Premium
Monitoring chemical reactions by low‐field benchtop NMR at 45 MHz: pros and cons
Author(s) -
Silva Elipe Maria Victoria,
Milburn Robert R.
Publication year - 2016
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.4189
Subject(s) - chemistry , cons , analytical chemistry (journal) , environmental chemistry , computer science , programming language
Monitoring chemical reactions is the key to controlling chemical processes where NMR can provide support. High‐field NMR gives detailed structural information on chemical compounds and reactions; however, it is expensive and complex to operate. Conversely, low‐field NMR instruments are simple and relatively inexpensive alternatives. While low‐field NMR does not provide the detailed information as the high‐field instruments as a result of their smaller chemical shift dispersion and the complex secondary coupling, it remains of practical value as a process analytical technology (PAT) tool and is complimentary to other established methods, such as ReactIR and Raman spectroscopy. We have tested a picoSpin‐45 (currently under ThermoFisher Scientific) benchtop NMR instrument to monitor three types of reactions by 1D 1 H NMR: a Fischer esterification, a Suzuki cross‐coupling, and the formation of an oxime. The Fischer esterification is a relatively simple reaction run at high concentration and served as proof of concept. The Suzuki coupling is an example of a more complex, commonly used reaction involving overlapping signals. Finally, the oxime formation involved a reaction in two phases that cannot be monitored by other PAT tools. Here, we discuss the pros and cons of monitoring these reactions at a low‐field of 45 MHz by 1D 1 H NMR. Copyright © 2015 John Wiley & Sons, Ltd.