NMR

• Why do we use TMS as a standard solution ?


  Tetramethylsilane :

  1. Only produces one peak
  2. TMS peak won’t interfere with sample peaks
  3. easily removed due to its low boiling point
  4. non-toxic
  5. chemically inert
• What solvent do we use in H1 NMR

  We use a solvent to ensure clear peaks and to use less of out sample:

  • use solvent with no hydrogen atoms (deuterated solvents- solvents that don’t interfere with other peaks)
• Why are CCl3 and CDCl3 used as solvents ?

  Both have no H atoms so give no signals in spectrum

  CCl3 is non polar - good solvent for non-polar organic molecules

  CDCl3 is polar covalent molecule
• What is the n+1 rule

  The peak produced by any given hydrogen environment is split into the number of neighbouring non-equivalent hydrogens +1. Excluding hydrogens bonded to oxygen or nitrogen