09/3/24

Question 1

if the relative area of the NMR peaks does not amount to the proton count, what might that mean about the compound?

Answer 1

it might mean that there is symmetry in the molcule, there may be homotopic hydrogens, or enantiotopic hydrogens that give us the same peak

Question 2

what does the decoupled section of a CNMR tell us

Answer 2

it tells us that there is one peak per carbon, the peaks are singlets and the protons are erased

Question 3

what does phase down mean on a DEPT CNMR spectra?

Answer 3

it means a CH2 group

Question 4

what phase does up mean on a DEPT CNMR spectra

Answer 4

it means a CH3 or CH group

Question 5

what are the 4 pieces of information that we can take from an NMR

Answer 5

1. the number of signals tells us how many unique hydrogens we have
2. chemical shift, this tells us the electron density around a proton
3. multiplicity, this tells us how many neighbors we have
4. area, this tells us the relative amount of protons in a peak

Question 6

what are the types of hydrogens that can affect the signals given on an NMR?

Answer 6

homotopic hydrogens
enantiotopic hydrogens
hetereotopic hydrogens
diastereotopic hydrogens

Question 7

how do you know if hydrogens are homotopic?

Answer 7

when preforming the substitution test, if the hydrogens do not form enantiomers or diastereomers but rather give the same molecule, they are homotopic hydrogens

Question 8

how do you know if hydrogens are heterotopic

Answer 8

when preforming the substitution test, if the hydrogens form different molecules that are not enantiomers or diastereotmers, they are heterotopic

Question 9

what is an enantiotopic hydrogen?

Answer 9

when preforming the substitution test, if the replaced substituents form enantiomers, they give rise to the same signal and the NMR sees no difference between the two

Question 10

what is a diastereotopic hydrogen?

Answer 10

when preforming the substitution test, if the replaced substituents form diastereomers, they give rise to the different signals and the NMR sees a difference between the two

Question 11

what is a tree diagram?

Answer 11

it shows how a singlet signal is spilt into multiple signals through interactions with the neighboring proton’s magnetic field

Question 12

what do the larger peaks mean in a spilt signal?

Answer 12

it describes the joining of two spilt signals

Question 13

if you have two hydrogens on a double bond, are they enantiotopic, heterotopic, homotopic, or diastereotopic

Answer 13

if you replace the hydrogens with a halogen, you will get a diastereomer (E/Z or Cis/Trans)