6.3 - Analysis Flashcards
What can NMR spectroscopy tell us
Types of carbon environment
Types of environment (chemical shift)
Relative no. of these diff types of carbon (integration/strength)
Integration of carbon environment
Depends on height
Ratio of height matches ratio of carbon environment
Chemical environment
Diff bonds and atoms surrounding a nucleus
Why isn’t C-12 used in NMR
Has an even mass no. so there’s no overall spin
Not NMR active
When is the chemical shift greater
More electron deficient the carbon
More deshielded the nucleus
Which solvent is used in NMR
Liquid CDCl3 as deuterium (2-H) has an even mass no. and no overall spin so the C-13 peak is easily identified and removed
What is used as the reference peak
Tetramethylsilane (TMS)
Why is TMS used as the reference peak
Produces strong single peak
Chemical shift defined at zero
Peak found at far right of spectrum
Scale increases from right to left
Aromatic environment
How many of the carbon environments are part of the aromatic ring
H NMR
Uneven mass no. so NMR active
Requires solvents w/out H or w/ D
Why can’t organic solvents be used in H NMR
Contain C and H atoms which will produce NMR signal
Relative peak areas in H NMR
Shows relative no. of protons on each environment
Stationary phase in TLC
Silica gel plate
Mobile phase in TLC
Solvent
What may give diff compounds sim Rf values
Same functional group
