ir spectroscopy

• OH alcohols are very broad and are further to 3000
• OH acids are very broad, but with C-H signals so making the bumpy and closer to 3000
• C=O are often narrow but very strong and are to the left side of the peak
• C=C bonds are narrow, quite small and on the right side of 1750
• the basics of inra-red spectroscopy

  • the frequencies at which they vibrate are in the infra-red region of the electromagnetic spectrum
  • if the ir light is passed through the compound, it will absorb some or all the light at the frequencies at which the bond vibrates
  • the IR light is measured in wavenumbers 1/frequency
• basics of IR spectroscopy

  • all bonds vibrate at a characteristic frequency ( stretching, contracting aswell as bending vibrations are the common types)
  • the frequency depends on the mass of the atoms in the bond , the bond strength and the type of vibration
• two main things you need to do with the infra-red spectra

  1. use the finger print region
  2. identify functional groups
• using the finger print region

  • below 1500cm
  • complicated and contains many signals
  • used to identify compounds as its unique for every compound
  • used to check is a compound is pure to check if theyre identical