NMR Flashcards
What is the standard?
Tetramethylsilane TMS, Si(CH3)4
How do the different peaks come about?
Chemically equivalent hydrogen atoms are all in the same chemical environment and appear at the same chemical shift. A hydrogen atom in a chemical environment has its nucleus exposed.
What does deshielded mean?
The further away the bonded electrons are from the proton the more deshielded the proton. This is caused from being attached to a very electronegative atom.
Why is TMS used?
It has 12 hydrogen environments which are all chemically equal which produce a single peak. The hydrogens are less deshielded than any other H atoms in an organic compound, wont interfere with the other peaks and its inert.
What is the label for the horizontal axis?
Chemical shift 𝞭, and has units ppm
What does the sets of peaks equal?
The number of hydrogen environments
What does the area under each peak equal?
The ratio of the number of hydrogens in each chemical environment
What is the n+1 rule?
The spin-spin splitting pattern is caused by hydrogen atoms bonded to adjacent carbon atoms
What is the difference between low and high resolution?
Low resolution does not show splitting pattern, High resolution does show the splitting pattern
Where do the peaks occur if the hydrogen atoms are bonded to very electronegative atoms?
Are deshielded and appear more downfield
Where do peaks occur if the hydrogen atoms are in alkyl groups?
Less deshielded and appear more upfield.
