Download Ex 2 Spr 12-1 (1)

CHEM 2370
April 13th, 2012
Dr. S. A. Dandekar
Exam 2
(100 points)
Name:
Select the best answer from the given choices for ANY 20 of the following questions 1-24.
(5 points each)
You may answer extra questions to earn extra credit: 2 points for each extra correct
answer.
1. Select the potential energy diagram that represents a two-step endothermic (endergonic)
reaction.
A)
B)
C)
D)
E)
V
III
I
II
IV
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CHEM 2370
Dr. S. A. Dandekar
Exam 2
2. What is the major product for the following reaction?
Br2, H2O
A)
+ enantiomer
Br
OH
B)
+ enantiomer
HO
Br
C)
+ enantiomer
Br
OH
D)
+ enantiomer
HO
Br
E)
+ enantiomer
HO
OH
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April 13th, 2012
CHEM 2370
Dr. S. A. Dandekar
April 13th, 2012
Exam 2
3. The structure of the product, C, of the following sequence of reactions would be:
NaNH2
A
CH3CH2Br
B
NH3(l)
H2
C
Ni2B [P-2]
A)
B)
C)
Br
D)
E)
4. Consider the SN2 reaction of butyl bromide with OH- ion.
CH3CH2CH2CH2Br + OH-  CH3CH2CH2CH2OH + BrAssuming no other changes, what effect on the rate would result from simultaneously
doubling the concentrations of both butyl bromide and OH- ion?
A) It would double the rate.
B) It would increase the rate four times.
C) It would increase the rate six times.
D) It would triple the rate.
E) No effect.
5. You want to synthesize 3-methyl-2-pentene from 2-chloro-3-methylpentane. Which
reagent would you use?
A) CH3CH2OH, heat
B) CH3CH2ONa, CH3CH2OH, heat
C) HCl, heat
D) CH3CO2Na, CH3CO2H, heat
E) NH3(aq), 25oC
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CHEM 2370
Dr. S. A. Dandekar
April 13th, 2012
Exam 2
6. Heats of hydrogenation data would be useful in comparing the relative stabilities of
which of the following substances?
I
II
III
IV
V
A) I, II, V
B) Heats of hydrogenation data would not be a useful way to compare relative
stabilities of any of the substances.
C) III, IV
D) I, II, III
E) All of the above substances could effectively be compared using heats of
hydrogenation data.
7. A true statement about the transition state(s) of an SN2 reaction is:
A) existence of this transition state implies an exothermic reaction.
B) the two transition states are of unequal energy.
C) the transition states precede and follow an unstable reaction intermediate.
D) the transition state will always have a net charge of -1.
E) the single transition state represents the point of maximum free energy of the
reaction.
8. A solution of which of these allenes will rotate plane-polarized light?
H
H
C
C
H
H
C
H
C
H
C
Cl
I
H
C
C
H
H
C
C
Cl
C
Cl
C
Cl
V
I
IV
II
III
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C
Cl
V
IV
A)
B)
C)
D)
E)
C
C
Cl
III
Cl
Cl
C
Cl
II
Cl
H
CHEM 2370
Dr. S. A. Dandekar
Exam 2
April 13th, 2012
9. An unknown compound, A, has the molecular formula C7H12. On oxidation with hot
aqueous potassium permanganate, A yields CH3CH2COOH and (CH3)2CHCOOH.
Which of the following structures best represents A?
A)
B)
C)
D)
E)
10. What is the major product for the following reaction?
a. BH3:THF
b. H2O2, NaOH
A)
OH
+ enantiomer
B)
HO
+ enantiomer
C)
HO
D)
HO
+ enantiomer
E)
More than one of the above
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CHEM 2370
Dr. S. A. Dandekar
April 13th, 2012
Exam 2
11. Consider the reaction of 2-chloro-2-methylpentane with sodium iodide.
NaI
NaCl
Cl
I
Assuming no other changes, how would it affect the rate if one simultaneously doubled
the concentration of 2-chloro-2-methylpentane and sodium iodide?
A) It would increase the rate five times.
B) No effect
C) It would quadruple the rate.
D) It would double the rate.
E) It would triple the rate.
12. What would be the major product of the following reaction?
Br2, CCl4
C2H5
C2H5
Br
Br
CH3 H3C
Br
H
Br
Br
H
H
A)
B)
C)
D)
E)
C3H7
C2H5
C2H5
H3C
C3H7
?
Br
Br
H
CH3
Br
C3H7
C3H7
I
II
III
IV
Equal amounts of III and IV
I and II as major products, III and IV as minor products
Equal amounts of II and III
Equal amounts of I and II
All of the above in equal amounts
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CHEM 2370
Dr. S. A. Dandekar
April 13th, 2012
Exam 2
13. What will be the major product of the following reaction?
85% H3PO4
?
heat
OH
A)
B)
C)
O
D)
E)
14. What would you expect to be the chief organic product(s) when 2-bromo-2methylpentane react(s) with sodium propynide, i.e.,
Br
C:
I
II
HC
IV
A)
B)
C)
D)
E)
?
Na
III
CH
HC
CH
V
IV
V
I
II
III
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CHEM 2370
Dr. S. A. Dandekar
April 13th, 2012
Exam 2
15. Treating 1-methylcyclohexene with H3O+ would yield primarily which of these?
HO
HO
HO
I
II
III
HO
OH
IV
A)
B)
C)
D)
E)
V
I, III and V
I and V
II
III and V
IV
16. What is the major product for the following reaction?
a. Hg(OAc)2, H2O
b. NaBH4, NaOH
A)
+ enantiomer
B)
HO
OH
+ enantiomer
C)
OH
+ enantiomer
OH
D)
OH
+ enantiomer
E)
OH
+ enantiomer
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CHEM 2370
Dr. S. A. Dandekar
Exam 2
April 13th, 2012
17. An alkene adds hydrogen in the presence of a catalyst to give 3,4-dimethylhexane.
Ozonolysis of the alkene followed by treatment with zinc and acetic acid gives a single
organic product. The structure of the alkene is:
CH3
A)
CH3CH2C=CCH3
B)
(cis or trans)
CH2CH3
CH2
CH3CH2CCHCH2CH3
C)
CH3
CH3
CH3CH2CHCHCH=CH2
CH3
D)
CH3
CH2=CCH2CHCH2CH3
E)
CH3
CH3
CH3CH=C-CHCH2CH3
(cis or trans)
CH3
18. Which reaction would yield a meso compound?
i) OsO4
A)
cis-2-Butene
ii) NaHSO3
dil KMnO4
B)
trans-2-Butene
o
5C
H2/Pd
C)
cis-2-Butene
Br2/CCl4
D)
cis-2-Butene
E) None of these
19. Which is the strongest nucleophile?
A) CH3CH2OH
B)
C) H2O
D) CH3CH2OE) OH-
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CHEM 2370
Dr. S. A. Dandekar
April 13th, 2012
Exam 2
20. Which structure represents (Z)-1,4-dichlorohex-3-en-1-yne?
A)
Cl
Cl
B)
Cl
Cl
C)
Cl
Cl
Cl
D)
E)
Cl
None of the above
21. Addition of hydrogen chloride to the following molecule would produce:
HCl
?
Cl
Cl
Cl
Cl
Cl
Cl
Cl
A)
B)
C)
D)
E)
Cl
Cl
Cl
Cl
I
II
III
IV
V
I and II
II and III
I and IV
All of the above are equally likely to be formed
V
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CHEM 2370
Dr. S. A. Dandekar
April 13th, 2012
Exam 2
22. Which alcohol would initially produce the most stable carbocation when treated with
concentrated H2SO4?
A)
OH
B)
HO
C)
OH
D)
OH
E)
HO
23. What would be the major product(s) of the following reaction?
Br
EtOH
20 oC
EtO
OEt
I
A)
B)
C)
D)
E)
II
III
IV
I and II
II and III
I and III
None of the above
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CHEM 2370
Dr. S. A. Dandekar
Exam 2
April 13th, 2012
24. Consider the substitution reaction that takes place when (R)-3-iodo-3-methylheptane is
treated with sodium acetate (CH3CO2Na). Which of the following would be true?
A) An SN1 reaction would take place, accompanied by an E1 reaction, affording a
complex mixture of products.
B) An SN2 reaction would take place with inversion of configuration at the stereogenic
center.
C) An E2 reaction would take place, during which the stereogenic center is lost.
D) An SN1 reaction would take place with racemization of configuration at the
stereogenic center.
E) An SN1 reaction would take place with retention of configuration at the stereogenic
center.
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CHEM 2370
Dr. S. A. Dandekar
Exam 2
Answer Key
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
D
D
E
B
B
A
E
E
E
D
D
D
E
A
E
A
A
A
D
D
B
D
D
A
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April 13th, 2012