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A LevelChemistryCIERevision Notes8. Analysis (A Level Only)8.1 Analytical Techniques (A Level Only)8.1.6 Use of Tetramethylsilane (TMS)

Use of Tetramethylsilane (TMS) (CIE A Level Chemistry)

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Use of Tetramethylsilane (TMS)

  • In NMR spectroscopy, Tetrametylsilane (TMS) is used as a reference compound
  • The organic compound is dissolved in TMS before being introduced to the magnetic field of the spectrometer
  • It is an ideal chemical to use as a reference
    • TMS is inert and volatile
    • This reduces undesirable chemical reactions with the compound to be analysed
    • It also mixes well with most organic compounds

  • TMS gives a single sharp peak on the NMR spectrum and is given a value of zero
  • The molecular formula of TMS is Si(CH3)4
    • There are 12 hydrogens in this molecule
    • All of the protons are in the same molecular environment. Therefore gives rise to just one peak
    • This peak has a very high intensity as it is accounting for the absorption of energy from 12 1H nuclei

Tetramethylsilane (TMS) – Si(CH3)4

  • When peaks are recorded from the sample compound, they are measured and recorded by their shift away from the sharp TMS peak
  • This gives rise to the chemical shift values for different 1H environments in a molecule

 

Analytical Techniques - TMS 1H NMR, downloadable AS & A Level Chemistry revision notes

 1H NMR spectrum for TMS showing it’s signal at 0 ppm

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    Francesca

    Author: Francesca

    Expertise: Head of Science

    Fran studied for a BSc in Chemistry with Forensic Science, and since graduating taught A level Chemistry in the UK for over 11 years. She studied for an MBA in Senior Leadership, and has held a number of roles during her time in Education, including Head of Chemistry, Head of Science and most recently as an Assistant Headteacher. In this role, she used her passion for education to drive improvement and success for staff and students across a number of subjects in addition to Science, supporting them to achieve their full potential. Fran has co-written Science textbooks, delivered CPD for teachers, and worked as an examiner for a number of UK exam boards.