Reaction Monitoring

A new, innovative and powerful analytical system for the lab bench
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On-line NMR reaction monitoring

NMR reaction monitoring is an excellent technique for determining reaction kinetics as well as reaction end points.  The measurements are quantitative with only minimal calibration.  The signal has a linear response to concentration and it is generally not sensitive to the matrix.  The measurement is of the complete sample and is non-destructive.

The Spinsolve high-resolution benchtop NMR spectrometer can be installed directly in the fume hood of a chemistry lab to monitor the progress of chemical reactions on-line. Reactants can be pumped in continuous mode from the reactor to the magnet and back using just standard PTFE tubing or using PTFE tubing plus a glass flow cell.

RM Brochure Page 1 Main Image sm

Magritek has created two solution kits for reaction monitoring: one using a glass flow tube with an expanded 4mm ID section in the measurement zone and minimal ID outside of that; the other a very cost effective solution using just PTFE tubing and a glass guide tube, as well as the pump.

RM Brochure Page 4 System Sketches

The pump can be set to operate in continuous or stop-flow mode to acquire points with a time resolution of about 15 seconds, is placed in the flow-loop after the magnet in order to minimise the tubing length that goes from the reactor to the sensitive volume of the Spinsolve.

The reaction itself can be carried out at temperatures of up to about 80 °C. When the reaction mixture is pumped through the bore of the magnet using 2 mm o. d. PTFE tubing, it naturally cools down to room temperature as it flows along the length of the tubing at room temperature.

The Spinsolve software enables users to easily set up either continuous flow or stop flow measurements.  See the brochure for more detail.

The Magritek Spinsolve Advantage

  • No deuterated solvents needed
  • Large sample volume for high sensitivity
  • High spectral resolution
  • Excellent time resolution
  • High stability with external lock
  • Very easy to use

You can download a PDF file of the Magritek Reaction Monitoring Brochure here.

For further information, please contact:

Online monitoring of the formation of a diimine

Imines, also named Schiff’s bases, are easy to synthesize and allow the use of a large variety of starting materials (i.e. amine and aldehyde) for the condensation reaction. Therefore, these compounds are very popular in different areas. In coordination chemistry, Schiff’s bases are used as ligands to obtain metal complexes, like the Salen ligand or the ligand of the Jacobsen´s catalyst [1]. In the dyes and pigmentsarea [2], metal complex dyes of nickel with Schiff’s bases are used [3]. On the other hand, porphyrinSchiff’s base ligand compounds have photoluminescence and/or electrochemical activity. [4] In pharmacy, numerous Schiff’s bases are potential bioactive cores, that can have useful biological activities. [5] In biochemistry, Schiff’s bases are commonly used as enzymatic intermediates. Therefore, online monitoring of this reaction is important to understand the mechanism and the formation of intermediates. In this note, the application of benchtop NMR to study this kind of reaction is demonstrated taking as an example the reaction between phenylenediame and isobutyraldehyde in acetonitrile to form the diimine product
(see Fig. 1). The results reported in this note are in good agreement with data collected on a 400 MHz spectrometer previously reported in reference [6].

Online Monitoring of the N-acetylation Reaction of L-Phenylalanine Online

Online monitoring of chemical reactions is a fast-growing field finding applications in R&D labs, pilot plants,and large chemical production plants where fully automated analyzers provide feedback to control thereactor. Today, mostly optical techniques like near-infrared and Raman spectroscopy are applied onlinedue to their simple implementation using immersion probes directly mounted within reaction vesselsor pipes. However, these methods require complex data analysis based on multivariate techniques like partial least squares regression (PLS-R), and demanding calibrations valid for all states during the reaction. NMR spectroscopy has the advantage of being an absolute method. The direct proportionality of the NMR signal amplitude to the concentration of the molecules in the sample allows for an absolute quantification without the need for calibration and is independent of the composition of the sample or the solvent used in the preparation. With the availability of the Spinsolve compact benchtop NMR systems, the NMR spectrometer can be brought directly next to the reaction setup in the lab or even in plant.
Permanent magnet systems do not need cryogens or special maintenance and only minimal training is required for personnel to perform the measurements due to the ease of use.
In this application note we show the performance of a Spinsolve 60 MHz ULTRA to monitor the
N-Acetylation of L-Phenylalanine with acetic anhydride (Fig. 1). L-Phenylalanine is an essential aminoacid used in a variety of industrial processes, e.g. as reactant in the synthesis of the ACE-inhibitor Alacepril, as well as in the production of the well-known, non-saccharide sweetener, Aspartam. In many chemical processes involving amino acids the reactive centers must be protected to ensure the required regioselectivity of the reaction. In this example the acetylation of the amine works as a protection group to move the reactive center towards the acid functionality of the L Phenylalanine. Besides monitoring the progress of the reaction, the NMR spectra also provide information about the addition of reactants step and the consequent hydrolysis of the reactant acetic anhydride.

On-line Reaction Monitoring of Alcoholic Fermentation

NMR spectroscopy is an excellent technique for monitoring organic reactions due to its high degree of functional group specificity. This allows one to integrate over one or more sections of the spectrum to track the increase or decrease of the species of interest.
The Spinsolve high-resolution benchtop NMR spectrometer now makes such reaction monitoring extremely easy to set up and run for many reaction processes. It can be installed directly in a fume hood of a chemistry lab to monitor the progress of chemical reactions on-line. Reactants can be pumped in continuous mode from the reactor to the magnet and back using standard PTFE tubing.
Fermentation is a naturally occurring chemical processes – and indeed one of the most popular around the world!
In this application note we show how easy it is to monitor a simple fermentation process, and to easily get chemical conversion rates and to see where the optimal end point has occurred.