AC12: NMR Spec

Question 1

What solvent is used to check if there is a H in a -OH or -NH group and how does this work

Answer 1

deuterium - heavy water
add D2O to sample, H in OH / NH peak disappears.

Question 2

What does NMR stand for

Answer 2

Nuclear Magnetic Resonance

Question 3

Give one use of NMR

Answer 3

MRI scans

Question 4

What kind of nuclei does NMR work with

Answer 4

Those with uneven number of nucleons - proton and 13 carbon

Question 5

What does the area under the peak represent for proton NMR

Answer 5

proportional to the number of proton atoms

Question 6

What is the integration trace in NMR

Answer 6

A stepped line that makes it easier to measure the area under the curve

Question 7

When does splitting/spin-spin coupling occur in NMR

Answer 7

neighbouring Hydrogen atoms (on adjacent atoms) affect the magnetic field of protons and causes their peaks to split

Question 8

What is the n+1 rule in NMR

Answer 8

If there are n inequivalent protons on the neighbouring carbon, then the peak will split into n+1 smaller peaks

Question 9

Why does the peak from O-H or N-H bonds disappear if D2O is used as a solvent

Answer 9

H in O-H / N-H is substituted by D