NMR Spectroscopy Flashcards
What is NMR Spectroscopy?
An analysis technique that you can use to work out the structure of an organic molecule.
How does NMR work?
1) A sample of a compound is placed in a strong magnetic field and exposed to a range or different frequencies of low energy radio waves.2) The nuclei of certain atoms within the molecule absorb energy from the radio waves.3) The amount of energy that a nucleus absorbs at each frequency will depend on the environment that it’s in.4) The pattern of these absorptions gives you information about the positions of certain atoms within the molecule, and about how many atoms of that type the molecule contains.5) Piece all this together to work out the structure.
What are the two types of NMR I need to know about?
Carbon- 13 NMR- gives you information about the number of carbon atoms that are in the molecule, and the environments that they are in.High resolution proton NMR gives you the information about the number of hydrogen atoms that are in the molecule, and the environments that they’re in.
What different ‘environments’ affect the amount of energy that nuclei absorb?
Being partly shielded from the effects of external magnetic fields by its surrounding electrons.Any other atoms/groups of atoms surrounding the nucleus will also affect the amount of electron shielding.
What is used as standard in NMR?
Tetramethylsilane
NMR spectroscopy definition
Involves the interaction of materials with the low energy radio-wave region of the electromagnetic spectrum.
NMR uses
-Used to determine the structure of a compound -Same technology used to obtain images of soft body tissue, very useful as it is non-evasive and the low energy radio-waves do not damage body tissues.-Used when looking at substances at crime scenes, and in airport/ border security.
C-13 NMR two main features
-The position of the peaks i.e the chemical shift value = identifies the type of ‘C-C’ -number of the peaks = number of different ‘C-C’ environments
