Diagnosis: Analysis II

Not Voodoo Home / Comments? / Anatomy of a reaction

A Perfect Reaction (see all): TLC indicates a single product. A crude 1H NMR spectrum indicates only your desired compound with few or no impurities. You can easily identify an optimal method for purification.

A Nightmare Scenario (see all): You can't find your product.

Common Rookie Mistakes: Chromatography Spectroscopy

Step by Step:

  1. TLC the crude product to make sure it matches the reaction mixture. If it does not, see TLC Troubleshooting.
  2. If you do not expect reagent peaks to overwhelm product peaks, take an NMR of your crude reaction mixture after workup.

    Why take a crude NMR or GC?

  3. If you observe two products and can identify them by NMR or GC, record the ratio of the products.
  4. Decide whether the product(s) are worth isolating (see Examples): if so, proceed to Purification.

See also: Rookie Mistakes, TLC How to, 1H NMR How to, Reaction Checklist, Troubleshooting the Experiment