Sample Exam 1 Answer Key. I. Write structures ... Another name for 1,3
dibromobenzene is meta-dibromobenzene. 3. Benzene is .... CH2=CH-CH 3 +
Br2. OH.
Organic Chemistry II CMH 2211 Sample Exam 1 Answer Key I.
Write structures for the compounds shown below: HO
OH
O NH2
Br
____________________ meta-bromophenol
__________________ o-aminobenzoic acid
__________________ phenanthrene
CH2 OH
____________________ 3-methyl-2-phenylhexane II.
__________________ benzyl alcohol
__________________ para-xylene
Name the compounds whose structures are shown below: CH3
Br Br
Br
2-bromotoluene ____________________
1,2-dibromocyclohexane __________________
cyclopentylbenzene __________________
O C
CH3
H
C H3C
Br
4-methylbenzaldehyde ____________________
anthracene __________________
H
(R)-1-bromo-1-phenylethane __________________
III. Fill in the Blank 1. In order for a compound to be aromatic it must satisfy certain rules. The compound or ion must be cyclic and planar, have all atoms in the ring with sp2 hybridization, and have a Huckle number of electrons in unhybridized p orbitals. 2.
Another name for 1,3 dibromobenzene is meta-dibromobenzene.
3.
Benzene is more stable than you might expect based upon a 6 membered ring and three double bonds. This is because benzene has resonance stabilization.
4.
Is 26 a Huckle number? (Y/N) Yes (4*6+2)
5.
Benzene ring deactivators have something in common. They all have the atom attached to the ring has a full or partial positive charge.
6.
Proton NMR of aromatic compounds show characteristic absorptions in the range of 7 to 8 ppm.
7.
Name two ring substituants that will prevent the ring from reacting in a FreidelCraft reaction. –NH2 and any strong deactivator.
8.
4-Methylbenzioc acid would tend to add a third group at carbon number 3.
V.
Answer the questions below by YES or NO.
a. b. c. d. e.
Is cyclopentadienyl anion aromatic? Is cyclopentadienyl carbocation aromatic? Is cyclopentadiene aromatic? Is cycloheptatriene aromatic? Does cycloheptatriene have a Huckle # of electrons?
V.
Answer the following:
__YES___ __NO____ __NO____ __NO____ __YES___
Consider the reaction of anisole (methoxybenzene) with SO3 in the presence of H2SO4 a.
Write the formula for the MAJOR product(s) of this reaction. OCH3
OCH3 SO 3H
b. c. d.
SO3H What is the electrophile in this reaction? SO3 ( HSO3+ ) How can it be an electrophile if it has no full positive charge? Positive formal charge on S Write a series of equations to show the mechanism of the above reaction. First show the mechanism when electrophilic attack is from the para position, and then show it from the meta position. Show all possible resonance forms of the arenium ion for both para and meta attack. Include the final step of conversion of the arenium ion to the product in your mechanism. USE KEKULE STRUCTURES.
See pages 693, 729, and 730 of your text. Page 693 shows general mechanism of EAS. Page 729 shows EAS with a substituant that has an unshared electron pair, and Page 730 shows the resonance forms for anisole with o, m, and p attack.
VI. Write structural formulas for the the products if a reaction occurs. If no reaction occurs write N.R. a.
CH3CH2Br AlBr3 NO 2
HNO3
b.
H2SO 4 NH2
NH2
c.
Br
Br2
Br
Br
NH2
d.
CHCl3
No Reaction
AlCl3
e.
Isobutyl bromide AlBr3 Br
f.
NH2
NH2 NH3 H3C
g.
NO 2
OCH3
O2N
Br2
OCH3 O2N +
FeBr3
Br
Cl O
h.
CH3 C O AlCl3
CH2CH3
i.
Br
NBS No Reaction Without Light or Other FR Conditions
NO 2
j.
CH3Cl AlCl3
No Reaction
COOH
KMnO4
k.
OH, heat CH2CH3
Br2 FeBr3 Br
CH=CH2
l.
Br
Br2
Br
Br
OCH3
m.
CH3
HF
+
CH3 C CH2 O
O
n.
o.
O
OH
AlCl3
light
H2O
Br2
CH2OH
No Reaction
HBr
OH
major
H2SO 4
Cl2
q.
r.
C
CH3Cl
p.
O2N
HNO3
No Reaction
O
Na
+ Na
OH
s.
HCl(aq)
+ H2
No Reaction
Br
t.
CH 2=CH-CH 3 + Br 2
u.
CH 3CH=CHCH 3 + MnO 4
Br
OH
O 2 CH3 C O
hot OH
v.
w.
x.
y.
OH
OH
+ MnO4
cold
CH4 + Br2 (limit)
No Reaction without F.R. conditions
CHO
CHO
+
t-butyl + CH3
CH3 Br CH3
t-butyl
AlCl3 t-butyl
O
C
VII. Multiple Choice a.
1.
Which of these gives mostly the meta product when treated with Br2 / Fe? O
a.
b.
Cl
c.
NH2
d.
d.
e.
2.
O-CH 3
Which undergoes electrophilic substitution on the ring most rapidly? Cl
a.
b.
OH
d.
b.
3.
c.
SO 3H
CHO
e.
In the reaction of 2-nitrotoluene with bromine in the presence of iron , which of the products shown below is the most abundant in the mixture? O
a.
CH3
N
Br
b.
CH3
O
CH3
c.
N O
O
O N Br
CH3
d.
Br
e.
CH3
O
O N
O
O
N O
b.
e.
Br
Br
4.
Which is characteristic for the proton NMR pattern of diethyl ether?
a. b. c. d. e.
An upfield singlet and a downfield doublet. An upfield triplet and a downfield quartet. An upfield singlet and a downfield triplet. Two upfield triplets on top of each other. One downfield singlet.
5.
Which of the following would be the most likely to undergo a nucleophilic aromatic substitution with hydroxide ion in normal conditions?
