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Isomers of Pentanol and Pentene with FTIR Analysis
Chemistry 233L/234L
Dr. Gergens - SD Mesa College
Name:_______________________________
Part I - Draw out all isomers of C 5 H12 O and pentene (C5 H10 ).
A. Write out the line-angle formula and give the I.U.P.A.C. name for all isomers of pentanol (C5 H12 O). Organize
the isomers from decreasing parent chain length starting with n-pentanol. Finally, label each carbon
atoms by letter, and give equivalent carbon atoms the same letter. Use the examples as guidelines.
b
a
d
c
e
OH
b
OH
a
c
d
b
e
a
b
c
a
OH
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1.
How many pentanols are primary, secondary, and tertiary? 1° ____, 2° ____, 3° ____ alcohols
2.
How many pentanols have two magnetically equivalent methyl— branches in its structure ____, and
give their IUPAC name:
3.
How many pentanols have three magnetically equivalent methyl— branches in its structure ____, and
give their IUPAC name:
4.
How many pentanols have two magnetically equivalent ethyl— branches in its structure ____, and
give their IUPAC name:
5.
How many pentanols are optically active having chiral centers ____, and give their IUPAC name:
B. Write out the line-angle formula and give the common name for all isomers of ethers with the formula (C5 H12 O).
Organize the isomers from decreasing parent chain length starting with methyl n-butyl ether.
Finally, label each carbon atoms by a letter with equivalent carbon atoms given the same letter as done in the
pentanol problem.
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6.
How many ethers have the alkyl branch in its common name? methyl ____, ethyl ____, propyl ____,
isopropyl ____, n-butyl ____, sec-butyl ____, isobutyl ____, and t-butyl ____.
7.
How many ether have not more than two magnetically equivalent methyl groups in its structure 2, and give their
common name:
8.
How many ethers have three magnetically equivalent methyl— branches in its structure ____, and
give their common name:
9.
How many ethers are optically active having chiral centers ____, and give their IUPAC name:
C. Write out the line-angle formula and give the I.U.P.A.C. name for all isomers of pentene (C5 H10 ). Organize the
isomers from decreasing parent chain length starting with 1-pentene. Finally, label each carbon atoms
by a letter with equivalent carbon atoms given the same letter as done in the pentanol problem.
Name:
Name:
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10. How many pentene are cis, trans, and neither? cis ____, trans ____, neither ____
11. How many alkenes have two magnetically equivalent methyl— branches in its structure ____, and
give their common name
Part II - FTIR Analysis of Isomers of C 5 H12 O and Pentene
12. Go to the link and review Dr.Gergens' Tutorial - Fundamentals of Infrared Spectroscopy for infrared analysis.
http://www.ilcmesa.sdccd.cc.ca.us/Depts/Chemistry/spectroscopy_links.htm
13. Identify and name each compound 1, 2 and 3. Give definitive frequency regions, IR absorbencies or the absence of
IR absorbencies which you would use to clearly distinguish between them. Briefly explain your reasoning.
CH3CH2CH2CH(OH)CH3
1
CH3OCH2CH2CH2CH3
2
trans CH3CHCHCH2CH3
3
14. Go to the spectroscopy links page for the course,
http://www.ilcmesa.sdccd.cc.ca.us/Depts/Chemistry/spectroscopy_links.htm
and select the link below for the SDBS (Japanese site) HNMR - CNMR - MS spectra search for Organic Compounds
http://www.aist.go.jp/RIODB/SDBS/menu-e.html
This spectroscopy site will be used extensively throughout the semester to obtain spectroscopy data.
Search by molecular formula for compound 1, 2 and 3. Seaching by molecular formuala will give the broadest
database search results.
Obtain the FTIR spectrum for each compound 1, 2 and 3. Match your results to the spectra given on the next
page.
15. Match the FTIR spectra with compounds. All six spectra are printed on the same scale.
CH3CH2CH2CH(OH)CH3
1
3000
2000
1500
1000
500 4000
3000
3000
2000
1500
1000
500 4000
3000
C
4000
3000
2000
2000
1500
1000
500
1500
1000
500
1500
1000
500
E
B
4000
3
D
A
4000
trans CH3CHCHCH2CH3
CH3OCH2CH2CH2CH3
2
2000
F
1500
1000
500 4000
3000
2000
16. Was matching FTIR spectra in question 15 an easy task? Select your best answer.
A.
B.
C.
D.
F.
Forget it, I do not like doing FTIR analysis, and I did not take the time to review Dr. Gergens' on it.
No, I am not very good at doing FTIR analysis. Perhaps, I should seek additional help from the instructor.
So, so. I feel I am not very good at doing FTIR. Perhaps, I should review Dr. Gergens' FTIR tutorial again.
Somewhat, I was able to identify the six spectra as being two spectra as alcohols, two as ethers, and two as
some type of hydrocarbon, perhaps the alkene. However, I am not sure between how to tell each two apart, so I
made a logical guess between the two in matching. Heck, 50/50 chance at getting it right.
Yes, I was able to separate each spectra as one of three possible functional groups; alcohol, ether, or alkene
(hydrocarbon). Then between the two spectra of the same functional group, an educated guess was made as to
which compound it could be. A IR spectra data base linked to our course home page was used to search on
molecular formulas given in the problem. The database search produced a extensive list of possibilities, but from
the most appropriate molecular name for each formula, the search was narrowed. Direct comparison of the
FTIR's in this assignment to that of the actual spectra in the database allowed for a definite match.