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Name: CHEM 344 Fall 2014
Spectroscopy Problem Set
TA:
Due at start of discussion Monday/Tuesday the 22nd/23rd September
1) Assign all of the integrated signals in the 1H-NMR spectrum of the crude reaction
mixture from the aerobic oxidation reaction shown below. Use the standard labeling (Ha,
Hb, Hc, etc.) shown in the NMR lectures and problem sets. Justify your assignments by
use of the empirical (Curphy-Morrison) parameters found in the appendix of the
laboratory manual.
Use the 1H-NMR spectrum of the crude product mixture to determine the % conversion
of this reaction (assume there are no side reactions). Note that one of the signals of the
low abundance molecule is completely obscured. (10 pts)
2) Use the supplied spectral data to identify Compound 2, C14H12O2. (14 pts)
3) Use the supplied spectral data to identify Compound 3, C5H7BrO2. (14 pts)
4) Use the supplied spectral data to identify Compound 4, C11H14O2. (12 pts)
Questions 2 - 4 require you to use a combination of molecular formula, NMR and MS
data in order to identify each unknown compound; use all data supplied and hand in
all spectra for each question.
Clearly provide your calculation of the unsaturation number (IHD, DBE) value for each
compound.
Draw all molecules or fragments directly onto the provided spectra. Show all lone
pairs and charges for each structure. Write and sketch clearly!
Label each set of equivalent protons using the Ha, Hb, Hc etc. labeling system shown
in the 1H-NMR lectures and practice problem sets. Assign each 1H-NMR signal and
write your assignments directly onto the spectrum. Justify your assignments by use of
the empirical (Curphy-Morrison) parameters found in the laboratory manual.
Identify each 13C-NMR signal as either alkyl, vinyl, alkynyl, aryl, nitrile, imine, or
carbonyl (you do not need to assign individual carbon atoms to each signal).
Assign each key IR absorption band >1500 cm-1 to a specific functional group.
Draw fragments for all labeled peaks in the EI-MS directly onto the spectrum (you do
not need to show the fragmentation mechanism).
2
1) Aerobic Oxidation Crude Product Mixture 1H-NMR
3
2) Compound 2 (C14H12O2): 1H-NMR
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
8 7 6 5 4 3 2 1 -0
300 MHz ¹H NMRIn CDCl3
ALL RIGHTS RESERVED© 2014, Sigma-Aldrich Co.
2.00 2.10
3.19
2.15 1.08
2.14
4
2) Compound 2 (C14H12O2): 13C-NMR
165.259
148.665
135.403
133.397
130.066
129.920
129.645
128.464121.300
77.421
77.001
76.580
20.879
0.000
200 180 160 140 120 100 80 60 40 20 0
75 MHz ¹³C NMRIn CDCl3
ALL RIGHTS RESERVED© 2014, Sigma-Aldrich Co.
5
2) Compound 2 (C14H12O2): IR
6
2) Compound 2 (C14H12O2): EI-MS
212
105
77
7
3) Compound 3 (C5H7BrO2): 1H-NMR
8
3) Compound 3 (C5H7BrO2): 13C-NMR
9
3) Compound 3 (C5H7BrO2): IR
10
3) Compound 3 (C5H7BrO2): EI-MS
4)
178 180
147 149
119 121
99
11
4) Compound 4 (C11H14O2): 1H-NMR
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
8 7 6 5 4 3 2 1 0
300 MHz ¹H NMRIn CDCl3
ALL RIGHTS RESERVED© 2014, Sigma-Aldrich Co.
1.05
9.37
1.00 1.01
1.92
12
4) Compound 4 (C11H14O2): 13C-NMR
147.323
145.285145.042
117.774
107.568
106.323
100.679
77.42177.001
76.564 34.594
31.570
0.000
200 180 160 140 120 100 80 60 40 20 0
75 MHz ¹³C NMRIn CDCl3
ALL RIGHTS RESERVED© 2014, Sigma-Aldrich Co.
13
4) Compound 4 (C11H14O2): EI-MS
178
14
Last Name (print): ____________________________________ CHEM 344
Summer 2014
First Name (print): ____________________________________ Spectroscopy Problem Set
TA’s Name: __________________________________________
1) _______ (10 pts)
2) _______ (14 pts)
3) _______ (14 pts)
4) _______ (12 pts)
Total _______ (50 pts)
_______ (math double-check)