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Chemistry LibreTexts

4.19: Appendix

  • Page ID
    194913
  • Table of 13C NMR Frequencies Common in Organic Compounds.

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    Note that effects are additive: two or more electron-withdrawing groups move the absorbance further to the left than just one group.

    Table of 1H NMR Frequencies Common in Organic Compounds.

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    This chart shows the frequancies of protons that are attached to carbons. In general, protons follow the trend seen in the carbon to which they are attached. Note again the additive effects of multiple attached groups.

    This table does not include OH (or NH) protons. Protons attached to heteroatoms are more difficult to pinpoint because their locations in the spectrum are much less specific. Instead, they may be found across a very broad range.

    Table of 1H NMR Frequencies of OH Common in Organic Compounds.

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    Table of Some Common Impurities in NMR Samples.

    Minor impurities in the NMR spectrum are often the result of solvents used during a reaction or sample purification. A few examples are provided in the following table, showing the data you would see from common solvents in an NMR spectrum taken in chloroform.

    solvent number of peaks shift multiplicity integral ratio assignment
    water 1 1.56 br. s - O-H
    acetone 1 2.17 s - (C=O)CH3
    chloroform 1 7.26 s - Cl3C-H
    t-butyl methyl ether 2 1.19 s 3 C(CH3)3
    3.22 s 1 O-CH3
    ethyl acetate 3 1.26 t 3 CH2CH3
    2.05 s 3 (C=O)CH3
    4.12 q 2 OCH2CH3
    grease or alkanes 2 0.86 m varies; smaller CH2CH3
    1.26 m varies; larger CH2CH2CH2 / CH2CH2CH3

    An excellent table, including shifts of a variety of impurities in different NMR solvents, can be found in the following article: Gottlieb, H. E.; Kotlyar, V.; Nudelman, A. J. Org. Chem. 1997, 62, 7512-7515.

    Table of Solvent

    Residual Peaks

    Because an NMR sample is mostly solvent (with a small amount of dissolved solute that you are really interested in), there is usually a peak in the spectrum that comes from atoms in the solvent. Usually the use of deuterated solvents (enriched in 2H instead of 1H) minimizes the size of solvent peaks in 1H NMR. However, there is always a trace of 1H left in the solvent, which shows up as a small peak in the spectrum. 13C residual peaks are often much larger than the peaks arising from the solute.

    Solvent 1H Shift Multiplicity 13C Shift Multiplicity*
    Acetone-d6 2.05 pent 206.68 sing
    29.92 sept
    Acetonitrile-d3 1.94 pent 118.69 sing
    1.39 sept
    Benzene-d6 7.16 sing 128.39 trip
    Chloroform-d 7.27 sing 77.23 trip
    D2O 4.80 --
    Dichloromethane-d2 5.32 trip 54.00 pent
    DMF-d7 8.03 sing 163.15 trip
    2.92 pent 34.89 sept
    2.75 pent 29.76 sept
    DMSO-d6 2.50 pent 39.51 sept
    Methanol-d4 4.87 sing 49.15 sept
    3.31 pent
    THF-d8 3.58 sing 67.57 pent
    1.73 sing 25.37 sing

    *Note that coupling to 2H produces different patterns than coupling to 1H.