¹H NMR Spectra and Chromotography

Use of High-Resolution ¹H NMR Spectra in Structure Elucidation

  • Chemical Shift (δ): Gives information on the environment of protons.

  • Integration: Indicates the relative number of protons in a given environment.

  • Spin-Spin Coupling: Determines connectivity between protons (e.g., singlet, doublet, triplet).

  • Multiplicity (n+1 rule): Predicts splitting pattern based on neighbouring protons.

  • Combined with Other Spectroscopy Techniques: IR (functional groups), MS (molecular mass), ¹³C NMR (carbon environment).

(g) Use of Chromatographic Data (TLC, Paper Chromatography, GC, HPLC) to Find Composition of Mixtures

  • TLC/Paper Chromatography:

    • Separates based on polarity and adsorption onto a stationary phase.

    • Uses Rf values for identification.

  • Gas Chromatography (GC):

    • Separates volatile compounds based on boiling points and interactions with a stationary phase.

    • Retention times are used for identification.

  • High-Performance Liquid Chromatography (HPLC):

    • Separates based on interactions with a high-pressure liquid phase.

    • Used for non-volatile or thermally unstable compounds.