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Chapter 4 183
Copyright © 2017 Pearson Education, Inc.
103.
a.
The compounds do not have any asymmetric centers.
b. 1.
It is not chiral.
2.
It is chiral. Because of its unusual geometry, it is a chiral molecule, even though it does not have
any asymmetric centers, because it cannot be superimposed on its mirror image. This will be eas-
ier to understand if you build models.
C C C
H
H
H
H
mirror
CCC
H
H
H
H
C C C
H
CH
3
H
mirror
CCC
H
CH
3
H
images are superimposable
images are not superimposable
CH
3
CH
3
104.
The compound is not optically active because it has a point of symmetry.
A point of symmetry is a point, and if a line is drawn to this point from an atom or a group and then
extended an equal distance beyond the point, the line will touch an identical atom or group.
Cl
Cl
Br
Br
point of symmetry
•
105.
a.
Br
C
R
H
CH
3
HO
c.
H
Br
R
CH
2
CH
CH
3
CH
2
e.
S
R
Br
CH
3
H
CH
3
H Br
b.
R
C1
CH
3
CH
2
C1
H
d.
R
R
S
HC O
HO H
OH
OH
H
H
CH
2
OH
f.
R
Br
C1
H
CH
3
CH
3
H
S