10.1: Organic Structure Determination

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How do we know:

• how atoms are connected together?

• Which bonds are single, double, or triple?

• What functional groups exist in the molecule?

• If we have a specific stereoisomer? The field of organic structure determination attempts to answer these questions.'

INSTRUMENTAL METHODS OF STRUCTURE DETERMINATION

1. Nuclear Magnetic Resonance (NMR) – Excitation of the nucleus of atoms through radiofrequency irradiation. Provides extensive information about molecular structure and atom connectivity.

2. Infrared Spectroscopy (IR) – Triggering molecular vibrations through irradiation with infrared light. Provides mostly information about the presence or absence of certain functional groups.

3. Mass spectrometry – Bombardment of the sample with electrons and detection of resulting molecular fragments. Provides information about molecular mass and atom connectivity.

4. Ultraviolet spectroscopy (UV) – Promotion of electrons to higher energy levels through irradiation of the molecule with ultraviolet light. Provides mostly information about the presence of conjugated π systems and the presence of double and triple bonds.