111 chem 344 organic chemistry lab june 18 th 2008 spectroscopy of organic compounds lecture 3...
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![Page 1: 111 CHEM 344 Organic Chemistry Lab June 18 th 2008 Spectroscopy of Organic Compounds Lecture 3 –Infrared and Mass Spec Nick Hill](https://reader033.vdocuments.net/reader033/viewer/2022042707/5a4d1b5e7f8b9ab0599ac623/html5/thumbnails/1.jpg)
111
CHEM 344Organic Chemistry Lab
June 18th 2008
Spectroscopy of Organic CompoundsLecture 3 –Infrared and Mass Spec
Nick Hill
![Page 2: 111 CHEM 344 Organic Chemistry Lab June 18 th 2008 Spectroscopy of Organic Compounds Lecture 3 –Infrared and Mass Spec Nick Hill](https://reader033.vdocuments.net/reader033/viewer/2022042707/5a4d1b5e7f8b9ab0599ac623/html5/thumbnails/2.jpg)
![Page 3: 111 CHEM 344 Organic Chemistry Lab June 18 th 2008 Spectroscopy of Organic Compounds Lecture 3 –Infrared and Mass Spec Nick Hill](https://reader033.vdocuments.net/reader033/viewer/2022042707/5a4d1b5e7f8b9ab0599ac623/html5/thumbnails/3.jpg)
3
OCPh
H
1703 cm-1
![Page 4: 111 CHEM 344 Organic Chemistry Lab June 18 th 2008 Spectroscopy of Organic Compounds Lecture 3 –Infrared and Mass Spec Nick Hill](https://reader033.vdocuments.net/reader033/viewer/2022042707/5a4d1b5e7f8b9ab0599ac623/html5/thumbnails/4.jpg)
OCEt
HO
1716 cm-1
OCEt
HO
O CEt
OH
2800 - 2600 cm-1
![Page 5: 111 CHEM 344 Organic Chemistry Lab June 18 th 2008 Spectroscopy of Organic Compounds Lecture 3 –Infrared and Mass Spec Nick Hill](https://reader033.vdocuments.net/reader033/viewer/2022042707/5a4d1b5e7f8b9ab0599ac623/html5/thumbnails/5.jpg)
C NPr
2260 cm-1
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M + e [M] + 2 e
Molecular Fragments
Molecule
Molecular Ion
EI
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Mass Spectrum of methanol CH3OH
32
31
29
15
[CH2OH]+
[CHO]+
[CH3]+
[CH3OH]+.
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[M]
Cation stability more important than radical stability
Molecular Ion
A + B
Cation
Radical X
XA + B
Cation
Radical
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C8H18MW = 114
8571
57
43
29
114
C6H13+
C5H11+
C4H9+
C3H7+
C2H5+
Mass Spectrum of octane
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Mass Spectrum of 2,2,4-trimethylpentane
57
43
Me Me
MeMe
Me
MW=114C8H18Me
Me
Me
C
Me
Me H
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Mass Spectrum of 1-butanol
56
OH
MW=74C4H10O
31
43
29
CH2=OH
via loss of H2OCH3CH2
Resonance stabilized
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OH
MW = 88C5H12O
Mass Spectrum of 2-methyl-2-butanol
59
55
73
70
4331CH2=OH
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OH
OH OH
m/ z = 59
- CH2CH3
- H2O
m/ z = 70
OH OH
m/ z = 73
- CH3
Me
m/ z = 55
- CH3
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Mass Spectrum of 2-octanone
OC8H16OMW = 128
113
43
58
O
O
via -cleavage
via -cleavage
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O
O
+
CH3+O
m/z = 43
m/z = 113
Molecular ion m/z = 128
-cleavage at a C=O group
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Mass Spectrum of 2-octanone
OC8H16OMW = 128
113
43 OH
58
O
O
via -cleavage
via -cleavageMcLafferty rearragement
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OH
m/z = 58
+OH
m/z = 128
McLafferty rearrangement of a ketone
1-pentene
O
OH
H OH
OH+
m/z = 60m/z = 88
McLafferty rearrangement of a carboxylic acid
ethene
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Mass Spectrum of Benzamide
10577
44
O
O
NH2
O
NH2
C7H7NOMW=121 121
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19
Mass Spectrum of Toluene
CH3
MW=92C7H8
92
91Loss of H Benzyl cation???
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Tropylium cation m/z = 91
CH3
HH
H
H
HH
H-H
Toluene radical cation m/z = 92
m/z = 91 common to all alkyl benzenes
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Mass Spectrum of 3-methyl-1-butanamine
NH2
MW=87C5H13N
30
CH2=NH2
via-cleavage