AS Chemistry A OCR - Organic Analytical Techniques

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  • Created by: Shipreck
  • Created on: 16-02-16 21:54

Infared Spectroscopy

  • Infared Radiation causes bonds to vibrate/stretch more and absorb energy.
  • Atmospheric Gases (CO2, H2O, CH4)
    • Contain C=O, O-H and C-H bonds.
    • Energy absorbtion by these bonds is believed to be the reason for global warming.
    • The reason we use less energy now is because power plants create these atmospheric gases.
  • Infared Spectra
    • Alcohol
      • Peak for the OH bond around 3600
    • Ketone/Aldehyde
      • Peak for C=O around 1700
    • Carboxylic Acid
      • Peak for the broad carboxylic acid OH bond around 3600
      • Peak for the C=O around 1700.
  • IR Spectroscopy is also used for breathalysers 
    • Measured the amount of ethanol in the breath
      • Look for the OH bond and the CH bond groups.
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Mass Spectrometry

  • Molecular Ion Peak (M+) is the peak furthest to the right.
    • Possible M+1 peak due to carbon-13.
  • Limited to Ions with single charges.
  • When fragmentation occurs, they do not reform or recombine.
    • This means that if you have a C2H5+ fragment, somewhere in the structure there is a section that has the formula C2H5.
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