Basics of NMR

When one is interested in determining the structure of organic compounds by NMR, one must be able to extract from the spectrum all the information that will allow the construction of the structural formula of a compound with a known gross formula or the confirmation of the structural formula of a compound. The NMR measurements observed in an isotropic solvent are chemical shifts and scalar couplings: their relative amplitudes, at first approximation, determine the fact that the spectrum can be interpreted in the 1^st order or the 2^nd order in a given magnetic field. The relative areas of the signals (or integrals) make it possible to determine the quantitative composition of the sample.

Important information to be extracted for the interpretation of a spectrum:

• Chemical shift δ (ppm)
• Scalar coupling constants J(Hz) and multiplicity (singlet, triplet, doublet of doublets…)
• 1^st or 2^nd order spectra?
• Relative signal integrations