ORGANIC CHEMISTRY 8Th Edition International Edition by John E. McMurry – Test Bank
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Sample Test
Chapter 3—Organic Compounds: Alkanes and Their Stereochemistry
SHORT ANSWER
Exhibit 3-1
MATCH a structure below to each of the following descriptions
and place the letter corresponding to the structure in the blank.
1. _____
is an amino aldehyde.
ANS:
B
2. _____
is an aromatic ketone.
ANS:
E
3. _____
is a tertiary chloride.
ANS:
C
4. _____
is a cyclic alkane with two cis methyl groups.
ANS:
C
5. Circle
and name each functional group in the following structure.
ANS:
Exhibit 3-2
Label the indicated atoms in the structure below as 1°, 2°, 3°,
or 4°.
6. Refer
to Exhibit 3-2. The atom at A is
_____.
ANS:
4°
7. Refer
to Exhibit 3-2. The atom at B is
_____.
ANS:
2°
8. Refer
to Exhibit 3-2. The atom at C is
_____.
ANS:
3°
9. Refer
to Exhibit 3-2. The atom at D is
_____.
ANS:
1°
Exhibit 3-3
Label the following pairs of compounds as:
|
a. |
identical |
|
b. |
constitutional isomers |
|
c. |
neither |
Place the letter of the correct answer in the blank.
10.
_____
ANS:
b
11.
_____
ANS:
c
12.
_____
ANS:
a
IUPAC Naming Instructions: Provide proper IUPAC
names.
13.
Name:
(CH3)2CHCH2CH2CH(CH2CH3)CH2C(CH3)3
ANS:
4-ethyl-2,2,7-trimethyloctane
14.
Name:
ANS:
7-bromo-3-ethyl-2,2,5,5-tetramethyloctane or 2-bromo-6-tert-butyl-4,4-dimethyloctane
15.
Name:
ANS:
5-isopropyl-3-methyloctane
16.
Name:
ANS:
5-ethyl-3,4-dimethyloctane
Drawing Instructions: Draw skeletal structures
corresponding to each of the given names.
17.
Draw: 6-ethyl-4-isopropyldecane
ANS:
18.
Draw: 2-fluoro-3-methylpentane
ANS:
19.
Draw: 4-(2,2-dibromoethyl)-3,5-dichloroheptane
ANS:
Exhibit 3-4
Experiments have shown that for 1,2-dichloroethane, ClCH2CH2Cl,
in carbon tetrachloride solution at 25 °C, 70% of the molecules are in
the anti and
30% are in the gauche conformation.
20.
Refer to Exhibit 3-4. Draw a Newman projection of the anti conformation
of 1,2-dichloroethane.
ANS:
21.
Refer to Exhibit 3-4. Draw a Newman projection of the gauche conformation
of 1,2-dichloroethane. Explain why the majority of the molecules are not in
the gauche conformation.
ANS:
The gauche conformation
is a higher energy state than the anti conformation
due to the torsional strain caused by the close proximity of the two chlorine
atoms.
Exhibit 3-5
CiproÒ (Ciprofloxacin) is a synthetic broad spectrum
antibacterial agent. It was most recently in the news as the antibiotic of
choice for the treatment of anthrax. The structure of CiproÒ is shown below.
22.
Refer to Exhibit 3-5. Circle the
functional groups in the CiproÒ representation above.
ANS:
Exhibit 3-6
Predict the hybridization of the indicated atoms in CiproÒ.
23.
Refer to Exhibit 3-6. The hybridization of this nitrogen atom (A) is __________.
ANS:
sp3
24.
Refer to Exhibit 3-6. The hybridization of this carbon atom (B) is __________.
ANS:
sp2
25.
Refer to Exhibit 3-6. The hybridization of this carbon atom (C) is __________.
ANS:
sp3
26.
Put a box around
the most polar bond
in CiproÒ based on electronegativity values.
ANS:
27.
Name the following hydrocarbon.
ANS:
2,3-dimethylbutane
Sight along the C2-C3 bond of 2-methylbutane.
28.
How many eclipsed conformations can be drawn?
ANS:
3
29.
Draw the staggered conformations.
ANS:
30.
Arrange the following conformation from lowest to highest
energy.
ANS:
31.
Explain your energy order from lowest to highest.
ANS:
The lowest energy conformation of those shown is the one
staggered conformation. Of the two eclipsed conformations
given, the one in which there is one eclipsed interaction (energy
cost: 11 kJ/mol) and one eclipsed interaction (energy cost: 6.0
kJ/mol) and one eclipsed interaction(energy cost: 4 kJ/mol,
for a total energy cost of 11 kJ/mol + 6 kJ/mol + 4 kJ/mol = 21 kJ/mol) will be
higher than the one in which there are three eclipsed interactions
(energy cost: 6.0 kJ/mol x 3 = 18 kJ/mol).
32.
Draw at least four isomers with molecular formula given below.
C4H10O
ANS:
There are seven total isomers, four alcohols and three ethers.
MULTIPLE CHOICE
1. Which
of the following functional groups if bonded to a three-carbon chain would have
the largest d– charge?
|
a. |
alcohol |
c. |
phosphate |
|
b. |
ether |
d. |
sulfide |
ANS: C
2. Which
of the following functional groups contains a carbonyl group?
|
a. |
ketone |
|
b. |
ester |
|
c. |
carboxylic acid |
|
d. |
amide |
|
e. |
All contain a carbonyl group. |
ANS: E
3. How
many isomeric chloroalkanes have the molecular formula shown below?
C4H9Cl
|
a. |
2 |
c. |
4 |
|
b. |
3 |
d. |
5 |
ANS: C
4. If
the following alkyl group were attached to a cyclohexane ring,
the group would be named as:
|
a. |
butyl |
c. |
sec-butyl |
|
b. |
isobutyl |
d. |
tert-butyl |
ANS: D
5. Which
of the following alkanes would have the highest boiling point?
|
a. |
heptane |
|
b. |
2-methylhexane |
|
c. |
2,3,-dimethylpentane |
|
d. |
2,2,3-trimethylbutane |
|
e. |
All have the same molar mass and would
have about the same boiling point. |
ANS: A
Chapter 5—Stereochemistry At Tetrahedral Centers
SHORT ANSWER
Exhibit 5-1
For the following question(s) MATCH each definition to a term
from the list below. Place the letter of the term in the blank to the left of
the definition.
|
a. |
racemates |
f. |
meso compounds |
|
b. |
chirality center |
g. |
optically active |
|
c. |
chirality |
h. |
prochirality center |
|
d. |
diastereomers |
i. |
optically inactive |
|
e. |
enantiomers |
j. |
achiral |
1. ____
describes organic molecules which rotate plane-polarized light.
ANS:
g
2. _____
is the property of “handedness”; the property of an object that causes it to be
nonsuperimposable on its mirror image.
ANS:
c
3. _____
are stereoisomers that are not mirror images.
ANS:
d
4. _____
is an atom in a molecule that is bonded to four different atoms or groups of
atoms.
ANS:
b
5. _____
are molecules which contain chirality centers and a plane of symmetry.
ANS:
f
6. _____
describes an sp3-hybridized
atom that can become a chirality center by changing one of its attached groups.
ANS:
h
7. The
specific rotation of a compound is denoted by the symbol:
|
a. |
R |
|
b. |
S |
|
c. |
a |
|
d. |
ANS:
d
Exhibit 5-2
Place asterisks at all the chirality centers in each molecule
below.
8.
ANS:
9.
ANS:
10.
ANS:
11.
ANS:
12.
ANS:
13.
ANS:
Exhibit 5-3
Assign R, S configurations to
each indicated chirality center in the molecules below.
14.
Refer to Exhibit 5-3. The configuration of this carbon atom (A) is _____.
ANS:
R
15.
Refer to Exhibit 5-3. The configuration of this carbon atom (B) is _____.
ANS:
S
16.
Refer to Exhibit 5-3. The configuration of this carbon atom (C) is _____.
ANS:
R
17.
Refer to Exhibit 5-3. The configuration of this carbon atom (D) is _____.
ANS:
S
18.
Refer to Exhibit 5-3. The configuration of this carbon atom (E) is _____.
ANS:
S
Exhibit 5-4
Consider the structure of streptimidone to answer the following
question(s).
19.
Refer to Exhibit 5-4. Assign R or S configuration to each chirality
center indicated in streptimidone.
ANS:
20.
Refer to Exhibit 5-4. Based on the number of chirality centers,
how many stereoisomers of streptimidone are possible?
ANS:
Streptimidone has two chirality centers so there are 22, or
4, possible stereoisomers.
21.
Refer to Exhibit 5-4. Will streptimidone have a meso stereoisomer?
Explain your answer.
ANS:
No. Meso compounds
are compounds that contain chirality centers, but possess a plane of symmetry.
Because the substituents on the chiral carbons are different in streptimidone
it is impossible for any stereoisomer to have a plane of symmetry.
Exhibit 5-5
Label each pair of stereoisomers below as:
|
a. |
enantiomers |
|
b. |
diastereomers |
|
c. |
identical |
Place the letter of the correct answer in the blank to the left
of the pair of stereoisomers.
22.
_____
ANS:
a
23.
_____
ANS:
c
24.
_____
ANS:
b
25.
_____
ANS:
b
26.
_____
ANS:
c
27.
_____
ANS:
a
28.
_____
ANS:
b
29.
Draw a wedge-dash projection of (2R,3S)-dibromobutane.
ANS:
30.
Draw a Newman projection of the most stable conformation of (2R,3S)-dibromobutane
sighting down the C2-C3 bond.
ANS:
31.
(2R,3S)-Dibromobutane
is:
|
a. |
optically active. |
|
b. |
racemic. |
|
c. |
dextrorotatory. |
|
d. |
a meso compound. |
ANS:
d
32.
Estriol, a potent estrogenic hormone, has been isolated from the
urine of pregnant women. When 40 mg of estriol is dissolved in 1.0 mL of
dioxane and placed in a sample tube with 1 dm path length a rotation of +2.32°
is observed. Calculate the specific rotation for estriol.
ANS:
Exhibit 5-6
Refer to the structure below to answer the following
question(s).
33.
Refer to Exhibit 5-6. (S)-(-)-Serine:
|
a. |
is dextrorotatory |
|
b. |
rotates plane-polarized light in a
counterclockwise direction |
|
c. |
rotates plane-polarized light in a
clockwise direction |
|
d. |
is racemic |
ANS:
b
34.
Refer to Exhibit 5-6. Draw the enantiomer of (S)-(-)-serine in a
wedge-dash projection.
ANS:
35.
Refer to Exhibit 5-6. Give the complete name of the enantiomer
of (S)-(-)-serine.
ANS:
(R)-(+)-serine
Exhibit 5-7
A natural product having [a]D =
+40.3° has been isolated and purified.
36.
Refer to Exhibit 5-7. This information indicates that the
natural product:
|
a. |
is racemic. |
|
b. |
does not rotate plane-polarized light. |
|
c. |
is levorotatory. |
|
d. |
is dextrorotatory. |
ANS:
d
37.
Refer to Exhibit 5-7. Two structures have been proposed for this
natural product. Circle the
structure that is consistent with the information presented and briefly explain
your choice.
ANS:
The information presented indicates that the natural product is
optically active. To be optically active molecules must be chiral¾that is, they
must not have
a plane of symmetry. The cyclic structure, although is has chirality centers,
has a plane of symmetry, indicated by the dashed line on the structure, and
can, therefore, not be optically active. The circled structure has four
chirality centers, and is not symmetric. We would expect it to be optically
active.
Exhibit 5-8
Identify the indicated hydrogens in the following molecules
as pro-R or pro-S.
38.
ANS:
39.
ANS:
Exhibit 5-9
Identify the indicated faces in the following molecules as re or si.
40.
ANS:
41.
ANS:
42.
Acetoacetate synthase catalyzes the addition of pyruvate to
b-ketobutyrate to yield a-aceto-a-hydroxybutyrate. If the addition occurs from
the si face
of b-ketobutyrate, what is the stereochemistry of the product?
ANS:
Addition of the aceto group to the si face results in
the S enantiomer
of a-aceto-a-hydroxybutyrate.
43.
Explain why a work glove is chiral but disposable surgical
gloves are not.
ANS:
Surgical gloves are not made to wear on a left hand or right
hand but can be worn on either hand with an equally good fit. This type
of glove is symmetrical with respect to the positioning of the covering that
goes on the thumb – it has a plane of symmetry.
OR
Work gloves have “front” and “back” sides. The thumb is
positioned differently with respect to the digits. Surgical gloves have
five symmetrical digits. They do not have “front” and “back” sides.
44.
A white solid known to be enatiomerically pure is dissolved in
water. This solution produced an observed optical rotation of
+45.6°. The solution was allowed to stand and the optical rotation
was measured repeatedly producing the data shown in the table.
|
Time (min) |
Observed Rotation (°) |
|
10 |
+39.9 |
|
20 |
+5.6 |
|
30 |
-1.2 |
|
40 |
-23.4 |
|
40 |
-23.4 |
Explain the pattern of observed rotation.
ANS:
Some type of reaction, possibly a hydrolysis, is occurring
and the optically active dextrorotatory compound is being converted to the
levorotatory enantiomer.
The change may be due to the production of a new compound with a
specific rotation of -23.4°. This
might be verified by using this value to identify the compound if enough other
informtion is know.
Assuming an equilibrium is established, an alternate explanation
could be that it appears from the final value of the observed rotation that an
equilibrium mixture of the two forms and that the levorotatory from
predominates in the mixture.
45.
Lactic acid exists in two enantiomeric forms. In muscle tissue
only (+)-lactic acid is found but in sour milk both (+)-lactic acid and
(-)-lactic acid are present. Explain this observation.
ANS:
Short answer: Some type of stereoselectivity occurs
in muscles that does not occur in milk.
Longer Answer: The production of lactic acid in muscle
tissue is catalyzed by biological catalysts or enzymes. Enzymes are
stereospecific in the substrates (reactants) upon which they can act as well as
in the products they produce. Additionally, the substrates in such biological
reactions also are only one of the two enantiomers. The souring of milk is a
“purely chemical” process that is not stereoselective.
46.
Draw astructure for a singly substituted chiral chloroalkane
with the that contains four carbon atoms. Indicate the chirality center with an
asterisk (*).
ANS:
The chirality center is indicated by the asterisk (*),
MULTIPLE CHOICE
1. Which
of the following objects is not chiral?
|
a. |
baseball glove |
|
b. |
ballerina slipper |
|
c. |
corkscrew |
|
d. |
comb |
|
e. |
All are chiral. |
ANS: D
2. Which
of the following would be has the highest priority according to the sequence
rules?
|
a. |
—SH |
c. |
—CH3 |
|
b. |
—NH2 |
d. |
—OH |
ANS: A
3. Which
of the following arranges the groups in order of decreasing priority
according to the sequence rules?
|
a. |
CH3 > CH2CH3 > CH2OH > CO2H |
c. |
CH2OH > CO2H > CH2CH3 > CH3 |
|
b. |
CH3 > CH2CH3 > CO2H >CH2OH |
d. |
CO2H > CH2OH > CH2CH3 > CH3 |
ANS: D
4. In
which of the following groups can the carbon atom be a chiral center?
|
a. |
|
|
b. |
|
|
c. |
|
|
d. |
|
|
e. |
The carbon atoms cannot be a chiral
center in any of these groups. |
ANS: E
5. Which
of the following compounds will rotate the plane of polarized light?
|
a. |
|
c. |
|
|
b. |
|
d. |
|
ANS: C
6. For
which of the following generic substances is it not possible to isolate the
enantiomers? (R1, R2 and R3 represent
different groups.)
|
a. |
|
|
b. |
|
|
c. |
|
|
d. |
It is possible to isolate the
enantiomers of all of these. |
|
e. |
It is not possible to isolate the
enantiomers of any of these. |
ANS: A
7. In
muscles during strenuous exercise, under anaerobic conditions lactic acid
builds up due to the following reaction.
The carbon atom indicated by the asterisk is
|
a. |
chiral |
c. |
prochiral |
|
b. |
achiral |
d. |
both achiral and prochiral |
ANS: D
8. A
compound with [a]D = +35.4° reacts to form a single product.
The product of the reaction shows no optical activity. This could mean
that the product is:
|
a. |
a racemate. |
|
b. |
does not have any chiral centers. |
|
c. |
is a meso compound. |
|
d. |
Any of the above are possible
explanations. |
ANS: D
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