We use cookies to enhance your experience. By continuing to browse this website, you agree to our use of cookies. More information.

Magritek's Spinsolve benchtop NMR spectrometer is a powerful analysis system designed for online NMR reaction monitoring in chemical laboratories. The instrument can be directly installed in the fume hood of the laboratory to check the state of the chemical reaction (Figure 1). With the help of standard PTFE tubing, the reactants can be easily pumped from the reactor to the magnet.

Figure 1. Spinsolve NMR spectrometer installed in a fume hood to monitor batch reactions.

Online NMR reaction monitoring has the following advantages:

Spinsolve NMR spectrometer has the following advantages:

Acetalization is defined as the standard reaction of forming acetals from alcohols and aldehydes. It produces by-product water under the catalysis of acid. The following equation shows how acetaldehyde reacts with methanol to form acetaldehyde dimethyl acetal.

The reaction is carried out in dimethyl sulfoxide (DMSO). First, mix 20 mL of acetaldehyde in 30 mL of DMSO to prevent evaporation. Then, 35 mL of methanol was introduced dropwise into the reactor at a rate of approximately 1 mL min-1. 0.5 mL of hydrochloric acid is used as a catalyst.

Figure 2. The waterfall plot shows the NMR spectrum acquired as a function of time during the reaction.

Then observe the reaction for 1 hour and record the spectrum every 15 seconds, as shown in the waterfall chart (Figure 2). When the purple and green marked areas are combined, the total mass of acetaldehyde dimethyl acetal (purple) and acetaldehyde (green) in the reactor can be measured.

Figure 3-5. The spectrum of the initial mixture (green) shows the signal of acetaldehyde. At the end of the reaction (purple), 4.7 ppm of acetaldehyde dimethyl acetal and water signals can be observed.

The spectrum acquired for the original mixture (green) shows an acetaldehyde signal (2.25 ppm for methyl and 9.7 ppm for carbonyl). At the end of the reaction (purple), 4.7 ppm of acetaldehyde dimethyl acetal and water signals can be observed. The signal from 2.7ppm DMSO does not interfere with the signal of the product or reactant (Figure 3). This reaction does not require deuterated DMSO.

In another example, the reduction of acetophenone (AP) to 1-phenylethanol (PE) is monitored by transfer hydrogenation with isopropanol. At the beginning of the experiment, the reactor contained only isopropanol. After turning on the pump, 2% AP was introduced into the reactor, and then the NMR spectrometer was set to record NMR spectra at standard intervals of 10 seconds.

Figure 6. Reduction of acetophenone (AP) to 1-phenylethanol (PE).

The peak in (a) matches three different isopropanol groups, and the AP signal (blue) is visible after the spectrum is amplified by an order of magnitude (b). Next, the solution was mixed with the iridium catalyst and the reaction was observed for several hours. The final spectrum is shown in Figure (c) (Figure 6). Therefore, it can be concluded that the peaks of 1-phenylethanol (green) and acetone (red) replace the signal from AP.

Figure 7. An enlarged view of the aromatic region of the spectrum.

Figure 8. The change of PE concentration over time, measuring three different concentrations of catalyst.

In addition, the solvent peak does not affect the aromatic region of the spectrum, and the signals can be combined to determine the concentration of PE (from 7.1 to 7.45 ppm) and AP (from 7.85 to 8.3 ppm) (Figure 7). Figure 8 shows the concentration of PE over time, quantifying the catalyst at different concentrations. These results are evaluated with GC, showing that they have good agreement.

These results show that when reactants or products are diluted in a protonated solvent, they can be accurately measured online using a Spinsolve spectrometer installed in a fume hood.

Figure 9 shows a typical setting for online monitoring. First, a Dewar flask with an inner diameter of 2.25 mm and an outer diameter of 5 mm is placed in the hole of the spin dissolution spectrometer, which helps to reduce the heat transfer from the flowing sample to the magnet. Through a 2 mm outer diameter PTFE tube, the reaction mixture is pumped through the hole of the magnet.

The pump is installed behind the magnet to reduce the pipe length L1, and can be set to run in stop-flow mode or continuous mode to reach the point in approximately 15 seconds. In order to ensure the stability of the spin dissolution spectrometer, the temperature of the mixture flowing into the magnet should be kept at 30 °C, but the reaction can be carried out at a temperature of about 100 °C. As the reaction mixture passes along the length of the L1 pipe, the temperature of the reaction mixture will be cooled to 30°C or lower.

Magritek's Spinsolve Carbon benchtop NMR spectrometer is a compact and low-cost instrument that provides excellent sensitivity and unparalleled performance. The device also saves time, space and cost, and is suitable for performing common two-dimensional experiments.

Founded in 2004, Magritek is an advanced technology company that exports from Germany and New Zealand to customers all over the world. The initial technology and IP used in Magritek products were developed by research teams from RWTH University in Germany, Massey University in New Zealand and Victoria University of Wellington.

Today, Magritek provides complete NMR and MRI system solutions for the oil and gas industry, as well as components and subsystems suitable for research laboratories and education.

This information is derived from materials provided by Magritek and has been reviewed and adapted.

For more information on this source, please visit Magritek.

Please use one of the following formats to cite this article in your paper, essay, or report:

Margaretke. (2019, August 21). Use Magritek's Spinsolve to monitor NMR reactions online. AZoM. Retrieved from https://www.azom.com/article.aspx?ArticleID=11357 on December 6, 2021.

Margaretke. "Use Magritek's Spinsolve to monitor NMR reactions online". AZoM. December 6, 2021. <https://www.azom.com/article.aspx?ArticleID=11357>.

Margaretke. "Use Magritek's Spinsolve to monitor NMR reactions online". AZoM. https://www.azom.com/article.aspx?ArticleID=11357. (Accessed on December 6, 2021).

Margaretke. 2019. Use Magritek's Spinsolve to monitor NMR reactions online. AZoM, viewed on December 6, 2021, https://www.azom.com/article.aspx?ArticleID=11357.

Do you have any questions about this article?

AZoM and Professor Guihua Yu of the University of Texas at Austin discussed a new type of hydrogel sheet that can quickly convert contaminated water into pure drinking water. This novel process may have a major impact on alleviating global water shortages.

In this interview, AZoM and Jurgen Schawe from METTLER TOLEDO talked about fast scanning chip calorimetry and its various applications.

AZoM talked with Professor Oren Scherman about his research on a new type of hydrogel that can achieve extreme compressibility under high pressure.

Miniflex XpC is an X-ray diffractometer (XRD) designed for quality control in cement plants and other operations that require online process control (such as pharmaceuticals and batteries).

Raman Building Block 1064 consists of the following necessary components: spectrometer, 1064 nm laser, sampling probe and other optional accessories.

The knife grinder GRINDOMIX GM 200 has two sharp, sturdy blades and a powerful 1000 W motor, making it an ideal instrument for grinding and homogenizing food and feed.

AZoM.com-AZoNetwork website

Owned and operated by AZoNetwork, © 2000-2021