Reaction Monitoring

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.

Reaction Monitoring

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.

NMR reaction monitoring is an excellent technique for determining reaction kinetics as well as reaction end points. NMR measurements are quantitative and NMR signals change in a linear way as concentrations vary. The NMR technique is not sensitive to the matrix of the sample. NMR measurements are non-destructive and the complete sample material being inside the NMR coil is analyzed. 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  a glass flow cell. 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. The other one, is a very cost effective solution using just PTFE tubing and a glass guide tube, as well as the pump.

The pump can be set to operate in continuous or stop-flow mode to acquire points with a time resolution of about 15 seconds. It 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 100 °C. When the reaction mixture is pumped through the bore of the magnet using PTFE tubing, it naturally cools down to room temperature as it flows along the length of the tubing at.The Spinsolve software enables users to easily set up either continuous flow or stop flow measurements.  

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

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

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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. In the dyes and pigments area, metal complex dyes of nickel with Schiff’s bases are used. On the other hand, porphyrin Schiff’s base ligand compounds have photoluminescence and/or electrochemical activity. In pharmacy, numerous Schiff’s bases are potential bioactive cores, that can have useful biological activities. 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. Read more …

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 the reactor. 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. Read more …

 

Fluorine containing scaffolds and building blocks play a remarkable role within drug discovery in medicinal chemistry for the synthesis of Active Pharmaceutical Ingredients (API). The fluorine atom holds some key advantages in terms of pharmacokinetic and physicochemical properties. Some of the major advantages are the improved metabolic stability and the enhanced membrane permeation that allow for a significantly higher bioavailability of fluorine-containing drugs. Read more…                                                                                                                                               On-line reaction monitoring by NMR has proven to be a valuable tool in process control, as it allows for a deep insight into mechanisms and kinetics of chemical reactions at laboratory, as well as pilot-scale. In previous Application Notes, we have demonstrated the benefits of using the Spinsolve™ Reaction Monitoring Kit to follow the progress of different reactions by 1H-NMR spectroscopy. In this application note, we show how the course of an SNAr reaction can be monitored on-line by acquiring both 1H- and 19F-NMR spectra sequentially in a continuous mode. For these particular experiments we employed our Spinsolve™ 60 MHz HF ULTRA system, but all Spinsolve™ models come with capabilities to acquire 1Hand 19F-NMR spectra without retuning or recalibration. Read more …