1. Mass Spectroscopy
Chapters 7, 8, and 9

2. Mass Spectrum Diagram

3. Electron Source for Electron Ionization (EI)
Ions travel to detector

4. Example of Fragmentation

5. EI and CI Comparison
Electron Impact Ionization
Chemical Ionization

6. Fast Atom Bombardment

7. What ions do the following mass represent?
Analysis of Propene
What ions do the following mass represent?
1) 42 m/z
41 m/z
42 m/z
2) 41 m/z
27 m/z
15 m/z
3) 27 m/z
4) 15 m/z

8. Analysis of 2-Methylhexane
What ions do the following mass represent?
1) 100 m/z
43 m/z
2) 43 m/z
3) 41 m/z
85 m/z
41 m/z
100 m/z
4) 85 m/z

9. Useful Tables from Your Book
pg. 260

10. Match Spectra with Compound
Spectra A
Spectra B
Spectra A
Spectra B

11. Match Spectra with Compound1. 2.
43 m/z
55 m/z
71 m/z
85 m/z
42 m/z
84 m/z 3.
57 m/z
56 m/z
Spectra 2
Spectra 1
41 m/z
Spectra 3

12. Isopropylbenzene 105 m/z 120 m/z 77 m/z What ions are the following?
Benzyl cation!
2) 77 m/z
1) 105 m/z

13. What is the likely Structure of the Following Aromatic Molecule?
C10H14
119 m/z
MW = 134 m/z
MW = 134 m/z
77 m/z
119 m/z
Why not ?
105 m/z

14. EI-MS of Triethylamine
What is 86 m/z?
86 m/z
MW =101 m/z
(Notice odd #)

15. What is the Major Fragment?
58 m/z
58 m/z

16. Methyl 2-phenylethyl ether
45 m/z
What is the ion corresponding to the following mass?
91 m/z
45 m/z
136 m/z
What does 91 m/z correspond to?

17. Ethyl tert-pentyl ether
What are the ions corresponding to the following masses?
87 m/z
1) 101 m/z
101 m/z
2) 87 m/z

18. What are the ions corresponding to the following masses?
3,3-Dimethyl-2-Butanol
What are the ions corresponding to the following masses?
57 m/z
45 m/z
1) 45 m/z
87 m/z
102 m/z
2) 57 m/z
3) 87 m/z

19. Bromobenzene and Chlorobenzene
77 m/z
112 m/z
158 m/z
156 m/z
77 m/z
114 m/z
MW 77 m/z appears on both spectra. What ion corresponds to 77 m/z?
77 m/z

20. 1-halo-3-methylbutanes
43 m/z
43 m/z
70/71 m/z
70/71 m/z
For all spectra, what ions corresponds to 71 m/z? What about 43 m/z? See if you can figure out the halogen for each spectra too!
43 m/z
71 m/z
43 m/z
71 m/z
FYI: 70 m/z (loss of H from 71 m/z)

21. 2-Heptanone 43 m/z 58 m/z 99 m/z 114 m/z
What ions correspond to the following masses?
(McLafferty Rearr.)
1) 43 m/z
2) 99 m/z
3) 58 m/z

22. 5-methyl-2-hexanone 43 m/z 58 m/z 71 m/z 114 m/z
What ions correspond to the following masses?
(McLafferty Rearr.)
1) 43 m/z
2) 71 m/z
3) 58 m/z

23. Octanal 44 m/z 29 m/z What ions correspond to the following masses?
(McLafferty Rearr.)
1) 29 m/z
2) 44 m/z

24. o-Methylbenzaldehyde
91/92 m/z
120/119 m/z
What ions correspond to the following masses?
1) 92 m/z
2) 119 m/z

25. Octanoic Acid 60 m/z 73 m/z 101 m/z 115 m/z
What ions correspond to the following masses?
(McLafferty Rearr.)
1) 60 m/z
2) 73 m/z
3) 115 m/z

26. 4-Ethylbenzoic Acid 105 m/z 150 m/z 135 m/z 76 m/z
What ions correspond to the following masses?
Even mass to even mass =
2 bonds broken! But not McL Rearr.
1) 105 m/z
2) 135 m/z
3) 76 m/z

27. Ethyl Hexanoate 88 m/z 99 m/z 60 m/z 73 m/z
What ions correspond to the following masses?
(McLafferty Rearr.)
(McLafferty Rearr.)
4) 60 m/z
1) 99 m/z
2) 88 m/z
3) 73 m/z
4 bonds broken

28. Match the Constitutional Isomers (MW = 144) with their Mass Spectrums
102 m/z B
74 m/z
71 m/z
87 m/z B
74 m/z A
102 m/z

29. Match the Constitutional Isomers (MW = 143) with their Mass Spectrums
59 m/z B
87 m/z
72 m/z
100 m/z A
59 m/z B
87 m/z

30. Exact Mass of Common Elements

31. Find the Molecular Formulas from the Exact Mass
m/z
C8H13N2
m/z
C4H5NO2
m/z
C10H20O

32. Determine the Structure of the Molecule
Exact Mass:
= C8H10
:p = 4 (4 rings/double bonds)
91 m/z
77 m/z
91 m/z
106 m/z
77 m/z
106 m/z