351 Organic Chemistry II
Exam #2B, 3/4/2011
Winona State University
Professor T. Nalli
Name_____________________________
General Instructions: Write your name in the space provided above and on the provided Scantron form. Do not put your name anywhere else in this exam book.
Make sure that you read each question carefully and provide complete answers. Time limit is 55
min. Exams must be turned in immediately upon my call of time up.
Grading: Grading will be on the basis of a highest possible score of 100 points.
I. Multiple Choice – 1.5 points each, 42 points total
II. Nomenclature/Structure – 1 point each, 6 points total
III. Synthesis – 10 pts
IV. Reaction Products – 6 points each, 42 points total
V. Assessment Day Survey – 5 pts extra credit
1
1.
Which of the following statements about benzene is incorrect?
A. All twelve atoms lie in the same plane.
B. The C-C bonds alternate in length between long and short.
C. All of the carbon atoms are sp2 hybridized.
D. The molecule is a hybrid of two resonance forms.
2.
Which scientist generally receives the most credit for coming up with the accepted structure of benzene?
A. Ladenburg B. Lohschmidt
C. Einstein
D. Lindberg
E. Kekule
For questions 3-8 decide which of these best describes the given structure:
A. Aromatic
B. Antiaromatic
C. Nonaromatic because it does not have an unbroken loop of p orbitals
D. Nonaromatic because the number of pi electrons does not obey the Huckel rule
E. Nonaromatic because there would be too much strain to allow the molecule to be planar.
N
O
3.
4.
N
5.
6.
7.
8.
9.
Which of the following provides evidence that the electrophile in FriedelA. Nitrobenzene cannot be alkylated with CH3CH2Cl/AlCl3.
B. Toluene reacts faster than benzene under the same conditions.
C. Ethylbenzene yields two products when reacted with CH3CH2Cl/AlCl3.
D. Benzene reacts with CH3CH2CH2Br/AlCl3 to give Ph-CH(CH3)2.
10.
Which of these substituents is a deactivating o,p-director?
A. methyl
B. chloro
C. hydroxyl
D. isopropoxy
11.
Crafts alkylation is a carbocation?
E. butyl
Which of the following reacts with HNO3 (H2SO4 catalyst) at the fastest rate?
O
NH CCH3
A.
12.
CH3
OCH3
B.
NO2
D.
C.
Which of the following reacts with HNO3 (H2SO4 catalyst) at the slowest rate?
O
OH
A.
B.
C
OH
SO3H
C.
CN
D.
13.
What is the effect of a methoxy (CH3O) substituent in electrophilic aromatic substitution reaction?
A. A methoxy group speeds ortho and para attack and slows meta attack.
B. A methoxy group speeds all modes of attack but speeds ortho and para attack the most.
C. A methoxy group slows all modes of attack but slows ortho and para attack the least.
D. A methoxy group slows all modes of attack but slows ortho and para attack the most.
14.
Which isomer of dinitrochlorobenzene reacts the fastest with NaOH to form a phenol?
A. 3,4-dinitro
B. 2,3-dinitro
C. 2,4-dinitro
D. 2,5-dinitro
15.
Which one of these reacts the fastest with sodium hydroxide to form a phenol?
A. m-fluoronitrobenzene B. p-fluoronitrobenzene C. m-bromonitrobenzene D.p-bromonitrobenzene
16.
Which term does not correctly describe Diels-Alder reactions?
A. pericyclic
B. stereospecific
C. heterolytic
2
D. cycloaddition
17.
Which of the following pairs of terms correctly characterize Diels-Alder reactions.
A. exothermic, concerted mechanism
B. endothermic, concerted mechanism
C. exothermic, stepwise mechanism
D. endothermic, stepwise mechanism
18.
What is the order of reactivity of compounds I - III as dienes in Diels-Alder reactions? (from most reactive to
least reactive)
I. trans-1,3-pentadiene II. cis-1,3-pentadiene III. 1,4-pentadiene
A. I > II > III
B. II > I > III
C. III > I > II
D. III > II > I
19.
Which of the following is expected to be the most reactive as a dieneophile in a Diels-Alder reaction?
A. CH2=CH-CH3
B. CH2=CH-OCH3
C. CH2=CH-Ph
D. CH2=CH-CN
20.
Which of the following dienes is suitable as the diene component in a Diels–Alder reaction?
21.
Which diene would be most reactive toward Diels-Alder reaction with maleic anhydride?
A.
B.
CN
C.
D.
CN
OCH 3
OCH 3
22.
Which of the following is not necessarily a characteristic of aromatic compounds?
A. An NMR spectrum that shows attached hydrogens are greatly deshielded.
B. A tendency to undergo substitution rather than addition reactions.
C. Possess strong aromas.
D. The atoms making up the aromatic ring lie in one plane
23.
Which shows the curved arrows correctly for attack of the electrophile in the sulfonation of benzene?
O
A.
+
O
O
S
B.
O H
+
S
H O
O
+
C.
O
O
S
O H
D.
O
S
+
H O
O
24.
How many total chlorofluorobenzene (C6H4ClF) isomers can exist?
A. two
B. three
C. four
D. five
25.
Which of the following electrophilic aromatic substitution reactions is reversible?
A. nitration
B. sulfonation C. halogenation D. alkylation
26.
How many total tribromobenzene isomers can exist?
A. one
B. Two
C. three
D. four
27.
Nitrobenzene exists as a resonance hybrid of how many main resonance structures?
A. two
B. three
C. four
D. seven
28.
Which choice is an intermediate in the reaction of NaNH2/NH3 with bromobenzene to form aniline (PhNH2)?
Br NH2
Br NH2
Br H
A.
B.
C.
D.
NH 2
3
II. (a) Give the structure of the following compounds.
1. 4-isopropylanisole
2. m-bromotoluene
3. o-chlorobenzoic acid
II. (b) Name each of the following structures.
NO 2
OH
V. Show a sequence of reactions by which each of the following compounds could be synthesized from benzene (5
points each).
Br
O
OH
I
4
III. Give the structure(s) of the main organic product(s) of each of the following reactions.
O
N 2H 4
1.
KOH
O
HNO 3
2.
H 2SO4
NBS, ROOR
3.
h, 
O
Br 2, FeBr3
4.
O
5.
+
AlCl3
Cl
O

6.
+
H 3CO2 C
CO2 CH3
O
+
O

7.
O
5