Nuclear Magnetic Resonance Spectroscopy (NMR)

Question 1

What scale is used for recording chemical shift?

Answer 1

δ scale in parts per million

Question 2

What does the chemical shift depend on?

Answer 2

The molecular (hydrogen or carbon) environments

Question 3

In high resolution nmr, what are the different types of peaks you can get?

Answer 3

Singlet, duplet, triplet and quartet

Question 4

What is the name of the standard used?

Answer 4

(TMS) Tetramethylsilane- Si surrounded by 4 methyl groups

Question 5

Why is TMS a suitable standard for NMR?

Answer 5

• Inert and highly volatile
• Has 12 H atoms in one environment and 4 C atoms in one environment, so it gives one strong signal outside the range of most other molecules

Question 6

What solvent is typically used in nmr and why?

Answer 6

CCl₄, because it is inert

Question 7

What rule is used in H n.m.r. to determine the splitting of peaks?

Answer 7

The ‘n + 1’ rule in which the number of splits in the peaks is determined by the number of hydrogens in the neighbouring environment. (+1)

Question 8

What is needed to determine the relative numbers of equivalent protons in the molecule?

Answer 8

Integration data

Question 9

Which type of n.m.r. gives a simpler spectrum, H n.m.r of ¹³C n.m.r?

Answer 9

¹³C n.m.r