoine Garcon
- Helmholtz Institute MainzGSI Helmholtzzentrum für Schwerionenforschung GmbH55128MainzGermany
- Johannes Gutenberg University55090MainzGermany
| | - Román Picazo‐Frutos
- Helmholtz Institute MainzGSI Helmholtzzentrum für Schwerionenforschung GmbH55128MainzGermany
- Johannes Gutenberg University55090MainzGermany
| | - Kirill V. Kovtunov
- Laboratory of Magnetic Resonance MicroimagingInternational Tomography Center630090NovosibirskRussia
- Novosibirsk State University630090NovosibirskRussia
| | - Igor V. Koptyug
- Laboratory of Magnetic Resonance MicroimagingInternational Tomography Center630090NovosibirskRussia
- Novosibirsk State University630090NovosibirskRussia
| | - Dmitry Budker
- Helmholtz Institute MainzGSI Helmholtzzentrum für Schwerionenforschung GmbH55128MainzGermany
- Johannes Gutenberg University55090MainzGermany
- University of California BerkeleyBerkeleyCA94720USA
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