NMR signals provide information based on 3 separate features of the peak:

• The Chemical Shift, or where along the x-axis the signal is located. This is measured in δ, ppm downfield from the reference compound Me₄Si; this tells us about the chemical environment--what groups might be bonded to the carbon bearing the observed hydrogen nucleus.
• The integral, or the relative area under the peak (including all legs of any multiplet; this tells us how many hydrogens are located in symmetry-equivalent positions.
• The coupling pattern, which is determined by (and can be back-interpreted to reveal) the structural relationship to nearby hydrogens (or other NMR-active nuclei--fluorine, for example).

Select an NMR peak in the spectrum of methylphenylketone (marked in red along the top) to highlight the nuclei responsible for it in the structure to the right. grid on grid off show peak list Selections off

Look at several different molecules with different functional groups. Be sure to load the spectrum by clicking on the name before zooming/highlighting.
1-Hexene The sp² region is downfield. If you zoom in, each of the three vinyl protons is distinguishable, though for the two terminal signals, parts of the multiplet overlap. The alkyl regiion (upfield) is straightforward.
Benzaldehyde The downfield singlet is the CHO proton, not coupled (too far from other protons). The aromatic ring protons have more complex coupling in part due to the impact of the aldehyde conjugation.
Benzoic Acid The O-H peak broadens due to H-bonding and is often hard to find if it flattens out along the baseline; it's not seen in this spectrum.
1-Methylcyclopentanol The O-H peak is downfield; this can be narrow or broad depending on concentration, temperature or small amounts of acid (common in CDCl₃, the normal NMR solvent). The adjacent protons are diastereotopic (cis/trans to the OH) and at different chemical shifts. The C-3 and C-4 protons are also diastereotopic, but the chemical shift difference is too small to distinguish.
Phenylethyne The alkyne proton shows an anisotropy that is actually shielding and pushes it upfield (we'd expect it to be >10 based on electronegativity arguments).
Hexanenitrile An example of how electronegative groups diminish in their effect down the chain.
Ethyl Acetate Ethyl groups are common enough that you should begin to recognize and immediately interpret the classic "triplet + quartet" pattern.
n-Butylamine A good example of the kind of broadening seen in H-bonding groups.

Note that you may also view ¹³C spectra. Load the molecule, right-click the spectrum, choose "Spectra" and select spectrum 1.3, labeled "13CNMR...". Be sure to deselect any other spectra.

Normal modes calculated at the B3LYP/6-31G** level and assigned based on the calculated spectrum using Gaussian09. Gaussian 09, Revision D.01, M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, Ö Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, and D. J. Fox, Gaussian, Inc., Wallingford CT, 2009.
¹H NMR spectra were taken either from the PLU spectral archive, or simulated based on data reported in the AIST Spectral Database for Organic Compounds.
Page last updated: 3/31/2015