The measurements of NMR spectra are sensitive to the reaction kinetics and molecular structure owing to the chemical specificity. The measurements recorded are quantitative and require minimal calibration. The signal responds linearly with the concentration and is matrix insensitive. The measurements are non-destructive and made for the whole sample.
Spinsolve® Benchtop NMR Spectrometer
The Spinsolve® Benchtop NMR Spectrometer (Figure 1) has high sensitivity and large sample volume, enabling rapid measurements with high signal-to-noise ratios.
Figure 1. Reaction monitoring with the Spinsolve® Benchtop NMR Spectrometer and the glass flow cell.
The following are the other advantages of the Spinsolve® Benchtop NMR Spectrometer:
- Provides better stability for prolonged measurements devoid of user intervention
- High spectral resolution with narrow base width for precise component integrals
- The operation is user-friendly and does not require a skilled or dedicated technician
The experiment for monitoring the reaction can be easily set up using the Spinsolve® software scripting (Figure 2). The example illustrates the monitoring of the oxidation process of triphenylphosphine to triphenylphosphine sulfide with a signal generated from the nucleus of phosphorous. The span of the experiment is about 2h with the recording of a spectrum done every 20min. Mnova is used to plot the results.
Figure 2. The script can also include processing instructions for Mnova to generate the component qualities over time.
Two hardware kit options have been offered by Magritek to monitor reactions (Figure 3). Complete control over the operation of the pump enabling continuous flow or stop flow operations has been provided by the Spinsolve® software.
PTFE Tubing (Kit RM1)
A single PTFE tubing piece having a glass tube guide within the spectrometer bore to center the tubing at the zone of sampling.
- Simple configuration
- Easy to run and set up
Glass Flow Cell (Kit RM2)
When a glass flow cell with an expanded ID is used in the sample zone, the highest performance can be obtained.
- Maximum sensitivity can be achieved by a large sample volume.
- Higher rate of flow is possible without signal drop from the T1 and T2 effects.
Figure 3. The two hardware kit options offered by Magritek for reaction monitoring
The Spinsolve® Benchtop NMR Spectrometer has the following applications:
- Determine reaction kinetics
- Optimize yields
- Identify reaction endpoints
- Determine intermediates and by-products
Example: Acetalization of Acetaldehyde
In this organic synthesis, methanol and acetaldehyde produce acetaldehyde dimethyl acetal. As the reaction progresses, it can be precisely and easily monitored by observing the acetaldehyde’s methyl group at 2.25ppm and the acetaldehyde dimethyl acetal’s methyl group at 1.4ppm (Figure 4).
Figure 4. Acetalization of acetaldehyde
This information has been sourced, reviewed and adapted from materials provided by Magritek.
For more information on this source, please visit Magritek.