Sample Exam 3
(Chapters 9-12)
PART I- Multiple Choice
1. Consider the following structures, identify the type of isomers.
H
H3C
CH3
Br
H
Br
H
CH3
and
H
H3C
Br
A. identical
Br
B. Constitutional isomers
C. diastereoisomers
D. enantiomers
2. What is the correct absolute configuration for the following compouds?
H
A. R
B. S
C. achiral
D. cannot be determined
3. The (+) enanthiomer of a compound has an observed optical rotation of 1.75 degrees when
measured in a one dm tube at a concentration of 0.3 g/ 15 ml. What is the specific rotation ,
[], of the molecule?
A. 30 o
B. 45 o
C. 87.5o
D. 1.75 o
4. What is the correct configuration for the following compound ?
CH3
Br
H
H
OH
CH3
A. (2R,3S)
B. (2S,3S)
C. (2R,3R)
D. (2S,3R)
5. Which of the following is Simmons-Smith reagent?
A. R-Mg-X
B. (R)2CuLi
C. CH2I2/Zn(Cu)
D. none of the above
1
6. Identify the correct order of the following reaction mechanisms as SN1, SN2, E1, or E2
I. CH3CH2Br + H2O  CH3CH2OH + HBr
II. Rate = k[RX] for this elimination reaction
III. Using Nu– = Cl – or I – does not affect the rate of this substitution reaction
IV.
CH2Br
+ KOH
CH2
+ KBr + H2O
V. Results in inversion of configuration
A. SN2, E2, SN2, E1, SN1
C. SN1, E2, SN1, E1, SN2
B. SN2, E1, SN1, E2, SN2
D. SN1, E1, SN2, E2, SN1
7. The transformation is ____________________.
CH3
CH3
CH3 - CH - CH3
CH3 - C - CH3
Br
A. an oxidation
C. neither an oxidation nor reduction
B. a reduction
D. cannot be determined
8. In a mass spectrum of organic compound, mass-to-charge ratio (m/z) gives the information about
A. chiral centers
B. molar mass
C. functional groups
D. Isomerism
9. When a high energy electron strikes an organic molecule in Mass spectrometer, it dislodges a valence
electron from the molecule and produce___________
A. a cation
B. An anion
C. a cation-radical
D. a free radical
10. What is the main information you get from an IR spectrum of a compound?
A. atomic mass
B. number of C-H bonds
C. functional groups
D. bond lengths
11. IR spectrum is the result of
A.
B.
C.
D.
bombardment of high energy electrons with organic compound
interaction of electric component of electromagnetic radiation with organic molecule
interaction of magnetic component of electromagnetic radiation with organic molecule
interaction of visible light with organic molecule
12. Which one of the following is a tertiary alkyl halide?
A. 1-chloro-2-methylpentane
C. 2-chloro-3-methylpentane
B. 2-chloro-2-methylpentane
D. 1-chloropentane
2
13. Alkyl halides undergo elimination of HX, dehydrohalogenation, on treatment with a _______ .
A. strong base
B. weak base
C. strong acid
D. weak acid
14. A compound that possesses an internal plane of symmetry (where one half of the molecule is the
mirror image of the other half of the molecule) is __________.
A. enantiomeric
B. achiral
C. optically active
D. chiral
15. The organometallic reagent R – Mg – X is called a
A. Gilman reagent
B. Simons-Smith reagent
C. Grignard reagent
D. Ficher reagent
16. What is the final product of the following reaction?
CH3 - CH2 - CH2 Br
1) Mg/ether
2) H2O
A. CH3 – CH2 – CH2OH
B. CH3 – CH2 – CH3
C. CH3 – CH2 – CH2 Mg Br
D. CH3 – CH = CH2
PART II- Show your work
17. Name and assign R or S configurations
Br
H
Br
H3C
H
CH3
CH2CH3
_______________________________
(S)-2-hydroxybutane
CH3
H
Br
__________________________________
(2R,3S)-2,3-dihydroxybutane
3
18. Draw the structures of major products in the following reactions
a)
HBr /ether
CH3
CH2-CH2OH
PBr3
b)
OH
SOCl2
c)
pyridine
CH3
Mg /ether
d) CH3 - C = CH - CH3
H2O
Br
e)
CH3 - CH2 - CH - CH2Br
1) 2 Li, pentane
2) CuI
3) CH3-CHBr
CH3
CH3
f)
Br
KOH
19. Show by a series of reactions how could you prepare the following compounds from the
indicated starting compound. Be sure to clearly indicate the reagents used in each step.
( a) CH3 - C
C-H
CH3 - C
4
C - CH2
CH - CH3
( b)
CH3
c. Draw one enantiomer, and one diastereomer of the following compound.
OH
H
Br
CH3
H
CH2CH3
BONUS Question(10 points)- Show all your work.
Given The MS spectrum for a compound with only one oxygen, CxHyO , answer the
following questions.
a) Determine the position of parent peak and base peak.
b) Determine the possible structure of the compound.
c) What fragment has the highest intensity?
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SAMPLE ORGANIC CHEM 2423 EXAM # 3 Key (Chapters 9-12)
PART I- Multiple Choice
1-D, 2-A, 3-C, 4-B, 5-C. 6-B, 7-A, 8-B, 9-C, 10-C, 11-B, 12-B, 13-A, 14-B, 15-C, 16-B
PART II- Show youe work )
17.
(R) – 2- bromobutane
(2S,3S)2,3-dibromobutane
CH3
HO
H3C
HO
C2H5
H
H
OH
H
CH3
CH3
18.
a)
Br
CH2 - CH2Br
c)
Cl
b)
CH3
d)
CH3 - CH = CH -CH3
e) CH3 - CH2 - CH - CH2 - CH - CH3
CH3
CH3
f)
6
19.
( a) CH3 - C
C -CH2
CH3 - C
C-H
NaNH2
CH3 - C
CH2Br
C: Na
CH - CH3
(b)
CH3
Cl2
light
CH3CH- Br
2 Li
Cl
CuI
CH3
pentane
c.
OH
H
CH3
Diastereomer
OH
OH
CH3
H
H
Br
H
Br
Enantiomer
CH2CH3
CH3
H
Br
H
CH2CH3
CH2CH3
Bonus Question (10 points) – Show all your work.
parent peak , m/e = 84
base peak , m/e = 69
C5H8O , (two double bond) or one triple bond
Structure:
O
CH3 - C - CH2 - CH = CH2
m/z =84
O
CH- CH2 - CH = CH2
O
m/z = 69
C - CH3
7
m/z =43