TMS is Superior to Residual CHCl3 for Use as the Internal Reference for Routine 1H NMR Spectra Recorded in CDCl3
TMS is Superior to Residual CHCl3 for Use as the Internal Reference for Routine 1H NMR Spectra Recorded in CDCl3
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DOI：
10.1021/acs.joc.1c02590
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发表时间：
2022-01-02
影响因子：
3.6
通讯作者：
Hoye, Thomas R.
中科院分区：
文献类型：
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作者：
Guzman, Alexander L.;Hoye, Thomas R.
早在60多年前，四甲基硅烷就被推荐作为质子核磁共振波谱的内参化合物。然而，通常的做法是，研究人员将分析物的化学位移与记录光谱的氘化溶剂中的残余质子共振联系起来。由于CDCl3是有机化合物常规分析中最常用的核磁共振溶剂，因此各种官能团对CHCl3共振的影响非常重要。这里描述的结果表明，为什么参考光谱TMS而不是CDCl3中的CHCl3导致更准确的化学位移，应该是推荐的做法。使用同心管布置同时测量未受扰动的CDCl3/TMS与CDCl3/TMS/溶质溶液的分离区室是关键。之所以在这里报道这项研究，是因为听众/读者是相当合适的，希望他们既能接受也能欣赏所提供的指导。
Tetramethylsilane was recommended for use as an internal reference compound in proton NMR spectroscopy over 60 years ago. However, it is a common practice that researchers reference the analyte chemical shifts to the residual proton resonance in the deuterated solvent in which the spectrum is recorded. Because CDCl3 is the most commonly used NMR solvent for routine analysis of organic compounds, the effect of various functional groups on the CHCl3 resonance is important. Described here are results that show why referencing spectra to TMS rather than CHCl3 in CDCl3 results in more accurate chemical shifts and should be the recommended practice. Simultaneous measurement of separate compartments of unperturbed CDCl3/TMS vis-a-vis CDCl3/TMS/solute solutions using a concentric tube arrangement was key. This study is reported in this venue because the audience/readership is quite appropriate and is, hopefully, both receptive to and appreciative of the guidance provided.