Transcript NMR practice problems

Additional Office Hour Time
• Every Thursday, 2-3pm in Mol Sci 4100
(the person leading this office hours will be
different each week)
• BEGINS TOMORROW and will go to the
end of the quarter
NMR practice problems
Sources:
Web Spectra:
http://www.chem.ucla.edu/~webspectra/
Spectral Database of Organic Compounds (SDBS)
http://riodb01.ibase.aist.go.jp/sdbs/cgibin/cre_index.cgi
LEGEND:
-1H means an integration value of “1”, while 2H
means an intergration value of “2” etc.
- s = singlet
- d = doublet
- t = triplet
- m = multiplet
Ch14C, Spring 2012
Prof. Dong
Rough 1H-NMR guidelines
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Aldehyde
Aromatic
Vinylic
-OCH3
Ketone (α position)
H-C≡C-R
-CH3
TMS
Si(CH3)4
10 ppm
7-9
5-7
3-4
2
2
0-1
0 (we use this as reference)
For next several slides, the chemical structure and its 1H-NMR spectra is given
to you. Please try to assign as many of the protons to the peaks shown.
Confirm the following 4 features:
1. Number of equivalent protons
2. Chemical shift
3. Integration
4. Splitting
Also, using the molecular formula, calculate the DBE and confirm that it matches
the structure shown
Position of peak on 1H-NMR depends on the
“chemical” environment around the proton
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Each of the molecules below give 1 peak on 1H-NMR because all the protons experience the
same chemical environment
H
H2
C
H2C
CH2
H2C
C
H2
H
H
H
H
O
H
2
PPM
1
8
7 0
6
3
5
4
PPM
2
3
PPM
2
1
1
0
Beginner #7, C14H14
H
H
H
H H
H
H
H
H H
H
H
H
H
4H,s
10H,m
(overlap)
Beginner #10, C10H10O2
O
H
H
OCH3
H
H
3H, s
H
H
H
1H,m
1H,m
1H,m
1H,m 1H,m
1H,m
1H,m
Beginner #12 C6H12O2
O
H3C
O
H2
C
C
H2
H2
C
CH3
3H,s
2H, t
2H,pentet
3H,t
2H,sextet
Beginner #27, C3H7OCl
Cl
H2
C
C
H2
H2
C
OH
2H, t
1H, s
2H, t
2H, pentet
Beginner #25, C4H8O
O
H3C
C
H2
CH3
3H, s
3H, t
2H, q
Int1 #1, C3H4O
H
H
H
H
O
3H (overlapping peaks)
1H,d
Int2 #13, C10H15N
H3C
H2
C
N
H
H
H
6H,t
2H,m 3H,m
CH3
H
H
4H,q
H2
C
Int#12, C7H9NO
NH2
H
O
H
H
H
3H,s
4H,m
2H,s
CH3