111 CHEM 344 Organic Chemistry Lab June 18 th 2008 Spectroscopy of Organic Compounds Lecture 3...
-
Upload
melanie-wright -
Category
Documents
-
view
217 -
download
0
description
Transcript of 111 CHEM 344 Organic Chemistry Lab June 18 th 2008 Spectroscopy of Organic Compounds Lecture 3...
111
CHEM 344Organic Chemistry Lab
June 18th 2008
Spectroscopy of Organic CompoundsLecture 3 –Infrared and Mass Spec
Nick Hill
3
OCPh
H
1703 cm-1
OCEt
HO
1716 cm-1
OCEt
HO
O CEt
OH
2800 - 2600 cm-1
C NPr
2260 cm-1
M + e [M] + 2 e
Molecular Fragments
Molecule
Molecular Ion
EI
Mass Spectrum of methanol CH3OH
32
31
29
15
[CH2OH]+
[CHO]+
[CH3]+
[CH3OH]+.
[M]
Cation stability more important than radical stability
Molecular Ion
A + B
Cation
Radical X
XA + B
Cation
Radical
C8H18MW = 114
8571
57
43
29
114
C6H13+
C5H11+
C4H9+
C3H7+
C2H5+
Mass Spectrum of octane
Mass Spectrum of 2,2,4-trimethylpentane
57
43
Me Me
MeMe
Me
MW=114C8H18Me
Me
Me
C
Me
Me H
Mass Spectrum of 1-butanol
56
OH
MW=74C4H10O
31
43
29
CH2=OH
via loss of H2OCH3CH2
Resonance stabilized
OH
MW = 88C5H12O
Mass Spectrum of 2-methyl-2-butanol
59
55
73
70
4331CH2=OH
OH
OH OH
m/ z = 59
- CH2CH3
- H2O
m/ z = 70
OH OH
m/ z = 73
- CH3
Me
m/ z = 55
- CH3
Mass Spectrum of 2-octanone
OC8H16OMW = 128
113
43
58
O
O
via -cleavage
via -cleavage
O
O
+
CH3+O
m/z = 43
m/z = 113
Molecular ion m/z = 128
-cleavage at a C=O group
Mass Spectrum of 2-octanone
OC8H16OMW = 128
113
43 OH
58
O
O
via -cleavage
via -cleavageMcLafferty rearragement
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
Mass Spectrum of Benzamide
10577
44
O
O
NH2
O
NH2
C7H7NOMW=121 121
19
Mass Spectrum of Toluene
CH3
MW=92C7H8
92
91Loss of H Benzyl cation???
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
Mass Spectrum of 3-methyl-1-butanamine
NH2
MW=87C5H13N
30
CH2=NH2
via-cleavage