IR, NMR Flashcards
What does an IR do
Shows the presence or absence of functional groups in a molecule.
What does NMR do
Show the interelated connectivity of Hydrogen and carbon atoms.
How does an IR work
the chemical bonds in the molecule absorb different amounts of infared energy.
What are the four types of information that can be extraced from H NMR
- Number of different kinds of protons
- Integration
- Chemical shift
- Spin-spin coupling
How to know how many kinds of protons there are in an H NMR
The number of groups of signals is how many kinds of protons
What is integration
a way to count the number of protons in each group
how to do integration (H NMR)
look at the integration values, and compare them relative to eachother.
What is TMS
tetramethylsilane - used in NMR’s as point 0
what is chemical shift of an H NMR
it shows the electron density around the H.
Explain how chemical shift works
the closer the H is to an electronegative substance, the more it will be deshielded, and will shift downfield. the further the H is from the electronegative substance the more shielded it will be and the further upfield it will stay
What is spin-spin coupling
it shows how many protons are on adjacent atoms.
You look at the splitting of each peak, and subtract one from the number of peaks. That tells you how many H’s are on adjacent atoms.
OH peaks
do not typically couple with adjacent atoms
What is CDCL3
it’s deuterated chloroform. It’s the preferred solvent for C NMR’s. It’s peak is always 77 ppm
What does the splitting on C NMR tell you
how many H’s that carbon is attached to
Where on the IR can you find alcohols ( R-O-H)
3600 - 3200
