1HNMR Problems Problems Problems

1
1H-NMR Problems! Problems! Problems!

• Chemistry 220
• Spring 2003

2
The 3 Steps in NMR Interpretation

• Number of unique resonances and their chemical
  shifts
• Compare to chemical formula
• Begin to build some fragments
• Integration proton count
• Add correct of protons to the fragments from
  Part 1
• Splitting patters
• Now, connect the fragments together
• Check for any unaccounted carbons or heteroatoms
• Complete the structure

3
What Are These Patterns?
4
Ethyl and Isopropyl, of course!
5
cis/trans Coupling
Jcis 4.7 Hz
Jtrans 13.0 Hz
Vinyl protons 5-7 ppm
6
Another Classical Resonance
9
3
2
7
C7H14O2
8
C7H14O2
a
b
e
d
c
9
Two Isomers With Molecular Formula C8H7Br

• Remember (pr)?? see p. 191 of text
• This is the number of p bonds and/or rings in a
  molecule

C8H7Br
No. of Hs in C7 alkane
10
Two isomers C8H7Br with (pr)5
11
Two isomers C8H7Br with (pr)5
12
C3H7Br
triplet
sextet
triplet
13
C3H7Br
a
c
b
c
a
b
14
C4H9Br
doublet
triplet
pentet
sextet
15
C4H9Br
a
b
c
d
a
b
d
c
16
Last Slide on NMR!!!

• Work Problems!
• Work Problems!
• Work Problems!