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FTIR Report
Fourier-Transform Infrared Spectroscopy Report on Unknown #22
Daniel Monticue
CHEM 231L
Dr. Gergens
March 19, 2019
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Conclusion
Unknown number 22 was an alcohol and was correctly identified as 3-methyl-3-pentanol.
The sample, prepared neat, gave off a most distinctive FTIR spectral reading. It showed a broad, moderate stretch
at 3383.24 cm-1, which is characteristic of an O-H group. This, along with the fact that there were no observed C=O
absorbancies, ruled out carboxylic acid and ruled in alcohol. The absence of C=O also ruled out any esters,
ketones, and aldehydes, amides. In addition, the C-O stretch reflected a 1156.27 cm-1 frequency, consistent with a
tertiary alcohol (1205-1124cm-1). This could easily rule out 1-butanol which is a primary alcohol and would instead
show an absorbance between 1085-1050 cm-1. This absorbancy also lacked any double or triple bond peaks which
ruled out cyclohexene, bromobenzene, 1-pentene, toluene, or phenetole. The primary determining factor in
identifying the unknown as 3-methyl-3-pentanol was the broad, moderate stretch at 3383 cm-1 characteristic of an
O-H absorbancy. Once identified, the fingerprint region of the experimental unknown was carefully compared to
that of the actual FTIR for 3-methyl-3-pentanol referenced on the SDBS website1 which confirmed that unknown
sample number 22 was indeed identified as 3-methyl-3-pentanol.
Ref:
1. https://sdbs.db.aist.go.jp/sdbs/cgi-bin/landingpage?sdbsno=4588
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Correlation Table
Specific Functional Group
Observed Frequency Vibration (cm–)
Intensity
Shape
O-H
3383.24
Moderate
Broad
C-H
~2960
Strong
Sharp
CH2
1459.51
Moderate
Sharp
CH3
1377.92
Moderate
Sharp
C-O
1156.27
Moderate
Sharp
Experimental FT-IR Spectrum – 3-Methyl-3-Pentanol Sample Ran Neat
Actual FT-IR Spectrum* - 3-Methyl-3-Pentanol
*Source: https://sdbs.db.aist.go.jp/sdbs/cgi-bin/landingpage?sdbsno=4588