Agriculture Reference
In-Depth Information
Hexanoic acid
120
100
80
O
60
C
O
OH
40
C
20
0
4000
3500
3000
2500
2000
1500
1000
Wavenumber cm
-1
Octene Octyne 1-Hexanol
120
100
80
CC
60
H
C
OH
40
H
CC
20
0
4000
3500
3000
2500
2000
1500
1000
Wavenumber cm
-1
Figure 8.11.
Infrared spectra showing common absorption. Both the OH of acids and alcohols
are hydrogen-bonded, lending to broadening of the absorption. Note that the OH absorption of
hexanol is unusually sharp for a hydrogen-bonded alcohol.
8.11.1.
Infrared Sample Preparation
All compounds have absorptions in the midinfrared region of the spectrum.
Most common solvents contain groups that absorb in this region of the spec-
trum, which are important for identification of unknowns and thus are not
used. Carbon tetrachloride, carbon disulfide, and mineral oil (often called
nujol
) are exceptions, in spite of the fact that all three have significant infrared
absorbences. Mineral oil, for example, has strong absorbences due to —CH
3
,
—CH
2
— in its molecules. This obscures regions that may be of analytical
