NMR

Question 1

Describe a use for NMR spectroscopy in medicine.

Answer 1

magnetic resonance imaging/providing diagnostic

information/body scanners.

Question 2

State the region of the electromagnetic spectrum used in 1H NMR spectroscopy.

Answer 2

Radio (waves)

Question 3

Explain why CDCl3 is used as a solvent in 1H NMR spectroscopy.

Answer 3

The solvent does not have any hydrogen/H/protons 

Question 4

The 1H NMR spectrum contains a peak at δ = 0 ppm resulting from a chemical added to the sample.State the chemical responsible for the peak at δ = 0 ppm, and state why this chemical was added to the sample.

Answer 4

TMS/tetramethylsilane

which is the) standard (for chemical shift measurements

Question 5

The 1H NMR spectrum includes an integration trace. What information can be deduced about compound L from the integration trace?

Answer 5

(relative) number of protons/hydrogens in each
environment / peak / region
OR three proton environments with protons in ratio 5:1:6

Question 6

A second proton NMR spectrum of compound F was obtained after adding a few drops of D2O.What difference would you expect to see between the proton NMR spectra of compound F obtained with and without D2O?

Answer 6

peak at  = 11.0 (ppm) disappears 

Question 7

The chemist used both infrared and 13C NMR spectroscopy to identify the two carboxylic acids and to distinguish between them.How do both types of spectra allow the carboxylic acids to be identified and distinguished?

Answer 7

infrared – 1 mark only
shows (very broad) peak between 2500–3300 (cm–1)
(due to O–H bond) 
13C NMR – 2 marks
(CH3)2CHCH2COOH has 4 peaks (due to 4 different
C environments) 
(CH3)3CCOOH has 3 peaks (due to 3 different C
environments) 