Mirror, Mirror, on the Wall

1
Mirror, Mirror, on the Wall
A Study in Chirality
2
Do You Know...

• what an isomer is?
• how many kinds of isomers there are? (Hint use
  your textbook index.)

• ? Isomers are different compounds that have the
  same molecular formula.
• ? There are conformational, constitutional
  (structural), and stereoisomers.

3
Conformational Isomers

• Parts of the molecule rotate freely around a
  single bond but do not change location on the
  molecule.
• These isomers will not have different physical or
  chemical properties, since they can change their
  shape easily.

4
Conformational Isomers

• All of these images are 1-propanol arranged in
  different conformations.
• The order of attachment is the same in all.

5
Constitutional Isomers

• Constitutional isomers have the same molecular
  formula, but the groups and/or atoms are attached
  to the molecule in a different order.
• Constitutional isomers may also have different
  kinds of bonds within the molecules.

6
Constitutional Isomers

• C3H7Cl can be either 1-chloropropane or
  2-chloropropane.

H H H
ClCCCH H
H H
H Cl H
HCCCH H H
H
7
Constitutional Isomers

• C3H6O can have two different structures.
• What are the names of these compounds?

H H
OCCCH H H H
H H \ CCCOH /
H H H
? The first compound is called propanal. The
second compound is 2-propen-1-ol.
8
Stereoisomers

• In stereoisomers the atoms and/or groups are
  attached to the molecule in the same order, but
  they have a different orientation in space.
• There are several different types of
  stereoisomers. We have already studied one type.

9
Cis and Trans Isomers

• Recall from Chapter 12 (Section 12.2) that
  alkenes can exist as cis and trans isomers.
• Cis and trans isomers are one type of
  stereoisomer.
• They have the same atoms and/or groups, but they
  are attached to different sides of the double
  bond.

10

• This structure is a cis isomer, with the groups
  both on the same side of the double bond in the
  molecule.

11

• And this is a trans isomer, with the groups on
  opposite sides of the double bond.

12
Can You Match These?
A

• Trans-2-pentene ___
• Trans-2-methyl-3-hexene ___
• Cis-2-butene ___
• Cis-2-pentene ___

D
C
B
A
B
C
D
13
Stereoisomers

• We will now begin to explore isomers based on the
  groups around specific carbon atoms within a
  molecule.

This chapter will be taught by YOU using Power
Point presentations!
14
Your Group Tasks

• You will work in groups of three students, with
  each member of the group contributing to the
  presentation.
• Each group will be assigned a different concept
  from within this chapter.

15
Your Group Tasks

• You will use your textbook and Internet resources
  to gather information on your assigned topic.
• Each group will make and photograph molecular
  models illustrating your topic. You may also use
  images from other sources with appropriate
  permission.

16
Your Group Tasks

• Each group will create and present a Power Point
  presentation that teaches about their assigned
  topic.
• Complete details for the project will be found on
  your handout.

17
Individual Responsibilities

• Each student is responsible for learning the
  vocabulary from the entire chapter.
• Each student is responsible for learning the
  material presented by their group and by the
  other groups.

18
Individual Responsibilities

• Each student is responsible for learning any
  material presented by the teacher.
• Each student will be individually assessed by
  written and manipulative tests.