Green Chemistry with Benchtop NMR

Green Chemistry is the composition of novel approaches to reduce the hazards for human health and environmental waste in chemical synthesis.¹ Thus, the methodologies developed focus on minimizing by-products and solvents that pose harm to humans and the environment. As benchtop NMR does not require cryogens, it is an excellent instrument to support the principles of green chemistry. Our spectrometers reduce the exposure and expense of liquefied gases (such as nitrogen and helium) utilized mostly in high-field NMR.

One principle of green chemistry is developing methodologies that focus on atom economy. Atom economy as the name suggests aims to maximize all the reagents used in the final product of a reaction, thus limiting by-products. Solvent-free reactions are another component of green chemistry that highlights modern approaches to traditional procedures. These approaches avoid the need for solvents through processes of grinding with a mortar and pastel, irradiation through sonication or microwaves, or utilization of catalytic reagents.² Combining these principles with benchtop NMR, allows for certain products to be potentially analyzed as neat (depending on the sample) or in greener solvents (e.g., water, methanol, or acetone). Furthermore, the purity of chemical reactions can be analyzed to ensure quality of the desired product.

To illustrate chemical reactions with principles of green chemistry we have used the following mechanism with the product characterized by benchtop NMR (¹H, ¹³C, and HSQC):

Scheme 1. Reaction scheme for the formation of 1,1-diethyl-3(4-methoxybenzyl)urea.³

Figure 1. ¹H (59 MHz), ¹³C (15 MHz), HSQC (¹H: 61 MHz, ¹³C: 15 MHz) NMR spectra of 1,1-diethyl-3(4-methoxybenzyl)urea, in CDCl₃. Structure of the product is denoted with labeled protons (green) and labeled carbons (blue)

This short and simple synthesis can be implemented in organic chemistry labs on a small scale to demonstrate atom economy, and the use of greener solvents. Green chemistry allows for every chemist to contribute to a framework of minimizing the overall environmental footprint.⁴ Our instruments can also be placed in a fume hood, allowing for more toxic reactions to remain in a limited space which reduces exposure of these samples to the chemist. If you have any questions on how our instruments can be implemented in your applications, please don’t (scan) delay contacting us. Thank you!

References

[1] Ivanković, A., Dronjić, Bevandaand A. M., and Talić S. International Journal of Sustainable and Green Energy. 2017, 6(3): 39-48

[2] Banik, B. K., et al. Molecules (Basel, Switzerland) 2021, 26(4): 1163

[3] Karche, A. D., et al. Organic Process Research & Development 2022, 26(11): 3141-3152

[4] Ganesh, K. N., et al. Organic Process Research & Development 2021, 25(7): 1455-1459