CH2710 - Organic Chemistry I (Katz)
Practice Exam #3- Fall 2013
Name:____________________________________________
Score:___________
Part I - Choose the best answer and write the letter of your choice in the space provided. (32 pts)
____ 1. Of the following, which reaction proceeds through syn addition ?
A) halogenation of an alkene with Br2 and CCl4
B) conversion of an alkene to a bromohydrin with Br2 and H2O
C) hydration of an alkene by oxymercuration
D) hydration of an alkene by hydroboration-oxidation
____ 2. Na dissolved in ammonia is used for converting:
A) alkyl halides to amines
B ) alkynes to trans alkenes
C) cis alkenes to trans alkenes
D) alkynes to cis alkenes
____ 3. The diagram at right represents
Base
H
A) The final step in an E1 reaction
B) The rate-limiting step in an E2 reaction
C) The rate limiting step in an SN1 reaction
D) The final step in an SN2 reaction
____ 4. As a class of hydrocarbons, terminal alkynes are distinctive among hydrocarbons because:
A) their terminal hydrogens are the most acidic hydrogens of all classes of hydrocarbons
B) they react with Br2 in CCl4 via a syn addition
C) they are the least thermodynamically stable of all classes of hydrocarbons
D) they do no react with BH3 in THF
____ 5. Which of the following sets of conditions would most likely produce an enantiomerically pure
product through complete inversion at a chiral center?
A) reaction of strong base with a secondary alkyl iodide in methanol
B) reaction of a weak base with a tertiary alkyl iodide in water
C) reaction of a strong nucleophile with a primary alkyl bromide in DMSO
D) reaction of a strong nucleophile with a secondary alcohol in water
H
O
O
____ 6.
and
A)
B)
C)
D)
represent
conformational isomers
diastereoisomers
constitutional isomers
tautomers
____ 7. Which are the “contaminants” which produce anti-Markovnikov products in
hydrohalogenations?
A) excess acids or bases
B) radicals
C) communists
D) liberals
______8. Of the following compounds,
F
E
Br
CH3
I
Z
H3C
H
Cl
H3C
CH2CH3
Z
I
the total number of E isomers represented is:
A) 4 B) 3 C) 2 D) 1
H
F
Br
CH2CH3
E
CH2OH
CH3
______9. The rate-determining step in the hydration of an alkene is:
A) addition of OH- to the carbocation
B) loss of a proton
C) rearrangement of the product to form the Markovnikov isomer.
D) carbocation formation
_____10. The incorrect IUPAC name among the following is:
A) 4-methylcyclobutene
B) 5-bromo-2-chloro-2-hexene
C) 3-ethyl-3-hexene
D) 3,4-dimethylcyclopentene
_____ 11.Which compound is the major organic product of the following reaction?
CH3
O
Br
?
A
B
C
D
_____ 12. Which set of reagents would give the given product for this reaction?
O
A)
B)
C)
D)
1.
1.
1.
1.
Hg(OAc)2 in THF/H2O followed by 2. NaBH4
BH3,
2. H2O2, -OH,
3. NaH, 4. CH3CH2CH2I
Hg(OAc)2 in THF /H2O followed by 2. CH3CH2CH2OH
BH3,
2. H2O2, -OH
_____ 13. Which compound is not a possible product from addition of Br2 to 1-butyne?
Br
H
Br
Br
Br
Br
H
Br
Br
Br
A
Br
Br
B
H
C
D
_____ 14.Addition of Br2 to cyclopentene would give a product which is
A) achiral
B) racemic
C) meso
D) optically active
Br2
_____ 15. Which of the following alkynes could be used to make this ketone selectively?
O
A
B
______ 16. The following reaction does not proceed to yield the indicated substitution product:
+
C
C
X
CH3
I
Which product is produced?
A
B
C
D
Part II-Provide IUPAC names for the following molecules. Don't forget to indicate stereochemistry
when applicable (i.e R or S, cis or trans). ( 12 pts )
17.
18.
Cl
H3C
H
Cl
(E)-2,3-dichloro-2-hexene
(S)-4,5-dimethyl-2-hexyne
19.
1,5,5-trimethylcyclopentene
Part III-Draw structures for the following molecules. ( 12 pts )
F
F
20.
(Z)-3-isopropyl-2-hexene
21.
3,6-difluoro-4-isopropyl-1-heptyne
Br
Br
22.
1,3-dibromo-4-ethylcyclohexene
Part IV - Draw a detailed mechanism for the following hydration reaction, providing the structures of
all relevant intermediates and indicating any movement of electrons, hydrogens, or methyl groups
with curved arrows ( 14 pts) .
H3O+
H2O +
23.
OH
H
O
H
H
O
H
H
O
O
H
O
H
H
H
H
Part V - The following alkene reacts with Br2 to give two stereoisomers. Complete the structures of the
two products and give them complete systematic names ( 12 pts ) .
H3C
H
Br2
24.
H3CH2C
CH(CH3)2
Br
H
Br
H3C
CH(CH3)2
CH2CH3
H3C
H
Br
CH2CH3
(3R,4R)-3,4-dibromo-2,4-dimethylhexane
CH(CH3)2
Br
(3S,4S)-3,4-dibromo-2,4-dimethylhexane
Part VI - Propose a synthetic scheme (a sequence of reactions) which will yield the given product from
the indicated starting material. You may utilize any common organic or inorganic reagents. (16 pts)
25.
Br2
CH3I
Br
2 eq
base
NaNH2
H
Br
26.
H
O
CH3
OH
H3C
H
H
O
CH3
OH
H3C
acid,heat
H
RCOOOH
HBr
1 eq
base
Br