NMR 3.3.15 in papers 2 + 3
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why is TMS a suitable standard?
• strong signal at 0ppm • its inert • has 12H so has a very identifiable peak
what is a chemical shift?
the change in nucleus resonance frequency due to its surronding electron cloud
what does the number of signals tell us?
how many different types of H there is in a molecule
what does the position of the signals tell us?
what kind of proton is present
what does the intensity of the signals tell us?
the number of protons in an environment
what does the number of peaks tell us?
• number of protons in the adjacent carbon • number of splits = number of adjacent protons + 1
why IS Si(CH3)4, CCl4 and CDCl3 used in 1H NMR spectroscopy?
• CDCl3 or CCl4 solvent • TMS as reference • Inert • Both have no H • CCl4 non polar • CDCl3 polar covalent molecule TMS as reference 12H to give one signal • Signal in an area away from other typical H signals • Easy to remove