9/5/24

Question 1

In the absence of other protons and at the start of a tree diagram, how does the proton appear?

Answer 1

as a singlet

Question 2

what causes a proton to spilt its signal

Answer 2

the presence of other neighboring protons and their affect on the protons experienced magnetic field

Question 3

What is the coupling constant

Answer 3

it describes the strength of the nuclei interactions with eachother

if it is large, it means the protons have a larger effect on eachothers magnetic fields

Question 4

what will we see if the coupling constants are equal?

Answer 4

the n+1 rule will apply and we will see a conjoining of protons to create a large peak

Question 5

what will we see if the coupling constants are not the same

Answer 5

the n+1 rule will not apply and we will see second order coupling

Question 6

what is spin spin coupling

Answer 6

it describes the affect that non-equivalent protons on adjacent carbons have on a proton signal. These protons may align or oppose the applied field and can affect the chemical shift of the peak and cause a spiltting affect

Question 7

When a neighboring proton is in its Beta spin state, how does it affect the main proton?

Answer 7

it causes a spilt in the upfield direction since the magnetic field experienced is lower

Question 8

when a neighboring proton is in its alpha spin state, how does it affect the main proton

Answer 8

it causes the experienced magnetic field to be higher and causes a spilt in the downfield direction

Question 9

what is the coupling constant of a cis coupling

Answer 9

10 Hz

Question 10

what is the coupling constant of trans coupling

Answer 10

15 Hz

Question 11

what is the coupling constant of geminal coupling

Answer 11

2 Hz

Question 12

what does a large coupling constant mean

Answer 12

it means there is a better interaction between the magnetic fields of the nuclei

Question 13

what is the difference that causes a signal to be a doublet of doublets or a triplet

Answer 13

a triplet is seen when the coupling constants are the same, a doublet of doublets is caused by unequal coupling constants

Question 14

what can experience a proton transfer

Answer 14

a proton connected to a electronegative atom

Question 15

what is a method of proton transfer

Answer 15

deuterium exchange

Question 16

what is a deuterium exchange

Answer 16

it allows you to exchange the protons on a electronegative element with deuterium

Question 17

what happens to the O-H signal when it undergoes a deuterium exchange?

Answer 17

the peak disappears because the NMR only sees protons

Question 18

if you have an OH group, and a HA nearby, would the OH appear as a neighbor for signal spiltting?

Answer 18

no, the proton transfer occurs so quickly that the NMR does not detect a spiltting so it is ignored at room temperatures

Question 19

if you wanted to see an OH as a neighbor, what would you have to do to the NMR?

Answer 19

you would need to run the NMR in cool temperatures to slow down the proton exchange

Question 20

why is a C13 NMR hard to conduct

Answer 20

only 1.1% of carbons are C13, so it is harder to do a C13 NMR and it takes more time and concentrations