Application Note 2: Benchtop NMR
Spectroscopy Without Deuterated
Solvents
Most discussions on proton NMR spectroscopy are based on the fact that spectra are
typically recorded in solutions prepared with deuterated solvents. The reason for this isthat a protonated solvent will give rise to large solvent peaks which may obscure spectralfeatures of the solute. Furthermore, most modern NMR spectrometers rely on the solvent’s
deuterium signal for shimming and locking. Although there are certain advantages inusing proton-free solvents, it may be desirable to examine a reaction or a product in its
native solution. The Magritek Spinsolve benchtop NMR spectrometer uses a fast external
lock and does therefore not require deuterated solvents for high-resolution performance.
In this note, we show some representative examples of proton NMR spectra recorded infully protonated solvents.

Deuterated Solvents
Introduction

Most discussions on proton NMR spectroscopy are based on the fact that s
recorded in solutions prepared with deuterated solvents. The reason for thi
protonated solvent will give rise to large solvent peaks which may obscureof the solute. Furthermore, most modern NMR spectrometers rely on the sosignal for shimming and locking. Although there are certain advantages insolvents, it may be desirable to examine a reaction or a product in its nativ
The Magritek Spinsolve™ benchtop NMR spectrometer uses a fast externa
therefore not require deuterated solvents for high-resolution performance.
show some representative examples of proton NMR spectra recorded in fusolvents.

IBUPROFEN

Ibuprofen

Two samples of a 200 mM solution of ibuprofen in chloroform were prepa
deuterated and one in a protonated solvent. Spectra were recorded with theof the 1D Proton protocol. Figure 1 shows the spectra for both samples.

Two samples of a 200 mM solution of ibuprofen inchloroform were prepared, one in deuterated and one
in a protonated solvent. Spectra were recorded with
the Quickscan option of the 1D Proton protocol.
Figure 1 shows the spectra for both samples.

Figure 1

Apart from the large solvent peak at 7.3 ppm, the spectrum with the non-dealso shows two smaller peaks, which are not present for the deuterated solv
to the solvent protons coupling to the small quantity of connected 13C nucl
abundance of 13C is 1.1%, and the intensity of these so-called satellite peakmain peak. Although the solvent peak overlaps with peaks 4 and 5 of the sspectral features can be resolved very clearly.

Figure 1: NMR spectrum of 200 mM Ibuprofen in CHCl3 (red) and in CDCl3(blue).
Figure1: NMR spectrum of 200 mM Ibuprofen in CHCl3 (red) and in CDCl3 (blue). Although the solvent peakoverlaps with peaks 4 and 5 of the solute, all other spectral features can be resolved very clearly.

Nitration of Acetanilide
NITRATION OF ACETANILIDEIn this second-year chemistry experiment, students synthesis
nitration of acetanilide.

In this second-year chemistry experiment, students
synthesise p-nitroacetanilide through the nitrationof acetanilide.

NHCH3ONH

H2SO4HNO3O-+N

CH3OO

Figure 2

Figure 2 shows the NMR spectra of starting material (red) an
deuterated and non-deuterated DMSO. Although there is a lasolvent, all peak assignments can still be made for the molec

Figure 2: NMR spectra of 200 mM acetanilide (red) and p-nitroacetanilide in
deuterated and non-deuterated DMSO.

Figure 2: NMR spectra of 200 mM acetanilide (red) andp-nitroacetanilide (blue) in deuterated and non-deuterated DMSO.

Caffeine
A sample of caffeine dissolved in water was taken from a chromatographic column forCAFFEINEA sample of caffeine dissolved in water was takenfrom a chromatographic column for benchtop NMR
analysis.

No further sample processing or purification wasrequired. The proton NMR spectrum is shown in
Figure 3.
Figure 3: Measured
NMR spectrum ofcaffeine in H2O (blue)
as taken from a
HPLC column, andthe simulated NMR
spectrum of themolecule (red).

Figure 3

Figure 3: Measured NMR spectrum of caffeine in H2O (blue) as taken from aHPLC column, and the simulated NMR spectrum of the molecule (red).

Figure 3: Measured NMR spectrum of caffeine in H2O (blue) as taken from a
HPLC column, and the simulated NMR spectrum of the molecule (red).

Conclusions
Conclusion

The Spinsolve benchtop NMR spectrometer has been used to record proton NMR spectra indeuterated
and non-deuterated
solvents.
there may behasa slight
disadvantage
in theTheSpinsolvebenchtop
NMRAlthough
spectrometerbeenused torecord proton NMR spectra in deuterated
large solvent peak obscuring peaks of the solute, the vast benefit in using non-deuterated
andnon-deuterated
Althoughthere maya nativeslightsolution.
disadvantage in the large solvent peaksolvents
is that reactions andsolvents.
reagent solutions
can be routinely
studiedbe
in theSuch
issues,aswellasrunning
costs,
becomeimportant
when
using
benchtopNMR
as
an onobscuring peaks of the solute, the vast benefit in using non-deuterated
solvents is that reactions andline
monitoring tool.
Conclusions
reagent solutions can be routinely studied in the native solution. Such issues, as well as running costs,
The Spinsolve benchtop NMR spectrometer has been used to record proton NMR spectra inbecome important when using benchtop NMR as an on-line monitoring tool.
deuterated and non-deuterated solvents. Although there may be a slight disadvantage in thelarge solvent peak obscuring peaks of the solute, the vast benefit in using non-deuterated
solvents is that reactions and reagent solutions can be routinely studied in the native solution.
Such issues,
as well as running costs, become important when using benchtop NMR as an onCONTACTINFORMATION
line
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