Intrumental analysis (summaries of 2.8)

Question 1

How do we use IR spectroscopy?

Answer 1

Peak at a specific wave number —> check IR absorption values in d.b.

Question 2

How do we work out the molecular mass of a compound using a mass spectrometer?

Answer 2

The molecular mass of the compound is the peak furthest to the right (the molecular ion peak)

Question 3

What do we do with to work out the fragments on a mass spectrometer?

Answer 3

Working out their m/z values lets you identify them
e.g - CH3+ = 15

Question 4

How do we use 13C NMR spectroscopy?

Answer 4

1. Number of peaks = number of carbon environments
2. Use data sheet to assign chemical shift values to 13C environments
3. Draw all possible structural isomers. Identify the number of 13C environments in each structure.

Question 5

How do we use 1H NMR spectroscopy?

Answer 5

1. Number of peaks = number of proton environments
2. Ratio of the number of protons in each environment (from the formula)
3. From this ratio, work out the number of protons in each environment
4. Use chemical shifts to work out the types of proton