No-D NMR (No-Deuterium Proton NMR) spectroscopy: A simple yet powerful method for analyzing reaction and reagent solutions

Organic Letters

Volumn 6, Issue 6, 2004, Pages 953-956

  Hoye, Thomas R ^a   Eklov, Brian M ^a   Ryba, Troy D ^a   Voloshin, Mikhail ^a   Yao, Letitia J ^a  

^a University of Minnesota   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ALKENE; DEUTERIUM; LITHIUM DERIVATIVE; PROTON; REAGENT; SOLVENT; TETRAHYDROFURAN;

ARTICLE; CHEMICAL REACTION; ESTERIFICATION; LITHIATION; PROTON NUCLEAR MAGNETIC RESONANCE; QUANTITATIVE ANALYSIS; TECHNIQUE;

DEUTERIUM; INDICATORS AND REAGENTS; MAGNETIC RESONANCE SPECTROSCOPY; PROTONS; SOLUTIONS;

EID: 1642528338     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol049979+     Document Type: Article

References (20)

1. 2 Moreover, although more specialized applications in various areas (e.g., LC NMR, food science, mechanistic studies, MRI, oil and petroleum industries, and quality control) can be found, use by preparative organic chemists is not at all routine.
2. 1H NMR data set!"
3. Solvent suppression routines were not used for any of the spectra shown here. However, particularly for more dilute samples, they can lead to better spectral quality. Another contributing factor to routinely achieving the quality of the spectra presented here is that most modern NMR spectrometers suffer very little from magnet drift and, therefore, give narrow lines when run in unlocked mode.
4. Fischer, E.; Speier, A. Ber. Dtsch. Chem. Ges. 1895, 28, 3252-3257.
5. All spectra shown here were recorded on a Varian INOVA 500 instrument, but the technique is applicable to any spectrometer. Factors influencing instrument choice for No-D experiments are no different than those for conventional locked mode acquisition.
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13. 1/2 = 1.78 h at 20°C).
14. 1H NMR spectrum. Select, expand, and note a "reporter resonance" of known peak shape (a solvent peak is usually a good choice, but any peak of known multiplicity will suffice). Run the FID/Spectrum macro 〈gf〉 and enter the interactive acquisition display process 〈acqi〉 (to allow observation of the real-time FID or spectrum). (e) Shimming using the FID. After performing the initial setup, select the FID button and then increase the gain until the FID level is between 500 and 1000 (to allow easier observation of small changes in the FID level). Adjust the shims, allowing the FID level to stabilize before making each additional adjustment, until a maximum FID level (numerical) has been achieved. (f) Shimming using the Spectrum. Shim by monitoring the increase in reporter peak intensity (numerical and/or graphical) and peak symmetry. Don't be discouraged by initial poor-looking peak shape. In general, note that the response to a change in shim settings will occur more slowly here than it will when shimming on a deuterated sample in locked mode. The process of shim optimization is otherwise quite analogous for samples in nondeuterated vs deuterated solvents. Once the shims are optimized, exit "acqi" and take another one pulse spectrum. If the overall spectrum quality is acceptable, proceed with recording the spectrum. Shimming the second through the nth sample at the same sitting will usually be easier.
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20. m resonances integrated reliably to 1.00 ± 0.02.