NMR

• What type of technique is NMR spectroscopy?

  Analytical technique
• What does NMR spectroscopy allow to be determined?

  The structure of a molecule

  
• What is analysed to determine the structure of a molecule using NMR spectroscopy?

  The energy of each bond environment
• What do different bond environments within a molecule absorb?

  Different amounts of energy
• How are different bond environments shown on a spectra print out?

  As different peaks
• What are bond environment peaks measured against?

  A standard molecule
• What is the standard molecule used in NMR spectroscopy?

  Tetramethylsilane (TMS)

  
• What is the chemical formula for TMS?

  Si(CH​3​)​4

  
• Why is TMS used as a standard molecule?

  It contains four identical carbon and hydrogen environments
• What ∂ value is TMS seen as on the x-axis?

  ∂=0 ppm
• What does C​13​ NMR spectroscopy analyse?

  Different carbon environments
• How are different carbon environments shown in C​13​ NMR?

  As peaks at different ∂ values
• What do the heights of the peaks in H​1​ NMR spectra show?

  The relative intensity of each ∂ value

  
• What do the relative intensities in H​1​ NMR correspond to?

  The number of hydrogens
• What do the peaks of a H​1​ NMR spectra also inform?

  Where each environment is positioned

  
• What do peaks split into in H​1​ NMR?

  A small cluster
• What do the smaller peaks in H​1​ NMR indicate?

  How many hydrogens are on the adjacent carbon

  
• What is the splitting pattern in H​1​ NMR?

  The amount of peaks
• What rule does the splitting pattern follow?

  ‘n+1’ rule
• What does 'n' stand for in the 'n+1' rule?

  The number of hydrogen
• What does a doublet mean in H1 NMR?

  1 H on adjacent carbon
• What does a singlet mean in H1 NMR?

  No H on adjacent carbon
• What does a triplet mean in H1 NMR?

  2 H on adjacent carbon
• What does a quartet mean in H1 NMR?

  3 H on adjacent carbon
• How are carbon environments near oxygen shifted?

  Shifted to the right
• Why do carbon environments near oxygen have ∂ values shifted to the right?

  Oxygen is very electronegative
• What may molecules with symmetry display?

  Fewer ∂ peaks
• What should you look at to decipher the structure of a compound with symmetry?

  The molecular formula
• How many carbon atoms does 1,2-cyclohexanediol contain?

  Six carbon atoms
• How many peaks does the NMR spectrum of 1,2-cyclohexanediol have?

  Three peaks

  
• Where are all C​13​ NMR ∂ shift values given?

  AQA Chemistry Data Sheet
• What does H​1​ NMR analyse?

  Different hydrogen environments
• What should samples being analysed be dissolved in?

  A non-hydrogen-containing solvent
• Why must the solvent not contain hydrogen?

  So that it doesn’t produce any ∂ peaks
• What is a common solvent used?

  CCl​4
• What is deuterium?

  An isotope of hydrogen
• What does a triplet-quartet splitting pattern represent?

  A -CH​2​-CH​3​ fragment
• What can multiple fragments be pieced together to determine?

  The full molecule structure
• What does NMR spectroscopy measure to determine the structure of a molecule?

  The energy of each bond
• What do the peaks on the NMR spectrum represent?

  Different bond environments