12. Nuclear magnetic resonance in fuel analysis

Question 1

In Nuclear Magnetic Resonance (NMR) spectroscopy, specifically proton NMR, the peaks in the spectrum correspond to different types of hydrogen atoms (protons) in a molecule.

Answer 1

true

Question 2

NMR measurements can not performed for what nuclei?

Answer 2

That are non-magnetic, Nuclei with an even number of protons and an even number of neutrons

Question 3

Nuclei with an odd number of protons and an odd number of neutrons. Are these nuclei NMR active or not?

Answer 3

active, but in practice NMR spectra are measured only for
nuclei with I (nuclear spin) = 1/2.

Question 4

What info chemical shift provides?

Answer 4

they inform about the chemical environment of the measured
nucleus

Question 5

each type of nucleus (for 1H e.g., CH3
, CH2
, H on a double bond, aromatic H) has its own
characteristic region in the spectrum where its signals occur.

Answer 5

true

Question 6

What are two ways of measuring NMR spectra?

Answer 6

By applying a high-frequency electromagnetic field to the sample (continuous wave spectrometry)
or by pulse NMR spectrometry

Question 7

The measurement of NMR in solution is the most common method

Answer 7

true

Question 8

The sample (For measurement in solution) must be dissolved in a suitable deuterated solvent. What can be the solvent?

Answer 8

acetone (CD3COCD3
)
* chloroform (CDCl3
)
* dichloromethane (CD2Cl2
)
* toluene (C6D5CD3
)
* water (D2O)
* tetrahydrofuran (C4D8O)
* ethanol (C2D5OD)
* methanol (CD3OD

Question 9

What are two-dimensional measurements used for in NMR?

Answer 9

These techniques are mainly used for distinguishing isomers, i.e., for
detailed analysis.