Chemistry Reference
In-Depth Information
5.3
a.
H
b.
H
H
*
Br
C
C
H
3
Br
C
C
H
H
no stereogenic centers; achiral
chiral
5.4
Note that if the right structure is rotated 180
°
about the carbon-phenyl bond, the
methyl and phenyl groups can be superimposed on those of the left structure, but the
positions of the hydrogen and bromine will be interchanged.
C
C
H
3
C
CH
3
Br
Br
H
H
5.5
The planes of symmetry are (a) the three planes that pass through any pair of
eclipsed hydrogens and (b) the perpendicular bisector of the C-C bond. Ethane in
this conformation is achiral.
H
H
H
H
H
H
5.6
There are three planes of symmetry that pass through any pair of anti-hydrogens.
Ethane in this conformation is achiral.
H
H
H
H
H
H
5.7
cis
-1,2-Dichloroethene has a plane of symmetry that bisects the double bond. The
molecular plane is also a symmetry plane.
trans
-1,2-Dichloroethene is planar. That
plane is a symmetry plane. Both
cis
- and
trans
-1,2-dichloroethene are achiral.
Cl
Cl
Cl
H
H
H
H
Cl
