Structure determination

Structure determination

1. Mass spectrometry

   • Base peak - the highest peak caused by the most abundant ion
   • Molecular ion peak - the one on the right - the Mr - position depends on m/z
   • Molecular fragments - M+e- = M+. +2e-
   • Only X+ will be accelerated the radical wont be

2. n.m.r

   • Odd mass number nuclear will spin with the magnetic field or opposed to it
   • Chemical shift - size of the shift compared to the standard TMS

3. Proton n.m.r

   • Atoms in the same chemical environment are described as equivalent atoms
   • Stronger electronegativity pull electrons towards it and expose the nucleus deshielding the H atoms
   • Integration value is the number of protons
   • Furthest to the left - arger chemical shift are most desheilded

4. Peak splitting

   • Protons in neighbouring chemical environments are coupled
     • One will have spin aligned with the field and be slightly desheidled and visa versa
   • Look at non-equivielnt group next to it - n+1 rule

5. Carbon n.m.r

   • Draw circle around groups - join like groups with a line

6. Chromatography

   • Column
     • Different compounds in a mixture are eluted by a solvent
     • Retention time - time taken to leave the column - depends on attraction to stationary phase and solubility to mobile phase
   • Gas-liquid
     • Separate volatile liquids
     • Long coiled tube so fits into an oven
     • Stationary phases the liquid with the higher boiling point, mobile phase is unreactive gas
       • Sample vaporises and pushed through by the carrier gas - different components emerge depending on boiling points