Sample Questions for First Exam Material
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1.
The molecule below undergoes a solvolysis reaction upon being refluxed in ethanol. Two products are
obtained.
Br
1.1.
Give both of the products for the reaction mentioned above
1.2.
Indicate the major product.
1.3.
A different precursor (with the same molecular formula, C7H11Br) gives identical products in
identical yields. Give the structure of this precursor.
Chem 324 Exam 1
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3.
Circle the best correct answer (only ONE) for each of the multiple-choice questions below.
3.1.
The experimental heat of hydrogenation for benzene is lower than the predicted heat of
hydrogenation for the hypothetical molecule, 1,3,5-cyclohexatriene. Which one of the following
conclusions can be drawn from the above finding?
(1)
(2)
(3)
Benzene is less stable than the hypothetical molecule, 1,3,5-cyclohexatriene.
Benzene is more stable than the hypothetical molecule, 1,3,5-cyclohexatriene.
Benzene cannot be hydrogenated in the presence of hydrogen gas and the appropriate
catalyst.
The heat of hydrogenation for benzene is likely to be lower than the heat of
hydrogenation for cyclohexene.
(4)
3.3.
Which of the following dienes reacts fastest in a Diels-Alder reaction with CH2=CHCO2CH3
CO2CH3
H3CO2C
(1)
3.4.
O
(2)
(3)
(4)
In a possible Diels-Alder reaction which two of the designated carbons below would form bonds
with a dienophile?
1
1
2
2
3
3
OH
(1) only 1
(2) only 2
(3) only 3
(4) either 1 or 3, since they are equivalent
(5) the compound above is an aromatic substance; therefore it does not undergo a Diels-Alder
reaction
3.6.
Which of the following compounds is likely to react with bromine in the absence of a Lewis acid?
O
CF3
(1)
NHCH3
CH3
(2)
(3)
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OCH3
(4)
Chem 324 Exam 1
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4.
Write the structure(s) of the major product(s) for each of the reactions below. If no reaction is expected
under the conditions specified, write “no reaction”.
HCl
(a)
?
THF (solvent)
H
N
CH3
HNO3
(b)
?
SO3H
H2SO4
HBr
(c)
?
THF (solvent)
(d)
O
O
Br2 (1 equivalent)
?
FeBr3
(9)
6.
Show a correct sequence of reactions for the multiple-step synthesis below. Indicate all reagents, reaction
conditions, and intermediate products
OCH3
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Chem 324 Exam 1
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7.
Two constitutional isomers of molecular formula C8H12O are formed in the following reaction. Ignoring
stereochemistry, suggest reasonable structures for these Diels-Alder adducts.
O
+
heat
solvent
7.1.
Identify the Diels-Alder precursors for the following product
O
?
+
?
heat
solvent
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8.
Show how m-bromobutylbenzene can be prepared selectively starting from benzene in a multi-step
synthesis. You can use any other precursors (organic or inorganic) as well as reagents of your choice.
Make sure to show clearly the correct sequence of reactions. Indicate all reagents, reaction
conditions, and intermediate products
Br
(9)
9.
The following reaction gives the expected product only in less than 20% yield; instead a disubstituted
major product with a rearranged side-chain is obtained.
Explain by showing details of mechanism (where appropriate)
(a) why the side-chain has undergone rearrangement
(b) why the product is disubstituted
CH3
+
Cl
AlCl3
CH2CCH2CH3
+
CH3
actual
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expected
Chem 324 Exam 1
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1.
When 1-bromo-3-methylcyclohex-2-ene is refluxed in ethanol, two products, which are regioisomers of
each other, are obtained. Identify the structure of the missing product A.
CH3CH2OH
Br
1.1.
+
heat
A
OCH2CH3
When the bromo compound B (which is different than the one above) undergoes the same reaction
as above, identical products (to those above), in identical yields are obtained. Identify the structure
of the precursor B.
B
CH3CH2OH
+
heat
A
OCH2CH3
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2.
Complete the following reactions by supplying the correct structures for the missing precursors and
products.
HH
O
2.1.
?
+
?
O
O
2.2.
H5C6
C6H5
+
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?
Chem 324 Exam 1
B. Terem
3.5.
Which of the following molecules is the most basic?
OH
OH
O2N
NO2
N
H
(1)
3.6.
N
NO2
(2)
(4)
(3)
Identify the least unstable (most stable) carbocation out of those given below.
(1)
(2)
(3)
(4)
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4.
Write the structure of the major product for each of the reactions below.
O
Cl2
(a)
?
FeCl3
O
OCH(CH3)2
SO3
H3C
(b)
?
H2SO4
HCl (1 eq)
(c)
?
H2O / THF
reflux - high Temperature
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8.
Write down structures for the missing products in the sequence of reactions below.
O
Cl
?
AlCl3
Zn (Hg)
?
HCl
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NBS (1 eq)
uv light
CH2Cl2
?
NaOCH2CH3
THF
Chem 324 Exam 1
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3.2. In which of the -intermediates below does the substituent stabilize the intermediate the least?
CH 3O
H3C
H
H
N
NO 2
NO 2
H
H
NO 2
NO 2
(2)
(1)
3.6.
Cl
H
(4)
(3)
Identify the weakest carbon-hydrogen bond in the following diene.
1)
H
3)
H
H
H
H3C
H3C
H CH
3
4)
2)
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7.
Write the structure of the major product for each of the reactions below.
(a)
H3CO
NO2
Br2
+
FeBr3
?
(1 equivalent)
(b)
(c)
+
HBr
?
H2SO4
?
+
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