ABSTRACT
Nuclear magnetic resonance (NMR) spectroscopy is the most powerful spectroscopic method for structural elucidation of organic molecules and is routinely used by organic chemists. This chapter summarizes the common NMR active nuclei; chemical shift data for NMR solvents, common impurities and functional groups; coupling constants; and details of common NMR experiments used to determine the connectivity and stereochemistry of small organic molecules. Vicinal coupling constants are reduced by electronegative substituents and reduced as the length of the carbon–carbon bond increases. Modern NMR experiments are used extensively for structure elucidation. Solvent suppression is an experiment for reducing the signal intensity associated with non-deuterated solvents and allowing the acquisition of 1D spectra. Selective total correlation spectroscopy (TOCSY) is an experiment showing all the signals in a spin system that exhibit through-bond scalar coupling, starting from the selectively excited signal. The attached proton test (APT) is an experiment for assigning multiplicities to signals in decoupled 13C spectra.
