Organic Chemistry I Lab
CHEM 2211L (Fall 2008)
School of Science & Technology
Georgia Gwinnett College
Experiment G. Spectroscopy: Mass Spectroscopy (MS),
Infrared Spectroscopy (IR), Ultraviolet-Visible Spectroscopy
(UV-Vis), Nuclear Magnetic Resonance Spectroscopy (NMR)
______________________________________________________
1. EXPERIMENTAL OBJECTIVES: The purpose of this experiment is to
a. learn to use the FTIR and UV-Vis instrumentation in the lab.
b. access and analyze spectra on web databases.
c. integrate analysis of MS, IR, UV-Vis, and NMR to determine structure of
unknown compounds.
d. present, analyze, discuss results in written report.
2. SPECIAL INSTRUCTIONS:
a. There is no pre-lab quiz . You will not do a lab report in your lab notebook,
but instead turn in the lab procedure pages with your solutions to the unknown
compounds, plus your print outs from web databases.
b. While each student turns in their own report, you are encouraged to work
together to solve the unknown structures.
c. Report is due at the end of the second lab period.
d. Chemicals:
(1) benzoic acid, [65-85-0]
(2) methylbenzoate, [93-58-3]
3. PROCEDURES:
(4) 1. Visit the National Institute of Standards and Technology (NIST) (http://nist.gov/)
webpage. Browse to familiarize yourself with how it is organized. Go to the NIST
Chemistry WebBook (http://webbook.nist.gov/), which contains chemical information on
thousands of compounds. Search by CAS (Chemical Abstract Services) Registry
Number: 78-77-3 and find IR (gas), MS, and UV/Vis spectra. Note that NIST provides
the structure for the molecule. Print out a large MS and IR spectrum in the landscape
format. Conduct an analysis of the IR and MS of the known compound using the format
below. This should be straight-forward for the known compound and will serve as a
check of the process before you move on to unknowns.
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Organic Chemistry I Lab
CHEM 2211L (Fall 2008)
School of Science & Technology
Georgia Gwinnett College
a. Molecular weight.
b. All possible molecular formulas and degree of unsaturation of each possibility.
c. Possible functional groups present from IR analysis, consistent with molecular.
formula and degree of unsaturation.
d. Possible fragments lost from the molecular ion.
e. Put together the “puzzle pieces”: rule out or confirm possible molecular
formulas, degrees of unsaturation, and propose consistent pieces of the molecule.
How can they fit together?
f. Proposed structure. Argue convincingly that all of the data supports and confirms
your proposal.
(4) 2. Conduct a web search of the Spectral Database for Organic Compounds SDBS,
(http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/cre_index.cgi?lang=eng), agree to the
disclaimer, and you will arrive at the SDBS Compounds and Spectral Search page.
Search by name for 1-bromo-2-methylpropane and find IR, MS, 1H NMR, and 13C NMR
spectra. Print the chemical information and all four spectra (use the IR in CCl4) and the
accompanying peak data, as appropriate. Conduct an analysis of the known compound
using the format below. This analysis should be straightforward for the known
compound and will serve as a check of the process before you move on to unknowns.
a. Molecular weight.
b. All possible molecular formulas and degree of unsaturation of each possibility.
c. Possible functional groups present from IR analysis, consistent with molecular
formula and degree of unsaturation.
d. Possible fragments lost from the molecular ion.
e. Put together the MS and IR “puzzle pieces”: rule out or confirm possible
molecular formulas, degrees of unsaturation, and propose pieces of the molecule
consistent with the data. How can they fit together?
f. Analyze the 1H NMR spectrum relative to MS and IR spectra.
1)
2)
3)
4)
# of peaks ↔ # of non-equivalent protons.
splitting pattern ↔ # of equivalent adjacent protons (n+1 rule).
chemical shift ↔ functional group.
integrated peak area ↔ relative # ratio of types of protons.
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Organic Chemistry I Lab
CHEM 2211L (Fall 2008)
School of Science & Technology
Georgia Gwinnett College
g. Analyze the 13C NMR spectrum relative to MS and IR spectra.
1) # of peaks ↔ # of non-equivalent carbon atoms.
2) chemical shift ↔ functional group.
3) splitting pattern ↔ # of protons on that carbon atom (n+1 rule).
h. Propose a structure. Argue convincingly that all of the data supports and
confirms your proposal.
(36) 3. Determine the structures of 6 of the 7 unknowns, A-G, in the Appendix. Use the
same analysis protocol you use in 4.a.-h. above, to include f.1)-4) and g.1)-3). Show all
your work directly on the page provided. Be concise but thorough.
(3) 4. IR analysis (solid). Under the guidance of your professor, you will run, print, and
analyze the IR spectrum of benzoic acid.
(3) 5. IR analysis (liquid). Under the guidance of your professor, you will run, print,
and analyze the IR spectrum of methylbenzoate.
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Organic Chemistry I Lab
CHEM 2211L (Fall 2008)
School of Science & Technology
Georgia Gwinnett College
Appendix: Unknowns A-G
Solve the structure of 6 of the following 7 unknown compounds, A-G. Each unknown presents, in order,
elemental analysis followed by mass, IR, 1H NMR, and 13C NMR spectra. Show all your work in the space
provided. Include a structure and name of the unknown in your solution.
Compound A. Elemental Analysis: C, 62.04; H, 10.41; O, 27.55
C NMR Spectral Data:
singlet, 206.0 ppm
quartet, 27.0 ppm
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Organic Chemistry I Lab
CHEM 2211L (Fall 2008)
School of Science & Technology
Georgia Gwinnett College
Compound B. Elemental Analysis: C, 15.40; H, 3.23; contains halogen.
C NMR Spectral Data:
quartet, 17.7 ppm
triplet, 0.4 ppm
13
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Organic Chemistry I Lab
CHEM 2211L (Fall 2008)
School of Science & Technology
Georgia Gwinnett College
Compound C. Elemental Analysis: C, 90.51; H, 9.49.
C NMR Spectral Data:
singlet, 140.2 ppm
doublet, 128.4 ppm
doublet, 127.9 ppm
13
doublet, 125.7 ppm
triplet, 31.1 ppm
quartet, 16.1 ppm
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Organic Chemistry I Lab
CHEM 2211L (Fall 2008)
School of Science & Technology
Georgia Gwinnett College
Compound D. Elemental Analysis: C, 64.02; H, 4.48; contains halogen.
C NMR Spectral Data:
singlet, 133.8 ppm
doublet, 129.9 ppm
doublet, 128.9 ppm
doublet, 126.6 ppm
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Organic Chemistry I Lab
CHEM 2211L (Fall 2008)
School of Science & Technology
Georgia Gwinnett College
Compound E. Elemental Analysis: C, 59.96; H, 13.42; O, 26.62. The molecular ion (m/e = 60) does not
appear in the mass spectrum of this compound.
C NMR Spectral Data:
doublet, 64.9 ppm
quartet, 26.3 ppm
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Organic Chemistry I Lab
CHEM 2211L (Fall 2008)
School of Science & Technology
Georgia Gwinnett College
Compound F. Elemental Analysis: C, 78.65; H, 8.25; O, 13.10.
C NMR Spectral Data:
singlet, 140.2 ppm
doublet, 128.4 ppm
doublet, 127.9 ppm
13
doublet, 125.7 ppm
triplet, 68.5 ppm
triplet, 44.6 ppm
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Organic Chemistry I Lab
CHEM 2211L (Fall 2008)
School of Science & Technology
Georgia Gwinnett College
Compound G. Elemental Analysis: C, 30.29; H, 2.54; contains halogen. Note that long-range coupling
with J  2 Hz is visible in the 1H NMR.
C NMR Spectral Data:
doublet, 68.1 ppm
singlet, 80.3 ppm
triplet, 22.6 ppm
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