A Safe and Efficient Synthetic Route to a 2,5-Dimethyl-1-aryl-1<i>H</i>-imidazole Intermediate

Sosa, Ana Carolina Barrios; Williamson, R. Thomas; Conway, Ryan; Shankar, Ashish; Sumpter, Rosline; Cleary, Thomas P.

doi:10.1021/op100335q

Cited by 22 publications

(21 citation statements)

References 7 publications

(6 reference statements)

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“…As with highfield instruments, some benchtop NMR spectrometers can be equipped with static NMR tubes or flow cells, and some are able to acquire data in protio solvent systems (in addition to traditional deuterated solvent systems). The ability to analyze samples in protio solvents [20] both reduces the cost of analysis and enables reaction monitoring under more realistic reaction conditions [15,19,21,22].…”

Section: Introductionmentioning

confidence: 99%

Exploration of continuous‐flow benchtop NMR acquisition parameters and considerations for reaction monitoring

Maschmeyer

Prieto

Grunert

et al. 2020

Magnetic Reson in Chemistry

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This study focused on fundamental data acquisition parameter selection for a benchtop nuclear magnetic resonance (NMR) system with continuous flow, applicable for reaction monitoring. The effect of flow rate on the mixing behaviors within a flow cell was observed, along with an exponential decay relationship between flow rate and the apparent spin-lattice relaxation time (T1*) of benzaldehyde. We also monitored sensitivity (as determined by signal-to-noise ratios; SNRs) under various flow rates, analyte concentrations, and temperatures of the analyte flask. Results suggest that a maximum SNR can be achieved with low to medium flow rates and higher analyte concentrations. This was consistent with data collected with parameters that promote either slow or fast data acquisition. We further consider the effect of these conditions on the analyte's residence time, T1*, and magnetic field inhomogeneity that is a product of continuous flow. Altogether, our results demonstrate how fundamental acquisition parameters can be manipulated to achieve optimal data acquisition in continuous-flow NMR systems.

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Section: Introductionmentioning

confidence: 99%

Exploration of continuous‐flow benchtop NMR acquisition parameters and considerations for reaction monitoring

Maschmeyer

Prieto

Grunert

et al. 2020

Magnetic Reson in Chemistry

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“…Online coupling of NMR spectrometers was first developed with HPLC 3 – 8 and SFC 9, using NMR as an analytical detector with high spectral dispersion. Flow NMR probes were developed 10 to hyphenate different reactor systems and enable online monitoring of processes in the time range of several hours down to a few minutes 11 – 13.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Online NMR Spectroscopy in a Nutshell

Zientek

Meyer

Kern

et al. 2016

Chemie Ingenieur Technik

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Online NMR spectroscopy is an excellent tool to study complex reacting multicomponent mixtures and gain process insight and understanding. For online studies under process conditions, flow NMR probes can be used in a wide range of temperature and pressure. This paper compiles the most important aspects towards quantitative process NMR spectroscopy in complex multicomponent mixtures and provides examples. After NMR spectroscopy is introduced as an online method and for technical samples without sample preparation in deuterated solvents, influences of the residence time distribution, pre-magnetization, and cell design are discussed. NMR acquisition and processing parameters as well as data preparation methods are presented and the most practical data analysis strategies are introduced.

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“…However, the NMR tube is a poor model for a practical reactor and neglects many parameters such as stir rate and mixing. In this case, the best option is to interrogate the reaction in the reactor via tubeless NMR, in which the reactor is directly connected to the NMR flow cell . This approach is an emerging field for in situ reaction monitoring.…”

Section: Introductionmentioning

confidence: 99%

“…In this case, the best option is to interrogate the reaction in the reactor via tubeless NMR, in which the reactor is directly connected to the NMR flow cell. [5][6][7][8][9][10][11][12][13] This approach is an emerging field for in situ reaction monitoring. High-field NMR instruments have been applied often as they have the required sensitivity to observe reactions in the concentrations typically employed.…”

Section: Introductionmentioning

confidence: 99%

Monitoring chemical reactions by low‐field benchtop NMR at 45 MHz: pros and cons

Elipe

Milburn

2015

Magnetic Reson in Chemistry

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Monitoring chemical reactions is the key to controlling chemical processes where NMR can provide support. High-field NMR gives detailed structural information on chemical compounds and reactions; however, it is expensive and complex to operate. Conversely, low-field NMR instruments are simple and relatively inexpensive alternatives. While low-field NMR does not provide the detailed information as the high-field instruments as a result of their smaller chemical shift dispersion and the complex secondary coupling, it remains of practical value as a process analytical technology (PAT) tool and is complimentary to other established methods, such as ReactIR and Raman spectroscopy. We have tested a picoSpin-45 (currently under ThermoFisher Scientific) benchtop NMR instrument to monitor three types of reactions by 1D (1) H NMR: a Fischer esterification, a Suzuki cross-coupling, and the formation of an oxime. The Fischer esterification is a relatively simple reaction run at high concentration and served as proof of concept. The Suzuki coupling is an example of a more complex, commonly used reaction involving overlapping signals. Finally, the oxime formation involved a reaction in two phases that cannot be monitored by other PAT tools. Here, we discuss the pros and cons of monitoring these reactions at a low-field of 45 MHz by 1D (1) H NMR. Copyright © 2015 John Wiley & Sons, Ltd.

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A Safe and Efficient Synthetic Route to a 2,5-Dimethyl-1-aryl-1H-imidazole Intermediate

Cited by 22 publications

References 7 publications

Exploration of continuous‐flow benchtop NMR acquisition parameters and considerations for reaction monitoring

Exploration of continuous‐flow benchtop NMR acquisition parameters and considerations for reaction monitoring

Quantitative Online NMR Spectroscopy in a Nutshell

Monitoring chemical reactions by low‐field benchtop NMR at 45 MHz: pros and cons

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