Organic Structure Elucidation

ACS In Focus Organic Structure Elucidation assists readers in developing the chemical logic required to interpret analytical data for the structural elucidation of small organic molecules.

When presented with a compound, whether it be a completely unknown substance, an expected product from a reaction, or an unexpected by-product, spectral data is used to elucidate the exact structure unambiguously. In this process, not only is confidence given to a structural claim, but in doing so, other proposed structures can be refuted.

The general principles of structural elucidation are similar across various fields within chemistry, so the details presented herein are broadly applicable. This primer focuses on elucidating organic compounds, and three main spectrometric techniques will be explored: infrared spectroscopy (IR), mass spectrometry (MS), and nuclear magnetic resonance spectroscopy (NMR). Some non-spectrometric aspects of structure elucidation will be described initially, including molecular formula, degree of unsaturation, and isomers, as they are used throughout any further analyses. Some specific spectrometric techniques, along with the relevant equations used in IR and NMR, help the reader to see the importance of how light is used to cause a specific transition in a molecule. Then each of the three techniques will be described in detail including how and why it works, what spectra look like, and the relevant factors that determine how data is analyzed.

Within these chapters, one example compound will be analyzed so the reader can get a complete picture of structure elucidation. Lastly, the closing chapter will present relevant examples of the power of the techniques learned in this primer as applied to specific aspects of structure elucidation.

The primer includes links to many free online web-based resources for readers to access in their practice of structure elucidation. It is through the continual practice of “putting it all together” that the skill set for figuring out structures is increased.