Spectroscopy

Question 1

What is NMR spectroscopy?

Answer 1

interaction of a nucleus (odd number of nucleons) with a strong magnetic field and low energy radio frequency radiation where sample dissolved in CDCl3 so not contaminated with 1H peaks

Question 2

What is the reference?

Answer 2

tetramethylsilane aka TMS at 0ppm which has a single intense peak of 12H atoms (it’s the standard)

Question 3

what are the uses of NMR spectroscopy?

Answer 3

used in MRIs to obtain diagnostic information about internal structures.

Question 4

rules in 13c NMR

Answer 4

• symmetry=1 line
• closer to C=O means C-C closer to the LHS
• count no. of peaks to find no. of carbon environment

Question 5

what can be deduced from the integration trace in 1H?

Answer 5

tells you the relative ratio number of H’s

Question 6

what does the splitting pattern tell you?

Answer 6

how many non-equivalent H atoms there are on the neighbouring atoms uses n+1 rule where a triplet (3 peaks) mean n=2 (so when looking at the peaks take 1 off to know the no. of H atoms)
singlet,doublet,triplet,quartet,pentent and multiplet

Question 7

how do you remove problematic OH/NH peaks in 1H?

Answer 7

add D2O to sample resulting in proton exchange where OH/NH peak disappears

Question 8

rules in 1H

Answer 8

• add TMS at 0ppm
• add number of H on top of peaks of neighbouring H peak (peak is no. of neighbouring H’s the H is the number of H’s that is next to those neighbouring H atoms)
• reference the ppm