LAST NAME :___________________________________
FIRST NAME :__________________________________
CHEMISTRY 331
EXAM II
Fall 2015
Dr. Winter and Dr. Zhao
1)
12
points
2)
15
points
3)
9
points
4)
5
points
5)
12
points
6)
47
points
100
points
Total
1) (12 points total, 3 points each) Indicate whether the pair of molecules are identical
compounds, enantiomers, diastereomers, or constitutional isomers.
(a)
OH
HO
Identical
Enantiomers
and
Diastereomers
(b)
Br
and
COOH
COOH
Br
Diastereomers
(c)
Cl
F
Identical
Cl
and
Br
Br
Identical
F
Br
Br
Diastereomers
Constitutional isomers
Enantiomers
Constitutional isomers
Enantiomers
Constitutional isomers
(d)
and
Identical
Diastereomers
Enantiomers
Constitutional isomers
2) (15 points total) Assign the correct R or S designation to the chirality centers indicated.
3) In the boxes, indicate how many signals you would see for each compound in the 13C NMR
spectrum: (9 points, Et = ethyl).
4) Circle all of the chiral molecules below: (5 pts)
5) Write in each space which technique below is best able to give the following information
about a molecule (12 pts). An answer may be used more than once.
NMR Spectroscopy, IR spectroscopy, Polarimetry, Mass Spectrometry
a. Whether a compound is chiral: ___________________________
b. What functional groups are present in a molecule: _______________________________
c. Determine the molecular weight of a molecule: ________________________________
d. Whether a compound is D (+) or L(-) : ________________________________
e. Could most easily distinguish 2-methylhexane from 3-methylhexane:
__________________________
f. How many chemically unique carbons are in a molecule:
__________________________
6) (47 points) Propose structure for each molecule consistent with the data given, and place it in the box
provided.
(a) (6 point)
C5H11Cl
1
 = 0.96 (triplet, 3H)
 = 1.53 (quartet, 2H)
 = 1.64 (singlet, 6H)
H NMR:


(b) (6 point)
C9H12
1
 = 1.21 (doublet, 6H)
 = 3.12 (septet, 1H)
 = 7.08-7.13 (multiplet, 5H)
H NMR:


(c) (7 point)
C5H10O
IR:
1725 cm-1 (strong)
1
 = 1.17 (singlet, 9H)
 = 9.52 (singlet, 1H)
H NMR:

13

C NMR:
C8H4O3
1
 = 7.81 (doublet, 2H)
 = 8.34 (doublet, 2H)

13
(b)
(c)
 = 24.5, 50.4, 206.3
(d) (7 point)
H NMR:
(a)

C NMR:
 = 129.7, 130.2, 133.9,
163.5
(d)
(e) (7 point)
C5H6O2
IR:
3320 cm-1
2230 cm-1
1715 cm-1 (strong)
1
 = 1.30 (triplet, 3H)
 = 2.70 (singlet, 1H)
 = 4.20 (quartet, 2H)
H NMR:

(e)

(f) (7 point)
C15H14O3
IR:
1690 cm-1 (strong)
1
 = 3.73 (singlet, 6H)
 = 6.87 (doublet, 4H)
 = 7.59 (doublet, 4H)
H NMR:

13

C NMR:
 = 55.9, 114.0, 131.3,
132.0, 164.4, 196.3
(g) (7 point) C8H18O
IR:
no peaks > 3000 cm-1
1
 = 1.2 (singlet, 18H)
H NMR:
(f)
Approx. IR absorptions
Class
Alkane
Alkene
Wavenumber (cm-1)
2850-1960
3020-3100
1640-1680
3300-3320
2100-2260
3400-3650
1050-1200
1070-1150
1670-1780
Group
C–H
C–H
C=C
C–H
C≡C
O–H
C–O
C–O
C=O
Alkyne
Alcohol
Ether
Aldehyde
Ketone
Approximate NMR absorptions
Partial
Structure
CH3
1
H NMR
 (ppm)
Partial
Structure

X CH
1
H NMR
 (ppm)

Partial
Structure
CH3
13
C NMR
 (ppm)

Partial
Structure
13
C NMR
 (ppm)
N C

F C

(X = Cl, Br, I)
CH2

CH

CH2
O CH
H
C C
CH
C C

Ar-H
Ar-CH3
C CH



C H
C O H
O
O H
Br
C

Cl
C

I
C



O
O
C CH3


C
CH3


C C

C C



(variable)
Aromatic
Carbons


O C

R
R
O
C
O
C
R

X

(X= OR' or NR'2)