1
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Maschmeyer T, Russell DJ, Napolitano JG, Hein JE. Reaction monitoring via benchtop nuclear magnetic resonance spectroscopy: A practical comparison of on-line stopped-flow and continuous-flow sampling methods. Magn Reson Chem 2024; 62:310-322. [PMID: 37737536 DOI: 10.1002/mrc.5395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 08/28/2023] [Accepted: 08/30/2023] [Indexed: 09/23/2023]
Abstract
The ability for nuclear magnetic resonance (NMR) spectroscopy to provide quantitative, structurally rich information makes this spectroscopic technique an attractive reaction monitoring tool. The practicality of NMR for this type of analysis has only increased in the recent years with the influx of commercially available benchtop NMR instruments and compatible flow systems. In this study, we aim to compare 19F NMR reaction profiles acquired under both on-line continuous-flow and stopped-flow sampling methods, with modern benchtop NMR instrumentation, and two reaction systems: a homogeneous imination reaction and a biphasic activation of a carboxylic acid to acyl fluoride. Reaction trends with higher data density can be acquired with on-line continuous-flow analyses, and this work highlights that representative reaction trends can be acquired without any correction when monitoring resonances with a shorter spin-lattice relaxation time (T1), and with the used flow conditions. On-line stopped-flow analyses resulted in representative reaction trends in all cases, including the monitoring of resonances with a long T1, without the need of any correction factors. The benefit of easier data analysis, however, comes with the cost of time, as the fresh reaction solution must be flowed into the NMR system, halted, and time must be provided for spins to become polarized in the instrument's external magnetic field prior to spectral measurement. Results for one of the reactions were additionally compared with the use of a high-field NMR.
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Affiliation(s)
- Tristan Maschmeyer
- Department of Chemistry, The University of British Columbia, Vancouver, Canada
- Small Molecule Pharmaceutical Sciences, Genentech Inc., South San Francisco, California, USA
| | - David J Russell
- Small Molecule Pharmaceutical Sciences, Genentech Inc., South San Francisco, California, USA
| | - José G Napolitano
- Small Molecule Pharmaceutical Sciences, Genentech Inc., South San Francisco, California, USA
| | - Jason E Hein
- Department of Chemistry, The University of British Columbia, Vancouver, Canada
- Acceleration Consortium, University of Toronto, Toronto, Canada
- Department of Chemistry, University of Bergen, Bergen, Norway
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2
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Deckers C, Rehm TH. In situ Diazonium Salt Formation and Photochemical Aryl-Aryl Coupling in Continuous Flow Monitored by Inline NMR Spectroscopy. Chemistry 2024:e202303692. [PMID: 38462439 DOI: 10.1002/chem.202303692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 03/09/2024] [Accepted: 03/10/2024] [Indexed: 03/12/2024]
Abstract
A novel class of diazonium salts is introduced for the photochemical aryl-aryl coupling to produce (substituted) biphenyls. As common diazonium tetrafluoroborate salts fail, soluble and safe aryl diazonium trifluoroacetates are applied. In this mild synthesis route no catalysts are required to generate an aryl-radical by irradiation with UV-A light (365 nm). This reactive species undergoes direct C-H arylation at an arene, forming the product in reasonable reaction times. With the implementation of a continuous flow setup in a capillary photoreactor 13 different biphenyl derivatives are successfully synthesized. By integrating an inline 19F-NMR benchtop spectrometer, samples are reliably quantified as the fluorine-substituents act as a probe. Here, real-time NMR spectroscopy is a perfect tool to monitor the continuously operated system, which produces fine chemicals of industrial relevance even in a multigram scale.
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Affiliation(s)
- Christoph Deckers
- Division Chemistry, Sustainable Chemical Syntheses Group, Fraunhofer Institute for Microengineering and Microsystems IMM, Carl-Zeiss-Strasse 18-20, 55129, Mainz, Germany
- Johannes Gutenberg University Mainz, Department of Chemistry, Duesbergweg 10-14, 55128, Mainz, Germany
| | - Thomas H Rehm
- Division Chemistry, Sustainable Chemical Syntheses Group, Fraunhofer Institute for Microengineering and Microsystems IMM, Carl-Zeiss-Strasse 18-20, 55129, Mainz, Germany
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3
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Sanders MA, Chittari SS, Sherman N, Foley JR, Knight AS. Versatile Triphenylphosphine-Containing Polymeric Catalysts and Elucidation of Structure-Function Relationships. J Am Chem Soc 2023; 145:9686-9692. [PMID: 37079910 DOI: 10.1021/jacs.3c01092] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
Synthetic polymers are a modular solution to bridging the two most common classes of catalysts: proteins and small molecules. Polymers offer the synthetic versatility of small-molecule catalysts while simultaneously having the ability to construct microenvironments mimicking those of natural proteins. We synthesized a panel of polymeric catalysts containing a novel triphenylphosphine acrylamide monomer and investigated how their properties impact the rate of a model Suzuki-Miyaura cross-coupling reaction. Systematic variation of polymer properties, such as the molecular weight, functional density, and comonomer identity, led to tunable reaction rates and solvent compatibility, including full conversion in an aqueous medium. Studies with bulkier substrates revealed connections between polymer parameters and reaction conditions that were further elucidated with a regression analysis. Some connections were substrate-specific, highlighting the value of the rapidly tunable polymer catalyst. Collectively, these results aid in building structure-function relationships to guide the development of polymer catalysts with tunable substrates and environmental compatibility.
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Affiliation(s)
- Matthew A Sanders
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Supraja S Chittari
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Nicole Sherman
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Jack R Foley
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Abigail S Knight
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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4
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Wouters B, Miggiels P, Bezemer R, van der Cruijsen EA, van Leeuwen E, Gauvin J, Houben K, Babu Sai Sankar Gupta K, Zuijdwijk P, Harms A, Carvalho de Souza A, Hankemeier T. Automated Segmented-Flow Analysis – NMR with a Novel Fluoropolymer Flow Cell for High-Throughput Screening. Anal Chem 2022; 94:15350-15358. [DOI: 10.1021/acs.analchem.2c03038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bert Wouters
- Metabolomics and Analytics Centre, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CCLeiden, The Netherlands
| | - Paul Miggiels
- Metabolomics and Analytics Centre, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CCLeiden, The Netherlands
| | - Roland Bezemer
- DSM Biotechnology Center, Alexander Fleminglaan 1, 2613 AXDelft, The Netherlands
| | | | - Erik van Leeuwen
- DSM Biotechnology Center, Alexander Fleminglaan 1, 2613 AXDelft, The Netherlands
| | - John Gauvin
- DSM Biotechnology Center, Alexander Fleminglaan 1, 2613 AXDelft, The Netherlands
| | - Klaartje Houben
- DSM Biotechnology Center, Alexander Fleminglaan 1, 2613 AXDelft, The Netherlands
| | | | - Paul Zuijdwijk
- DSM Biotechnology Center, Alexander Fleminglaan 1, 2613 AXDelft, The Netherlands
| | - Amy Harms
- Metabolomics and Analytics Centre, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CCLeiden, The Netherlands
| | | | - Thomas Hankemeier
- Metabolomics and Analytics Centre, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CCLeiden, The Netherlands
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5
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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6
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Gouilleux B, Farjon J, Giraudeau P. Gradient-based pulse sequences for benchtop NMR spectroscopy. J Magn Reson 2020; 319:106810. [PMID: 33036709 DOI: 10.1016/j.jmr.2020.106810] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 08/12/2020] [Accepted: 08/13/2020] [Indexed: 06/11/2023]
Abstract
Benchtop NMR spectroscopy has been on the rise for the last decade, by bringing high-resolution NMR in environments that are not easily compatible with high-field NMR. Benchtop spectrometers are accessible, low cost and show an impressive performance in terms of sensitivity with respect to the relatively low associated magnetic field (40-100 MHz). However, their application is limited by the strong and ubiquitous peak overlaps arising from the complex mixtures which are often targeted, often characterized by a great diversity of concentrations and by strong signals from non-deuterated solvents. Such limitations can be addressed by pulse sequences making clever use of magnetic field gradient pulses, capable of performing efficient coherence selection or encoding chemical shift or diffusion information. Gradients pulses are well-known ingredients of high-field pulse sequence recipes, but were only recently made available on benchtop spectrometers, thanks to the introduction of gradient coils in 2015. This article reviews the recent methodological advances making use of gradient pulses on benchtop spectrometers and the applications stemming from these developments. Particular focus is made on solvent suppression schemes, diffusion-encoded, and spatially-encoded experiments, while discussing both methodological advances and subsequent applications. We eventually discuss the exciting development and application perspectives that result from such advances.
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Affiliation(s)
- Boris Gouilleux
- Université Paris-Saclay, ICMMO, UMR CNRS 8182, RMN en Milieu Orienté, France
| | - Jonathan Farjon
- Université de Nantes, CNRS, CEISAM UMR 6230, F-44000 Nantes, France
| | - Patrick Giraudeau
- Université de Nantes, CNRS, CEISAM UMR 6230, F-44000 Nantes, France.
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7
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Howe PWA. Recent developments in the use of fluorine NMR in synthesis and characterisation. Prog Nucl Magn Reson Spectrosc 2020; 118-119:1-9. [PMID: 32883447 DOI: 10.1016/j.pnmrs.2020.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/14/2020] [Accepted: 02/20/2020] [Indexed: 06/11/2023]
Abstract
A review of developments in fluorine NMR of relevance to synthesis, characterisation and industrial applications of small organic molecules. Developments considered include those in spectrometer technology, computational methods and pulse sequences. The review of 80 references outlines applications in areas of identification, quantitation, mixture analysis, reaction monitoring, environmental studies and fragment-based drug design.
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Affiliation(s)
- Peter W A Howe
- Syngenta, Jealott's Hill Research Centre, Bracknell, Berkshire RG42 6EY, UK.
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8
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Friebel A, Specht T, von Harbou E, Münnemann K, Hasse H. Prediction of flow effects in quantitative NMR measurements. J Magn Reson 2020; 312:106683. [PMID: 32014660 DOI: 10.1016/j.jmr.2020.106683] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 12/31/2019] [Accepted: 01/02/2020] [Indexed: 06/10/2023]
Abstract
A method for the prediction of the magnetization in flow NMR experiments is presented, which can be applied to mixtures. It enables a quantitative evaluation of NMR spectra of flowing liquid samples even in cases in which the magnetization is limited by the flow. A transport model of the nuclei's magnetization, which is based on the Bloch-equations, is introduced into a computational fluid dynamics (CFD) code. This code predicts the velocity field and relative magnetization of different nuclei for any chosen flow cell geometry, fluid and flow rate. The prediction of relative magnetization is used to correct the observed reduction of signal intensity caused by incomplete premagnetization in fast flowing liquids. By means of the model, quantitative NMR measurements at high flow rates are possible. The method is predictive and enables calculating correction factors for any flow cell design and operating condition based on simple static T1 time measurements. This makes time-consuming calibration measurements for assessing the influence of flow effects obsolete, which otherwise would have to be carried out for each studied condition. The new method is especially interesting for flow measurements with compact medium field NMR spectrometers, which have small premagnetization volumes. In the present work, experiments with three different flow cells in a medium field NMR spectrometer were carried out. Acetonitrile, water, and mixtures of these components were used as model fluids. The experimental results for the magnetization were compared to the predictions from the CFD model and good agreement was observed.
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Affiliation(s)
- Anne Friebel
- Laboratory of Engineering Thermodynamics (LTD), University of Kaiserslautern, Germany
| | - Thomas Specht
- Laboratory of Engineering Thermodynamics (LTD), University of Kaiserslautern, Germany
| | - Erik von Harbou
- Laboratory of Engineering Thermodynamics (LTD), University of Kaiserslautern, Germany.
| | - Kerstin Münnemann
- Laboratory of Engineering Thermodynamics (LTD), University of Kaiserslautern, Germany
| | - Hans Hasse
- Laboratory of Engineering Thermodynamics (LTD), University of Kaiserslautern, Germany
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9
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Tijssen KCH, van Weerdenburg BJA, Zhang H, Janssen JWG, Feiters MC, van Bentum PJM, Kentgens APM. Monitoring Heterogeneously Catalyzed Hydrogenation Reactions at Elevated Pressures Using In-Line Flow NMR. Anal Chem 2019; 91:12636-12643. [PMID: 31508941 PMCID: PMC6796828 DOI: 10.1021/acs.analchem.9b00895] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We present a novel setup that can be used for the in-line monitoring of solid-catalyzed gas-liquid reactions. The method combines the high sensitivity and resolution of a stripline NMR detector with a microfluidic network that can withstand elevated pressures. In our setup we dissolve hydrogen gas in the solvent, then flow it with the added substrate through a catalyst cartridge, and finally flow the reaction mixture directly through the stripline NMR detector. The method is quantitative and can be used to determine the solubility of hydrogen gas in liquids; it allows in-line monitoring of hydrogenation reactions and can be used to determine the reaction kinetics of these reactions. In this work, as proof of concept we demonstrate the optimization of the Pd-catalyzed hydrogenation reactions of styrene, phenylacetylene, cyclohexene, and hex-5-en-2-one in a microfluidic context.
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Affiliation(s)
| | | | - Hainan Zhang
- Mesoscale Chemical Systems, Mesa+ Institute for Nanotechnology , University of Twente , Enschede , The Netherlands
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10
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Bornemann M, Kern S, Jurtz N, Thiede T, Kraume M, Maiwald M. Design and Validation of an Additively Manufactured Flow Cell–Static Mixer Combination for Inline NMR Spectroscopy. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.9b03746] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Martin Bornemann
- Bundesanstalt für Materialforschung und -prüfung (BAM), Richard-Willstätter-Str. 11, 12489 Berlin, Germany
- Technische Universität Berlin, Fachgebiet Verfahrenstechnik, FH 6-1, Fraunhofer Straße 33−36, 10587 Berlin, Germany
| | - Simon Kern
- Bundesanstalt für Materialforschung und -prüfung (BAM), Richard-Willstätter-Str. 11, 12489 Berlin, Germany
| | - Nico Jurtz
- Technische Universität Berlin, Fachgebiet Verfahrenstechnik, FH 6-1, Fraunhofer Straße 33−36, 10587 Berlin, Germany
| | - Tobias Thiede
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany
| | - Matthias Kraume
- Technische Universität Berlin, Fachgebiet Verfahrenstechnik, FH 6-1, Fraunhofer Straße 33−36, 10587 Berlin, Germany
| | - Michael Maiwald
- Bundesanstalt für Materialforschung und -prüfung (BAM), Richard-Willstätter-Str. 11, 12489 Berlin, Germany
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11
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Friebel A, von Harbou E, Münnemann K, Hasse H. Reaction Monitoring by Benchtop NMR Spectroscopy Using a Novel Stationary Flow Reactor Setup. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.9b03048] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Anne Friebel
- Laboratory of Engineering Thermodynamics (LTD), University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Erik von Harbou
- Laboratory of Engineering Thermodynamics (LTD), University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Kerstin Münnemann
- Laboratory of Engineering Thermodynamics (LTD), University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Hans Hasse
- Laboratory of Engineering Thermodynamics (LTD), University of Kaiserslautern, 67663 Kaiserslautern, Germany
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12
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Rudszuck T, Förster E, Nirschl H, Guthausen G. Low-field NMR for quality control on oils. Magn Reson Chem 2019; 57:777-793. [PMID: 30790362 DOI: 10.1002/mrc.4856] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 02/12/2019] [Accepted: 02/14/2019] [Indexed: 05/15/2023]
Abstract
Oil is a prominent, but multifaceted material class with a wide variety of applications. Technical oils, crude oils as well as edibles are main subclasses. In this review, the question is addressed how low-field NMR can contribute in oil characterization as an analytical tool, mainly with respect to quality control. Prerequisite in the development of a quality control application, however, is a detailed understanding of the oils and of the measurement. Low-field NMR is known as a rich methodical toolbox that was and is explored and further developed to address questions about oils, their quality, and usability as raw materials, during production and formulation as well as in use.
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Affiliation(s)
- Thomas Rudszuck
- Institute for Mechanical Engineering and Mechanics, Karlsruher Institute of Technology (KIT), Karlsruhe, Germany
| | - Eva Förster
- Institute for Mechanical Engineering and Mechanics, Karlsruher Institute of Technology (KIT), Karlsruhe, Germany
| | - Hermann Nirschl
- Institute for Mechanical Engineering and Mechanics, Karlsruher Institute of Technology (KIT), Karlsruhe, Germany
| | - Gisela Guthausen
- Institute for Mechanical Engineering and Mechanics, Karlsruher Institute of Technology (KIT), Karlsruhe, Germany
- Engler-Bunte Institute, Water Science and Technology, Karlsruher Institute of Technology (KIT), Karlsruhe, Germany
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13
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Weidener D, Singh K, Blümich B. Synthesis of α-fluoro-α,β-unsaturated esters monitored by 1D and 2D benchtop NMR spectroscopy. Magn Reson Chem 2019; 57:852-860. [PMID: 30702770 DOI: 10.1002/mrc.4843] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 01/19/2019] [Accepted: 01/21/2019] [Indexed: 06/09/2023]
Abstract
For optimization and control of pharmaceutically and industrially important reactions, chemical information is required in real time. Instrument size, handling, and operation costs are important criteria to be considered when choosing a suitable analytical method apart from sensitivity and resolution. This present study explores the use of a robust and compact nuclear magnetic resonance (NMR) spectrometer to monitor the stereo-selective formation of α-fluoro-α,β-unsaturated esters from α-fluoro-β-keto esters via deprotonation and deacylation in real time. These compounds are precursors of various pharmaceutically active substances. The real-time study revealed the deprotonation and deacylation steps of the reaction. The reaction was studied at temperatures ranging from 293 to 333 K by interleaved one-dimensional 1 H and 19 F and two-dimensional 1 H-1 H COSY experiments. The kinetic rate constants were evaluated using a pseudo first-order kinetic model. The activation energies for the deprotonation and deacylation steps were determined to 28 ± 2 and 63.5 ± 8 kJ/mol, respectively. This showed that the deprotonation step is fast compared with the deacylation step and that the deacylation step determines the rate of the overall reaction. The reaction was repeated three times at 293 K to monitor the repeatability and stability of the system. The compact NMR spectrometer provided detailed information on the mechanism and kinetics of the reaction, which is essential for optimizing the synthetic routes for stepwise syntheses of pharmaceutically active substances.
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Affiliation(s)
- Dennis Weidener
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Aachen, Germany
| | - Kawarpal Singh
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Aachen, Germany
| | - Bernhard Blümich
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Aachen, Germany
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14
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Silva PFD, Gomes BF, Lobo CMS, Queiroz Júnior LHK, Danieli E, Carmo M, Blümich B, Colnago LA. Electrochemical NMR spectroscopy: Electrode construction and magnetic sample stirring. Microchem J 2019. [DOI: 10.1016/j.microc.2019.01.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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15
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Neill JL, Yang Y, Muckle MT, Reynolds RL, Evangelisti L, Sonstrom RE, Pate BH, Gupton BF. Online Stereochemical Process Monitoring by Molecular Rotational Resonance Spectroscopy. Org Process Res Dev 2019. [DOI: 10.1021/acs.oprd.9b00089] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Justin L. Neill
- BrightSpec, Inc., 770 Harris Street Suite 104b, Charlottesville, Virginia 22903, United States
| | - Yuan Yang
- Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Matt T. Muckle
- BrightSpec, Inc., 770 Harris Street Suite 104b, Charlottesville, Virginia 22903, United States
| | - Roger L. Reynolds
- BrightSpec, Inc., 770 Harris Street Suite 104b, Charlottesville, Virginia 22903, United States
| | - Luca Evangelisti
- Dipartimento di Chimica “G. Ciamician” dell’Universita, via Selmi 2, I-40126, Bologna, Italy
| | - Reilly E. Sonstrom
- Department of Chemistry, University of Virginia, McCormick Road, Charlottesville, Virginia 22904, United States
| | - Brooks H. Pate
- Department of Chemistry, University of Virginia, McCormick Road, Charlottesville, Virginia 22904, United States
| | - B. Frank Gupton
- Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond, Virginia 23284, United States
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16
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Lobo CM, Gomes BF, Bouzouma H, Danieli E, Blümich B, Colnago LA. Improving in operando low field NMR copper electrodeposition analyses using inductively coupled coils. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2018.12.076] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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17
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Urbańczyk M, Shchukina A, Gołowicz D, Kazimierczuk K. TReNDS-Software for reaction monitoring with time-resolved non-uniform sampling. Magn Reson Chem 2019; 57:4-12. [PMID: 30255516 DOI: 10.1002/mrc.4796] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 09/10/2018] [Accepted: 09/11/2018] [Indexed: 06/08/2023]
Abstract
NMR spectroscopy, used routinely for structure elucidation, has also become a widely applied tool for process and reaction monitoring. However, the most informative of NMR methods-correlation experiments-are often useless in this kind of applications. The traditional sampling of a multidimensional FID is usually time-consuming, and thus, the reaction-monitoring toolbox was practically limited to 1D experiments (with rare exceptions, e.g., single-scan or fast-sampling experiments). Recently, the technique of time-resolved non-uniform sampling (TR-NUS) has been proposed, which allows to use standard multidimensional pulse sequences preserving the temporal resolution close to that achievable in 1D experiments. However, the method existed only as a prototype and did not allow on-the-fly processing during the reaction. In this paper, we introduce TReNDS: free, user-friendly software kit for acquisition and processing of TR-NUS data. The program works on Bruker, Agilent, and Magritek spectrometers, allowing to carry out up to four experiments with interleaved TR-NUS. The performance of the program is demonstrated on the example of enzymatic hydrolysis of sucrose.
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Affiliation(s)
- Mateusz Urbańczyk
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
- Spektrino Sp. z o.o., Warsaw, Poland
- NMR Research Unit, University of Oulu, Oulu, Finland
| | | | - Dariusz Gołowicz
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
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Jeong K, Min S, Chae H, Namgoong SK. Monitoring of hydrogenation by benchtop NMR with parahydrogen-induced polarization. Magn Reson Chem 2019; 57:44-48. [PMID: 30118555 DOI: 10.1002/mrc.4791] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 07/25/2018] [Accepted: 08/06/2018] [Indexed: 06/08/2023]
Affiliation(s)
- Keunhong Jeong
- Department of Chemistry, Korea Military Academy, Seoul, South Korea
| | - Sein Min
- Department of Chemistry, Seoul Women's University, Seoul, South Korea
| | - Heelim Chae
- Department of Chemistry, Seoul Women's University, Seoul, South Korea
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Singh K, Blümich B. Online monitoring of the kinetic isotope effect in chemical reactions with 1H and 19F low-field NMR spectroscopy. Analyst 2018; 143:4408-4421. [PMID: 30137060 DOI: 10.1039/c8an01028e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The kinetic isotope effect (KIE) describes the change in the rate of a chemical reaction by substituting one of the atoms in the reactants with one of its isotopes. Investigating the KIE and its temperature dependency in reactions renders information for reconstructing chemical processes and confirming the rate-determining step. However, conventional methods to study the KIE, e.g. by calorimetry, conductivity, titration, Raman spectroscopy etc., require calibration and sophisticated handling of the reaction calorimeter, and the data are obtained at irregular and sparse intervals. This current study employs a compact NMR system as an alternative means to determine the temperature dependency of the reaction rate and, thus, the KIE, as well as the activation energy, enthalpy, and entropy of each reaction. Here the neutral hydrolysis of acetic anhydride and ethyl trifluoroacetate was studied in H2O, D2O and H2O-D2O mixtures with 1H and 19F NMR spectroscopy. The activation energies for the hydrolysis of acetic anhydride with D2O and H2O were found to be 45 ± 2 kJ mol-1 and 40 ± 2 kJ mol-1, respectively. The activation energies of ethyl trifluoroacetate hydrolysis via19F NMR spectroscopy were determined to 46.7 ± 1 kJ mol-1 and 54.9 ± 1 kJ mol-1 for the reaction with H2O and D2O, respectively, and via1H NMR spectroscopy to 48 ± 3 kJ mol-1 and 55.8 ± 1 kJ mol-1. The differences in rate constants and activation energies for both reactions in H2O and D2O are due to the kinetic isotope effect, involving the breakage and formation of O-H and O-D bonds during the rate-determining step. The proton inventory studies were performed for both the reactions for determining the isotopic fractionation factors for the given transition states of the reactions which help to predict the reaction mechanisms of other similar reactions. The compact NMR system is a relevant and practical tool to unmask precise reaction pathways, by tracing the KIE in real time with densely sampled data, which are essential for obtaining accurate rate constants.
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Affiliation(s)
- Kawarpal Singh
- Institute für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, D-52074, Aachen, Germany.
| | - Bernhard Blümich
- Institute für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, D-52074, Aachen, Germany.
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Kern S, Meyer K, Guhl S, Gräßer P, Paul A, King R, Maiwald M. Online low-field NMR spectroscopy for process control of an industrial lithiation reaction—automated data analysis. Anal Bioanal Chem 2018; 410:3349-60. [DOI: 10.1007/s00216-018-1020-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 02/22/2018] [Accepted: 03/12/2018] [Indexed: 01/13/2023]
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Rodrigues EJDR, Neto RPC, Sebastião PJO, Tavares MIB. Real-time monitoring by proton relaxometry of radical polymerization reactions of acrylamide in aqueous solution. POLYM INT 2018. [DOI: 10.1002/pi.5546] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Elton Jorge da Rocha Rodrigues
- Instituto de Macromoléculas Professora Eloisa Mano da Unidade Federal do Rio de Janeiro; Centro de Tecnologia, Ilha do Fundão; Rio de Janeiro Brazil
| | - Roberto Pinto Cucinelli Neto
- Instituto de Macromoléculas Professora Eloisa Mano da Unidade Federal do Rio de Janeiro; Centro de Tecnologia, Ilha do Fundão; Rio de Janeiro Brazil
| | - Pedro José Oliveira Sebastião
- Center of Physics and Engineering of Advanced Materials, Instituto Superior Técnico; Universidade de Lisboa; Portugal
| | - Maria Inês Bruno Tavares
- Instituto de Macromoléculas Professora Eloisa Mano da Unidade Federal do Rio de Janeiro; Centro de Tecnologia, Ilha do Fundão; Rio de Janeiro Brazil
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Abstract
NMR spectroscopy is an indispensable method of analysis in chemistry, which until recently suffered from high demands for space, high costs for acquisition and maintenance, and operational complexity. This has changed with the introduction of compact NMR spectrometers suitable for small-molecule analysis on the chemical workbench. These spectrometers contain permanent magnets giving rise to proton NMR frequencies between 40 and 80 MHz. The enabling technology is to make small permanent magnets with homogeneous fields. Tabletop instruments with inhomogeneous fields have been in use for over 40 years for characterizing food and hydrogen-containing materials by relaxation and diffusion measurements. Related NMR instruments measure these parameters in the stray field outside the magnet. They are used to inspect the borehole walls of oil wells and to test objects nondestructively. The state-of-the-art of NMR spectroscopy, imaging and relaxometry with compact instruments is reviewed.
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Affiliation(s)
- Bernhard Blümich
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Aachen, Germany
| | - Kawarpal Singh
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Aachen, Germany
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23
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Affiliation(s)
- Bernhard Blümich
- Institut für Technische und Makromolekulare Chemie; RWTH Aachen University; Aachen Deutschland
| | - Kawarpal Singh
- Institut für Technische und Makromolekulare Chemie; RWTH Aachen University; Aachen Deutschland
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Singh K, Danieli E, Blümich B. Desktop NMR spectroscopy for real-time monitoring of an acetalization reaction in comparison with gas chromatography and NMR at 9.4 T. Anal Bioanal Chem 2017; 409:7223-7234. [PMID: 29030668 DOI: 10.1007/s00216-017-0686-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 09/18/2017] [Accepted: 09/29/2017] [Indexed: 10/18/2022]
Abstract
Monitoring of chemical reactions in real-time is in demand for process control. Different methods such as gas chromatography (GC), mass spectroscopy, infrared spectroscopy, and nuclear magnetic resonance (NMR) are used for that purpose. The current state-of-the-art compact NMR systems provide a useful method to employ with various reaction conditions for studying chemical reactions inside the fume hood at the chemical workplace. In the present study, an acetalization reaction was investigated with compact NMR spectroscopy in real-time. Acetalization is used for multistep synthesis of the variety of organic compounds to protect particular chemical groups. A compact 1 T NMR spectrometer with a permanent magnet was employed to monitor the acid catalyzed acetalization of the p-nitrobenzaldehyde with ethylene glycol. The concentrations of both reactant and product were followed by peak integrals in single-scan 1H NMR spectra as a function of time. The reaction conditions were varied in terms of temperature, agitation speed, catalyst loading, and feed concentrations in order to determine the activation energy with the help of a pseudo-homogeneous kinetic model. For low molar ratios of aldehyde and glycol, the equilibrium conversions were lower than for the stoichiometric ratio. Increasing catalyst concentration leads to faster conversion. The data obtained with low-field NMR spectroscopy were compared with data from GC and NMR spectroscopy at 9.4 T acquired in batch mode by extracting samples at regular time intervals. The reaction kinetics followed by either method agreed well. The activation energies for forward and backward reactions were determined by real-time monitoring with compact NMR at 1 T were 48 ± 5 and 60 ± 4 kJ/mol, respectively. The activation energies obtained with gas chromatography for forward and backward reactions were 48 ± 4 and 51 ± 4 kJ/mol. The equilibrium constant decreases with increasing temperature as expected for an exothermic reaction. The impact of dense sampling with online NMR and sparse sampling with GC was observed on the kinetic outcome using the same kinetic model. Graphical abstract Acetalization reaction kinetics were monitored with real-time desktop NMR spectroscopy at 1 T. Each data point was obtained at regular intervals with a single shot in 15 s. The kinetics was compared with sparsely sampled data obtained with GC and NMR at 9.4 T.
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Affiliation(s)
- Kawarpal Singh
- Institut für Technische Chemie und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany.
| | - Ernesto Danieli
- Institut für Technische Chemie und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Bernhard Blümich
- Institut für Technische Chemie und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
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Affiliation(s)
- Joris J. Haven
- Polymer Reaction Design Group; Institute for Materials Research (imo-imomec); Hasselt University; Campus Diepenbeek Building D 3590 Diepenbeek Belgium
| | - Tanja Junkers
- Polymer Reaction Design Group; Institute for Materials Research (imo-imomec); Hasselt University; Campus Diepenbeek Building D 3590 Diepenbeek Belgium
- IMEC division IMOMEC; Wetenschapspark 1 3590 Diepenbeek Belgium
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Michalik-Onichimowska A, Kern S, Riedel J, Panne U, King R, Maiwald M. "Click" analytics for "click" chemistry - A simple method for calibration-free evaluation of online NMR spectra. J Magn Reson 2017; 277:154-161. [PMID: 28288418 DOI: 10.1016/j.jmr.2017.02.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/23/2017] [Accepted: 02/25/2017] [Indexed: 06/06/2023]
Abstract
Driven mostly by the search for chemical syntheses under biocompatible conditions, so called "click" chemistry rapidly became a growing field of research. The resulting simple one-pot reactions are so far only scarcely accompanied by an adequate optimization via comparably straightforward and robust analysis techniques possessing short set-up times. Here, we report on a fast and reliable calibration-free online NMR monitoring approach for technical mixtures. It combines a versatile fluidic system, continuous-flow measurement of 1H spectra with a time interval of 20s per spectrum, and a robust, fully automated algorithm to interpret the obtained data. As a proof-of-concept, the thiol-ene coupling between N-boc cysteine methyl ester and allyl alcohol was conducted in a variety of non-deuterated solvents while its time-resolved behaviour was characterized with step tracer experiments. Overlapping signals in online spectra during thiol-ene coupling could be deconvoluted with a spectral model using indirect hard modeling and were subsequently converted to either molar ratios (using a calibration-free approach) or absolute concentrations (using 1-point calibration). For various solvents the kinetic constant k for pseudo-first order reaction was estimated to be 3.9h-1 at 25°C. The obtained results were compared with direct integration of non-overlapping signals and showed good agreement with the implemented mass balance.
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Affiliation(s)
- Aleksandra Michalik-Onichimowska
- Bundesanstalt für Materialforschung und -prüfung (BAM), Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany; Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany; School of Analytical Sciences Adlershof, Humboldt-Universität zu Berlin, Zum Groβen Windkanal 6, 12489 Berlin, Germany
| | - Simon Kern
- Bundesanstalt für Materialforschung und -prüfung (BAM), Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany
| | - Jens Riedel
- Bundesanstalt für Materialforschung und -prüfung (BAM), Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany
| | - Ulrich Panne
- Bundesanstalt für Materialforschung und -prüfung (BAM), Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany; Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany; School of Analytical Sciences Adlershof, Humboldt-Universität zu Berlin, Zum Groβen Windkanal 6, 12489 Berlin, Germany
| | - Rudibert King
- Department Measurement and Control, Institute of Process Engineering, Berlin University of Technology, Hardenbergstr. 36a, 10623 Berlin, Germany
| | - Michael Maiwald
- Bundesanstalt für Materialforschung und -prüfung (BAM), Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany.
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Rehm TH, Hofmann C, Reinhard D, Kost HJ, Löb P, Besold M, Welzel K, Barten J, Didenko A, Sevenard DV, Lix B, Hillson AR, Riegel SD. Continuous-flow synthesis of fluorine-containing fine chemicals with integrated benchtop NMR analysis. REACT CHEM ENG 2017. [DOI: 10.1039/c7re00023e] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fluorine fine chemical synthesis takes a step ahead using integrated NMR online-analysis with a benchtop NMR spectrometer.
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Affiliation(s)
| | | | | | | | | | | | | | - Jan Barten
- Hansa Fine Chemicals GmbH, BITZ
- 28359 Bremen
- Germany
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29
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Abstract
An approach for resolution enhancement is proposed, for data acquired on low field tabletop NMR spectrometers by employing processing-based (generalized indirect covariance) advancements in pure shift NMR.
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Affiliation(s)
- Kavitha Rachineni
- UM-DAE Centre for Excellence in Basic Sciences
- University of Mumbai
- Mumbai 400 098
- India
| | | | - Ramakrishna V. Hosur
- UM-DAE Centre for Excellence in Basic Sciences
- University of Mumbai
- Mumbai 400 098
- India
- Department of Chemical Sciences
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31
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32
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34
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Kern S, Meyer K, Paul A, Maiwald M. Ugly Spectra and Lousy interfaces - Challenges for Compact NMR Spectroscopy in Process Control. CHEM-ING-TECH 2016. [DOI: 10.1002/cite.201650243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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35
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Zientek N, Laurain C, Meyer K, Paul A, Engel D, Guthausen G, Kraume M, Maiwald M. Automated data evaluation and modelling of simultaneous (19) F-(1) H medium-resolution NMR spectra for online reaction monitoring. Magn Reson Chem 2016; 54:513-520. [PMID: 25854892 DOI: 10.1002/mrc.4216] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 10/31/2014] [Accepted: 01/19/2015] [Indexed: 06/04/2023]
Abstract
Medium-resolution nuclear magnetic resonance spectroscopy (MR-NMR) currently develops to an important analytical tool for both quality control and process monitoring. In contrast to high-resolution online NMR (HR-NMR), MR-NMR can be operated under rough environmental conditions. A continuous re-circulating stream of reaction mixture from the reaction vessel to the NMR spectrometer enables a non-invasive, volume integrating online analysis of reactants and products. Here, we investigate the esterification of 2,2,2-trifluoroethanol with acetic acid to 2,2,2-trifluoroethyl acetate both by (1) H HR-NMR (500 MHz) and (1) H and (19) F MR-NMR (43 MHz) as a model system. The parallel online measurement is realised by splitting the flow, which allows the adjustment of quantitative and independent flow rates, both in the HR-NMR probe as well as in the MR-NMR probe, in addition to a fast bypass line back to the reactor. One of the fundamental acceptance criteria for online MR-MNR spectroscopy is a robust data treatment and evaluation strategy with the potential for automation. The MR-NMR spectra are treated by an automated baseline and phase correction using the minimum entropy method. The evaluation strategies comprise (i) direct integration, (ii) automated line fitting, (iii) indirect hard modelling (IHM) and (iv) partial least squares regression (PLS-R). To assess the potential of these evaluation strategies for MR-NMR, prediction results are compared with the line fitting data derived from the quantitative HR-NMR spectroscopy. Although, superior results are obtained from both IHM and PLS-R for (1) H MR-NMR, especially the latter demands for elaborate data pretreatment, whereas IHM models needed no previous alignment. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Nicolai Zientek
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489, Berlin, Germany
| | - Clément Laurain
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489, Berlin, Germany
- École Nationale Supérieure de Chimie de Lille, Avenue Mendeleiev CS 90108, 59652, Villeneuve D'ascq Cedex, France
| | - Klas Meyer
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489, Berlin, Germany
| | - Andrea Paul
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489, Berlin, Germany
| | - Dirk Engel
- Pro2NMR, Institute of Mechanical Process Engineering and Mechanics and Institute of Biological Interfaces, KIT, Adenauerring 20b, 76131, Karlsruhe, Germany
| | | | - Matthias Kraume
- Department of Chemical Engineering, Technische Universität Berlin, Straße des 17. Juni 136, MA 5-7, 10623, Berlin, Germany
| | - Michael Maiwald
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489, Berlin, Germany
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Steinhof O, Scherr G, Hasse H. Investigation of the reaction of 1,3-dimethylurea with formaldehyde by quantitative on-line NMR spectroscopy: a model for the urea-formaldehyde system. Magn Reson Chem 2016; 54:457-476. [PMID: 26095823 DOI: 10.1002/mrc.4274] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 04/20/2015] [Accepted: 05/08/2015] [Indexed: 06/04/2023]
Abstract
Quantitative on-line NMR spectroscopy is applied to study equilibria and reaction kinetics of the reaction of formaldehyde with 1,3-dimethylurea. This reaction system serves as a model system for the much more complex but industrially relevant urea-formaldehyde system. The aim is to study individual reactions and intermediates. The 1,3-dimethylurea-formaldehyde system undergoes only four reactions and, unlike urea-formaldehyde, does not form polymers. The following reactions are studied in detail: (1) the hydroxymethylation, (2) the formation of hemiformals of the hydroxymethylated intermediate, and (3) two condensation reactions of which the first leads to methylene bridges, the other to ether bridges. NMR spectroscopic chemical shift data of the reacting species are provided for the (1) H, (13) C, and (15) N domains. Equilibrium data of reactions (1), (2), and (3) are determined by quantitative (1) H and (13) C NMR spectroscopy at molar ratios of formaldehyde to 1,3-dimethylurea between 1:2 and 16:1 at a pH value of 8.5. Reaction kinetic experiments using an NMR spectrometer coupled to a batch reactor led to a reaction kinetic model parametrized with true species concentrations. The model takes into account reactions (1), (2), and (3). It describes the reaction system well for molar ratios of 1:1, 2:1, and 4:1, temperatures of 303 to 333K, and pH values from 5.0 to 9.5. Dilution experiments with a micro mixer coupled to the NMR spectrometer are conducted to estimate the time to equilibrium of reaction (2) of which the time constant is significantly lower than those of reactions (1) and (3). Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Oliver Steinhof
- Institute of Thermodynamics and Thermal Process Engineering, Universität Stuttgart, Stuttgart, 70569, Germany
| | | | - Hans Hasse
- Laboratory of Engineering Thermodynamics, University of Kaiserslautern, Kaiserslautern, 67663, Germany
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Dunn AL, Codina A, Foley DA, Marquez BL, Zell MT. A detailed mechanistic investigation into the reaction of 3-methylpentanoic acid with Meldrum's acid utilizing online NMR spectroscopy. Magn Reson Chem 2016; 54:477-484. [PMID: 26332370 DOI: 10.1002/mrc.4317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 07/14/2015] [Accepted: 07/21/2015] [Indexed: 06/05/2023]
Abstract
A thorough investigation into the mechanism of the reaction of 3-methylpentanoic acid and Meldrum's acid using online NMR spectroscopy is reported. This study is an expansion of a previous analysis of this chemical transformation in the synthesis of an active pharmaceutical ingredient imagabalin. The 3-methylpentanoic acid analogue reveals similar behavior under the reaction conditions. Online NMR spectroscopy and offline characterization experiments reveal new information about the mechanism, providing conclusive spectroscopic evidence for the previously hypothesized dimer anhydride intermediate species 3-methylpentanoic anhydride as a productive intermediate. The presence of an acyl chloride intermediate species, 3-methylpentanoyl chloride, is also revealed for the first time in this synthesis. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Anna L Dunn
- Analytical Research and Development, Pfizer Worldwide Research and Development, 445 Eastern Point Road, Groton, CT, 06340, USA
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, WI, 53706, USA
| | - Anna Codina
- Bruker UK Limited, Banner Lane, Coventry, CV4 9GH, UK
| | - David A Foley
- Analytical Research and Development, Pfizer Worldwide Research and Development, 445 Eastern Point Road, Groton, CT, 06340, USA
| | | | - Mark T Zell
- Analytical Research and Development, Pfizer Worldwide Research and Development, 445 Eastern Point Road, Groton, CT, 06340, USA
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Tijssen KCH, Bart J, Tiggelaar RM, Janssen JWGH, Kentgens APM, van Bentum PJM. Spatially resolved spectroscopy using tapered stripline NMR. J Magn Reson 2016; 263:136-146. [PMID: 26796112 DOI: 10.1016/j.jmr.2015.12.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 12/15/2015] [Accepted: 12/16/2015] [Indexed: 06/05/2023]
Abstract
Magnetic field B0 gradients are essential in modern Nuclear Magnetic Resonance spectroscopy and imaging. Although RF/B1 gradients can be used to fulfill a similar role, this is not used in common practice because of practical limitations in the design of B1 gradient coils. Here we present a new method to create B1 gradients using stripline RF coils. The conductor-width of a stripline NMR chip and the strength of its radiofrequency field are correlated, so a stripline chip can be tapered to produce any arbitrary shaped B1 field gradient. Here we show the characterization of this tapered stripline configuration and demonstrate three applications: magnetic resonance imaging on samples with nL-μL volumes, reaction monitoring of fast chemical reactions (10(-2)-10(1)s) and the compensation of B0 field gradients to obtain high-resolution spectra in inhomogeneous magnetic fields.
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Affiliation(s)
- Koen C H Tijssen
- Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - Jacob Bart
- Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - Roald M Tiggelaar
- Mesa+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands
| | - J W G Hans Janssen
- Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - Arno P M Kentgens
- Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - P Jan M van Bentum
- Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands.
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Goldbach M, Danieli E, Perlo J, Kaptein B, Litvinov VM, Blümich B, Casanova F, Duchateau AL. Preparation of Grignard reagents from magnesium metal under continuous flow conditions and on-line monitoring by NMR spectroscopy. Tetrahedron Lett 2016. [DOI: 10.1016/j.tetlet.2015.11.077] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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41
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Kind J, Thiele CM. Still shimming or already measuring?--Quantitative reaction monitoring for small molecules on the sub minute timescale by NMR. J Magn Reson 2015; 260:109-115. [PMID: 26433632 DOI: 10.1016/j.jmr.2015.09.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 09/11/2015] [Accepted: 09/13/2015] [Indexed: 06/05/2023]
Abstract
In order to enable monitoring of rapidly occurring reactions Wagner et al. recently presented a simple scheme for 1D NMR experiments with continuous data acquisition, without inter-scan delays, using a spatially-selective and frequency-shifted excitation approach (Wagner et al., 2013). This scheme allows acquisition of proton spectra with temporal resolutions on the millisecond timescale. Such high temporal resolutions are desired in the case of reaction monitoring using stopped flow setups. In regular (1)H NMR-spectra without spatial selection the line width increases for a given shim setting with changes in sample volume, susceptibility, convection and temperature or concentration gradients due to the disturbance of magnetic field homogeneity. Concerning reaction monitoring this is unfortunate as shimming prior to acquisition becomes necessary to obtain narrow signals after injection of a reactant into an NMR sample. Even automatic shim routines may last up to minutes. Thus fast reactions can hardly be monitored online without large hardware dead times in a single stopped flow experiment. This problem is reduced in the spatially-selective and frequency-shifted continuous NMR experiment as magnetic field inhomogeneties are less pronounced and negative effects on the obtained line shapes are reduced as pointed out by Bax and Freeman (1980) [2] and demonstrated by Wagner et al. (2013). Here we present the utilization of this technique for observation of reactions in small molecule systems in which chemical conversion and longitudinal relaxation occur on the same timescale. By means of the alkaline ethyl acetate hydrolysis, a stoichiometric reaction, we show advantages of spatially-selective excitation on both temporal resolution and line shapes in stopped flow experiments. Results are compared to data obtained by non-selective small angle excitation experiments.
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Affiliation(s)
- J Kind
- Clemens-Schöpf-Institute for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, D-64287 Darmstadt, Germany
| | - C M Thiele
- Clemens-Schöpf-Institute for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, D-64287 Darmstadt, Germany.
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Kock FVC, Colnago LA. Rapid and simultaneous relaxometric methods to study paramagnetic ion complexes in solution: An alternative to spectrophotometry. Microchem J 2015. [DOI: 10.1016/j.microc.2015.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Mitchell J, Howe AM, Clarke A. Real-time oil-saturation monitoring in rock cores with low-field NMR. J Magn Reson 2015; 256:34-42. [PMID: 25996514 DOI: 10.1016/j.jmr.2015.04.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 04/21/2015] [Accepted: 04/22/2015] [Indexed: 06/04/2023]
Abstract
Nuclear magnetic resonance (NMR) provides a powerful suite of tools for studying oil in reservoir core plugs at the laboratory scale. Low-field magnets are preferred for well-log calibration and to minimize magnetic-susceptibility-induced internal gradients in the porous medium. We demonstrate that careful data processing, combined with prior knowledge of the sample properties, enables real-time acquisition and interpretation of saturation state (relative amount of oil and water in the pores of a rock). Robust discrimination of oil and brine is achieved with diffusion weighting. We use this real-time analysis to monitor the forced displacement of oil from porous materials (sintered glass beads and sandstones) and to generate capillary desaturation curves. The real-time output enables in situ modification of the flood protocol and accurate control of the saturation state prior to the acquisition of standard NMR core analysis data, such as diffusion-relaxation correlations. Although applications to oil recovery and core analysis are demonstrated, the implementation highlights the general practicality of low-field NMR as an inline sensor for real-time industrial process control.
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Affiliation(s)
- J Mitchell
- Schlumberger Gould Research, High Cross, Madingley Road, Cambridge CB3 0EL, UK.
| | - A M Howe
- Schlumberger Gould Research, High Cross, Madingley Road, Cambridge CB3 0EL, UK
| | - A Clarke
- Schlumberger Gould Research, High Cross, Madingley Road, Cambridge CB3 0EL, UK
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